Task 32 at the Unified State Examination in Chemistry (the former task C2 of the “new type”) contains a description of an experiment consisting of sequential chemical reactions and laboratory methods for separating reaction products ( thought experiment).
In my experience, this task is difficult for many students. To a large extent, this is due to the increasingly academic nature of teaching chemistry in schools and courses, when insufficient attention is paid to the study of the features of work in the laboratory and the actual conduct of laboratory experiments.
Therefore, I decided to systematize and summarize the material on the so-called. "laboratory" chemistry. This article discusses examples of task 32 in the Unified State Examination in Chemistry-2018 (former task C2), with a detailed analysis and analysis of the solution.
This assignment requires a good understanding of certain topics. general chemistry and chemistry of elements, namely: main , Chemical properties and getting, acids, and salts, and the relationship between different classes of inorganic substances; properties of simple substances - metals and non-metals; ; ; , , halogens.
- The solution obtained by the interaction of copper with concentrated nitric acid was evaporated and the precipitate was calcined. The gaseous products of the decomposition reaction are completely absorbed by water, and hydrogen is passed over the solid residue. Write the equations of the described reactions.
Analysis and decision.
"Keywords" - concentrated nitric acid and copper.
Copper is an inactive metal, it exhibits the properties of a reducing agent.
Keywords: " … The resulting product was sequentially treated with sulfur dioxide and barium hydroxide solution.". The sodium sulfate obtained in the previous step enters into an ion exchange reaction with barium hydroxide to precipitate barium sulfate (equation 4).
1) 2NaCl \u003d 2Na + Cl 2
2) 2Na + O 2 = Na 2 O 2
3) Na 2 O 2 + SO 2 = Na 2 SO 4
4) Na 2 SO 4 + Ba(OH) 2 = NaOH + BaSO 4
5.The decomposition products of ammonium chloride were successively passed through a heated tube containing copper (II) oxide, and then through a flask with phosphorus (V) oxide. Write the equations of the described reactions.
Analysis and decision.
Keywords: " Decomposition products of ammonium chloride... ". Ammonium chloride is a salt that decomposes when a solid salt is heated into gaseous ammonia and hydrogen chloride gas (equation 1)
Next, the products of reactions 2 and 3 are passed through a container with phosphorus (V) oxide. Analyzing the possibility of a leak chemical reaction between substances. The simple substance copper is chemically inactive and does not react with phosphorus. The simple substance nitrogen is also chemically inactive; it does not react with phosphorus (V) oxide. But with acidic phosphorus (V) oxide, water vapor perfectly reacts with the formation of ortho-phosphoric acid (equation 4).
1) NH 4 Cl \u003d NH 3 + HCl
2) CuO + 2HCl = CuCl 2 + H2O
3) 3CuO + 2NH 3 = 3Cu + N 2 + 3H2O
4) 3H 2 O + P 2 O 5 \u003d 2H 3 PO 4
6. To a water-insoluble salt white color, which occurs in nature in the form of a mineral widely used in construction and architecture, a solution of hydrochloric acid was added, as a result, the salt dissolved and gas was released, which, when passed through lime water, precipitated a white precipitate; the precipitate dissolved upon further passing of the gas. When the resulting solution is boiled, a precipitate forms. Write the equations of the described reactions.
Analysis and decision.
It is well known from a school chemistry course that a white salt insoluble in water, which occurs in nature in the form of a mineral widely used in construction and architecture, is calcium carbonate CaCO 3 . Insoluble salts dissolve under the action of stronger acids, in this case, hydrochloric acid (Equation 1).
Produced gas passed through lime water Ca(OH)2. Carbon dioxide is a typical acid oxide, which, when interacting with an alkali, forms a salt - calcium carbonate (equation 2). Further the precipitate dissolved upon further passing of the gas. Here is a very important property: medium salts of polybasic acids under the action of an excess of acid form more acidic salts . Calcium carbonate in excess of carbon dioxide forms a more acidic salt - calcium bicarbonate Ca (HCO 3) 2, which is highly soluble in water (equation 3).
The properties of acid salts are largely the sum of the properties of compounds forming acid salts. The properties of calcium bicarbonate are determined by the properties of its constituent compounds - carbonic acid H 2 CO 3 and calcium carbonate. It is easy to deduce that when boiled, bicarbonate will decompose into calcium carbonate (it is distributed at higher temperatures, about 1200 degrees Celsius), carbon dioxide and water (equation 4).
1) CaCO 3 + 2HCl = CaCl 2 + CO 2 + H 2 O
2) CO 2 + Ca (OH) 2 \u003d CaCO 3 + H 2 O
3) CaCO 3 + H 2 O + CO 2 \u003d Ca (HCO 3) 2
4) Ca (HCO 3) 2 \u003d CaCO 3 + H 2 O + CO 2
7. Substance obtained from anode during the electrolysis of sodium iodide solution with inert electrodes, reacted with hydrogen sulfide. The resulting solid was fused with aluminum and the product was dissolved in water. Write the equations of the described reactions.
Analysis and decision.
The electrolysis of a sodium iodide solution with inert electrodes is described by the equation:
1. 2NaI + 2H 2 O \u003d 2NaOH + H 2 + I 2
2. I 2 0 + H 2 S -2 \u003d 2HI - + S 0
In this case, solid sulfur was formed. Sulfur reacts with aluminum when fused to form aluminum sulfide. Most non-metals react with metals to form binary compounds:
3. 3S 0 + 2Al 0 \u003d Al 2 +3 S 3 -2
The reaction product of aluminum with sulfur - aluminum sulfide - when dissolved in water, irreversibly decomposes into aluminum hydroxide and hydrogen sulfide:
4. Al 2 S 3 + 12H 2 O \u003d 2Al (OH) 3 + 3H 2 S
Such reactions are also called reactions. Cases of irreversible hydrolysis are considered in detail in.
8 . The gas released during the interaction of hydrogen chloride with potassium permanganate reacts with iron. The reaction product was dissolved in water, and sodium sulfide was added thereto. The lighter insoluble matter formed was separated and reacted with hot concentrated nitric acid. Write the equations of the described reactions.
9. Chromium(III) sulfide was treated with water, which released gas and left an insoluble substance. A solution of caustic soda was added to this substance and gaseous chlorine was passed through, while the solution acquired a yellow color. The solution was acidified with sulfuric acid, as a result, the color changed to orange; the gas released during the treatment of sulfide with water was passed through the resulting solution, and the color of the solution changed to green. Write the equations of the described reactions.
Analysis and decision.
Keywords: " Chromium (III) sulfide was treated with water, while gas was released and an insoluble substance remained«. Chromium (III) sulfide decomposes under the action of water into hydroxide and hydrogen sulfide . The hydrolysis reactions of such compounds are discussed in detail in. (reaction 1)
1) Cr 2 S 3 + 6H 2 O \u003d 2Cr (OH) 3 + 3H 2 S
Key words: "... they added a solution of caustic soda and passed gaseous chlorine, while the solution acquired a yellow color." Under the action of chlorine in an alkaline environment, chromium +3 is oxidized to chromium +6 . Chromium +6 forms an acid oxide and hydroxide, in a solution of sodium hydroxide it forms a stable yellow salt - sodium chromate (reaction 2).
2) 2Cr +3 (OH) 3 + 3Cl 0 2 + 10NaOH = 2Na 2 Cr +6 O 4 + 6NaCl - + 8H 2 O
Next, the key words: The solution was acidified with sulfuric acid, as a result, the color changed to orange.«. Salts-chromates in an acidic medium turn into dichromates. Yellow sodium chromate in an acid medium turns into orange sodium dichromate (reaction 3). This is not OVR!
3) 2Na 2 CrO 4 + H 2 SO 4 = Na 2 Cr 2 O 7 + Na 2 SO 4 + H 2 O.
Further: “... the gas released during the treatment of sulfide with water was passed through the resulting solution, and the color of the solution changed to green.” Sodium dichromate is a strong oxidizing agent; when interacting with hydrogen sulfide, it is reduced to a trivalent chromium salt. Chromium (III) compounds are amphoteric; they form salts in an acidic environment. Salts of chromium (III) color the solution green (reaction 4).
4) Na 2 Cr +6 2 O 7 + 3H 2 S -2 + 4H 2 SO 4 = 3S 0 + Cr +3 2 (SO 4) 3 + Na 2 SO 4 + 7H 2 O
10. Obtaining a black and white image when photographing is based on the decomposition of an unknown metal salt under the action of light. When this metal is dissolved in dilute nitric acid, a colorless gas is released, which quickly changes its color to brown in air, and a salt is formed that interacts with sodium bromide to form a yellowish cheesy precipitate. The anion in the salt used in photography is an acid anion, which is formed simultaneously with sulfuric acid, when bromine water and sulfur dioxide react. Write the equations of the described reactions.
11. Sodium hydroxide solution was added dropwise to the solution obtained by reacting aluminum with dilute sulfuric acid until a precipitate formed. The white precipitate formed was filtered off and dried. The resulting substance was fused with sodium carbonate. Write the equations of the described reactions.
Analysis and decision.
Dilute sulfuric acid, when interacting with metals, behaves like ordinary mineral acid. Metals that are in the series of electrochemical activity to the left of hydrogen, when interacting with mineral acids, displace hydrogen:
1.2Al 0 + 3H + 2 SO 4 \u003d Al +3 2 (SO 4) 3 + 3H 0 2
Further, aluminum sulfate interacts with sodium hydroxide. The condition states that sodium hydroxide was added dropwise. This means that sodium hydroxide was in short supply, and aluminum sulfate was in significant excess. Under these conditions, a precipitate of aluminum hydroxide is formed:
2. Al 2 (SO 4) 3 + 6NaOH \u003d 2Al (OH) 3 + 3Na 2 SO 4
The white precipitate is aluminum hydroxide, insoluble in water. P On calcination, insoluble hydroxides decompose into water and the corresponding oxide :
3. 2Al(OH) 3 \u003d Al 2 O 3 + 3H 2 O
The resulting substance, aluminum oxide, was fused with sodium carbonate. In the melt, less volatile oxides displace more volatile ones from salts.. A carbonate is a salt that corresponds to a volatile oxide, carbon dioxide. Accordingly, when alkali metal carbonates are fused with solid oxides (acidic and amphoteric), a salt corresponding to this oxide and carbon dioxide are formed:
4. Al 2 O 3 + Na 2 CO 3 \u003d 2NaAlO 2 + CO 2
12. Through a solution of copper chloride (II) using graphite electrodes passed a constant electricity. The electrolysis product released at the cathode was dissolved in concentrated nitric acid. The resulting gas was collected and passed through a sodium hydroxide solution. The gaseous product of electrolysis released at the anode was passed through a hot solution of sodium hydroxide. Write the equations of the described reactions.
13. A simple substance obtained by heating a mixture of calcium phosphate with coke and silicon oxide dissolves in a solution of caustic potash. The escaping gaseous substance was burned, the combustion products were collected and cooled, and silver nitrate was added to the resulting solution. Write the equations of the described reactions.
14. The foul-smelling liquid formed by the interaction of hydrogen bromide with potassium permanganate was separated and heated with iron filings. The reaction product was dissolved in water, and a cesium hydroxide solution was added thereto. The precipitate formed was filtered off and calcined. Write the equations of the described reactions.
15. Electric discharges were passed over the surface of the caustic soda solution, while the air turned brown, and the color disappeared after a while. The resulting solution was carefully evaporated and found that the solid residue is a mixture of two salts. Keeping a mixture of salts in air leads to the formation of one substance. Write the equations of the described reactions.
16. Calcium is dissolved in water. When passing through the resulting solution of sulfur dioxide, a white precipitate is formed, which dissolves when passing an excess of gas. The addition of alkali to the resulting solution leads to the formation of a white precipitate. Write the equations of the described reactions.
17. When a simple yellow substance is burned in air, a gas with a pungent odor is formed. This gas is also released when a certain mineral containing iron is burned in air. Under the action of dilute sulfuric acid on a substance consisting of the same elements as the mineral, but in a different ratio, a gas is released with a characteristic smell of rotten eggs. When the released gases interact with each other, the initial simple substance is formed. Write the equations of the described reactions.
18. The gaseous product of the interaction of dry common salt with concentrated sulfuric acid was reacted with a solution of potassium permanganate. The evolved gas was passed through a solution of sodium sulfide. The resulting yellow precipitate is dissolved in a concentrated solution of sodium hydroxide. Write the equations of the described reactions.
19. The gas formed when hydrogen chloride is passed through a hot potassium chromate solution reacts with iron. The reaction product was dissolved in water, and sodium sulfide was added thereto. The lighter insoluble matter formed was separated and reacted with concentrated sulfuric acid by heating. Write the equations of the described reactions.
20. Two salts contain the same cation. The thermal decay of the first of them resembles a volcanic eruption, while a low-active colorless gas is released, which is part of the atmosphere. When the second salt interacts with a solution of silver nitrate, a white curdled precipitate is formed, and when it is heated with an alkali solution, a colorless poisonous gas with a pungent odor is released; this gas can also be obtained by reacting magnesium nitride with water. Write the equations of the described reactions.
21. An excess of sodium hydroxide solution was added to the aluminum sulfate solution. Hydrochloric acid was added in small portions to the resulting solution, and the formation of a bulky white precipitate was observed, which dissolved with further addition of acid. A solution of sodium carbonate was added to the resulting solution. Write the equations of the described reactions.
22. Electric discharges were passed over the surface of the caustic soda solution poured into the flask, while the air in the flask turned brown, which disappeared after a while. The resulting solution was carefully evaporated and found that the solid residue is a mixture of two salts. When this mixture is heated, gas is released and only one substance remains. Write the equations of the described reactions.
23. Zinc oxide was dissolved in hydrochloric acid solution and the solution was neutralized by adding sodium hydroxide. The separated white gelatinous substance was separated and treated with an excess of alkali solution, while the precipitate completely dissolved. Neutralization of the resulting solution with an acid, such as nitric acid, leads to the re-formation of a gelatinous precipitate. Write the equations of the described reactions.
24. The substance obtained at the cathode during the electrolysis of a copper (II) chloride melt reacts with sulfur. The resulting product was treated with concentrated nitric acid and the evolved gas was passed through a barium hydroxide solution. Write the equations of the described reactions.
25. A mixture of calcium orthophosphate, coke and sand was heated in an electric furnace. One of the products of this reaction can ignite spontaneously in air. The solid combustion product of this substance was dissolved in water when heated, and gaseous ammonia was passed through the resulting solution. Write the equations of the described reactions.
26. The substance obtained at the cathode during the electrolysis of a solution of iron (II) chloride was fused with sulfur, and the product of this reaction was calcined. The resulting gas was passed through a solution of barium hydroxide. Write the equations of the described reactions.
27. A copper wire was introduced into heated concentrated sulfuric acid, and the escaping gas was passed through an excess of sodium hydroxide solution. The solution was carefully evaporated, the solid residue was dissolved in water and heated with powdered sulfur. The unreacted sulfur was separated by filtration, and sulfuric acid was added to the solution, while a precipitate was observed and a gas with a pungent odor was evolved. Write the equations of the described reactions.
28. After briefly heating an unknown orange powder, a spontaneous reaction begins, which is accompanied by a change in color to green, the release of gas and sparks. The solid residue was mixed with caustic potash and heated, the resulting substance was added to a dilute solution of hydrochloric acid, and a precipitate formed. Green colour, which dissolves in excess acid. Write the equations of the described reactions.
29. Two salts color the flame in purple. One of them is colorless, and when it is slightly heated with concentrated sulfuric acid, a liquid is distilled, in which copper dissolves; the last transformation is accompanied by the evolution of brown gas. When the second salt of the sulfuric acid solution is added to the solution, the yellow color of the solution changes to orange, and when the resulting solution is neutralized with alkali, the original color is restored. Write the equations of the described reactions.
30. An iron (III) chloride solution was subjected to electrolysis with graphite electrodes. The brown precipitate formed as a by-product of the electrolysis was filtered off and calcined. The substance formed on the cathode was dissolved in concentrated nitric acid by heating. The product separated at the anode was passed through a cold solution of potassium hydroxide. Write the equations of the described reactions.
31. The gas released during the interaction of hydrogen chloride with Berthollet salt was reacted with aluminum. The reaction product was dissolved in water and sodium hydroxide was added until the precipitation ceased, which was separated and calcined. Write the equations of the described reactions.
32. The unknown salt is colorless and turns the flame yellow. When this salt is slightly heated with concentrated sulfuric acid, a liquid is distilled off, in which copper dissolves; the last transformation is accompanied by the evolution of brown gas and the formation of a copper salt. During the thermal decomposition of both salts, one of the decomposition products is oxygen. Write the equations of the described reactions.
33. The substance obtained at the anode during the electrolysis of a melt of sodium iodide with inert electrodes was isolated and introduced into interaction with hydrogen sulfide. The gaseous product of the last reaction was dissolved in water, and ferric chloride was added to the resulting solution. The precipitate formed was filtered off and treated with hot sodium hydroxide solution. Write the equations of the described reactions.
34. Gases that are released when coal is heated in concentrated nitric and sulfuric acids are mixed with each other. The reaction products were passed through milk of lime. Write the equations of the described reactions.
35. A mixture of iron powder and a solid product obtained by the interaction of sulfur dioxide and hydrogen sulfide was heated without air. The resulting product was calcined in air. The resulting solid reacts with aluminum, releasing a large amount of heat. Write the equations of the described reactions.
36. A black substance was obtained by calcining the precipitate, which is formed by the interaction of solutions of sodium hydroxide and copper (II) sulfate. When this substance is heated with coal, a red metal is obtained, which dissolves in concentrated sulfuric acid. Write the equations of the described reactions.
37. A simple substance, a mixture of which is used in matches with Berthollet salt and ignites when rubbed, was burned in an excess of oxygen. The white solid resulting from combustion was dissolved in an excess of sodium hydroxide solution. The resulting salt with a solution of silver nitrate forms a bright yellow precipitate. Write the equations of the described reactions.
38. Zinc was dissolved in very dilute nitric acid, and an excess of alkali was added to the resulting solution, obtaining a clear solution. Write the equations of the described reactions.
39. The solution obtained by passing sulfur dioxide through bromine water was neutralized with barium hydroxide. The precipitate that formed was separated, mixed with coke, and calcined. When the calcination product is treated with hydrochloric acid, a gas with the smell of rotten eggs is released. Write the equations of the described reactions.
40. The substance formed when zinc powder was added to a solution of ferric chloride was separated by filtration and dissolved in hot dilute nitric acid. The solution was evaporated, the solid residue was calcined, and the evolved gases were passed through a solution of sodium hydroxide. Write the equations of the described reactions.
41. The gas released during heating of a solution of hydrogen chloride with manganese (IV) oxide was introduced into interaction with aluminum. The reaction product was dissolved in water and first an excess of sodium hydroxide solution was added, and then hydrochloric acid (excess). Write the equations of the described reactions.
42. A mixture of two colorless, colorless and odorless gases A and B was passed by heating over a catalyst containing iron, and the resulting gas B neutralized the hydrobromic acid solution. The solution was evaporated and the residue heated with caustic potash, as a result, a colorless gas B with a pungent odor was released. When gas B is burned in air, water and gas A are formed. Write the equations for the described reactions.
43. Sulfur dioxide was passed through a solution of hydrogen peroxide. Water was evaporated from the resulting solution, and magnesium shavings were added to the residue. The evolved gas was passed through a solution of copper sulphate. The black precipitate that formed was separated and fired. Write the equations of the described reactions.
44. A solution of hydrochloric acid was poured into a water-insoluble white salt, which occurs in nature in the form of a mineral widely used in construction and architecture, as a result, the salt dissolved and a gas was released, which, when passed through lime water, precipitated a white precipitate, which dissolved with further passing gas. When an excess of lime water is added to the resulting solution, a precipitate forms. Write the equations of the described reactions.
45. When a certain mineral A, consisting of two elements, is burned, a gas is formed that has a characteristic pungent odor and decolorizes bromine water to form two strong acids in solution. When substance B, which consists of the same elements as mineral A, but in a different ratio, interacts with concentrated hydrochloric acid, a poisonous gas with the smell of rotten eggs is released. When the released gases interact with each other, a simple yellow substance and water are formed. Write the equations of the described reactions.
46. The substance released at the cathode during the electrolysis of a melt of sodium chloride was burned in oxygen. The resulting product was placed in a gasometer filled with carbon dioxide. The resulting substance was added to a solution of ammonium chloride and the solution was heated. Write the equations of the described reactions.
47. The nitric acid was neutralized with baking soda, the neutral solution was carefully evaporated, and the residue was calcined. The resulting substance was introduced into a solution of potassium permanganate acidified with sulfuric acid, and the solution became colorless. The nitrogen-containing reaction product was placed in a sodium hydroxide solution and zinc dust was added, and a gas with a sharp characteristic odor was released. Write the equations of the described reactions.
48. When salt solution A reacted with alkali, a gelatinous, water-insoluble blue substance was obtained, which was dissolved in a colorless liquid B to form a solution of blue color. The solid product remaining after careful evaporation of the solution was calcined; in this case, two gases were released, one of which is brown, and the second is part of the atmospheric air, and a black solid remains, which dissolves in liquid B with the formation of substance A. Write the equations of the described reactions.
49. White phosphorus dissolves in a solution of caustic potash with the release of a gas with a garlic odor, which ignites spontaneously in air. The solid product of the combustion reaction reacted with caustic soda in such a ratio that the resulting white substance contains one hydrogen atom; when the latter substance is calcined, sodium pyrophosphate is formed. Write the equations of the described reactions.
50. A solution of ferric chloride was treated with a solution of sodium hydroxide, the precipitate that formed was separated and heated. The solid reaction product was mixed with soda ash and calcined. Both sodium nitrate and sodium hydroxide were added to the remaining substance and heated at a high temperature for a long time. Write the equations of the described reactions.
The gas released during the interaction of hydrogen chloride with potassium permanganate was passed through a solution of sodium tetrahydroxoaluminate. The precipitate formed was filtered off, calcined, and the solid residue was treated hydrochloric acid. Write the equations of the described reactions.
The nitric-hydrogen mixture was heated to a temperature of 500°C and under high pressure passed over an iron catalyst. The reaction products were passed through a solution of nitric acid until it was neutralized. The resulting solution was carefully evaporated, the solid residue was calcined, and the resulting gas was passed over copper while heating, resulting in a black solid. Write the equations of the described reactions.
Trivalent chromium hydroxide was treated with hydrochloric acid. Potash was added to the resulting solution, the precipitate was separated and added to a concentrated solution of potassium hydroxide, as a result, the precipitate dissolved. After adding an excess of hydrochloric acid, a green solution was obtained. Write the equations of the described reactions.
The substance obtained at the anode during the electrolysis of a sodium iodide solution with inert electrodes was introduced into a reaction with potassium. The reaction product was heated with concentrated sulfuric acid and the evolved gas was passed through a hot solution of potassium chromate. Write the equations of the described reactions.
Ferrous oxide was heated with dilute nitric acid. The solution was carefully evaporated, the solid residue was dissolved in water, iron powder was added to the resulting solution, and after a while it was filtered. A solution of caustic potassium was added to the filtrate, the precipitate that formed was separated and left in air, while the color of the substance changed. Write the equations of the described reactions.
One of the substances formed when silicon oxide is fused with magnesium dissolves in alkali. The released gas was reacted with sulfur, and the product of their interaction was treated with chlorine. Write the equations of the described reactions.
The solid substance formed by the interaction of sulfur dioxide and hydrogen sulfide reacts with aluminum when heated. The reaction product was dissolved in dilute sulfuric acid, and potash was added to the resulting solution. Write the equations of the described reactions.
An unknown metal was burned in oxygen. The reaction product, interacting with carbon dioxide, forms two substances: a solid, which interacts with a solution of hydrochloric acid with the release of carbon dioxide, and a gaseous simple substance that supports combustion. Write the equations of the described reactions.
The product of the interaction of nitrogen and lithium was treated with water. The gas released as a result of the reaction was mixed with an excess of oxygen and, when heated, was passed over a platinum catalyst; the resulting gas mixture had a brown color. Write the equations of the described reactions.
Copper shavings were dissolved in dilute nitric acid and the solution was neutralized with caustic potash. The released blue substance was separated, calcined (the color of the substance changed to black), mixed with coke and re-calcined. Write the equations of the described reactions.
Phosphorus was burned in an excess of chlorine, the resulting solid was mixed with phosphorus and heated. The reaction product was treated with water, and a colorless gas with a pungent odor was released. The solution was added to a solution of potassium permanganate acidified with sulfuric acid, which became colorless as a result of the reaction. Write the equations of the described reactions.
Ferric chloride was treated with concentrated nitric acid on heating and the solution was carefully evaporated. The solid product was dissolved in water, potash was added to the resulting solution, and the precipitate that formed was separated and calcined. Gaseous hydrogen was passed over the resulting substance during heating. Write the equations of the described reactions.
An unknown salt, when interacting with a solution of silver nitrate, forms a white precipitate and colors the burner flame yellow. When concentrated sulfuric acid reacts with this salt, a poisonous gas is formed, which is highly soluble in water. Iron dissolves in the resulting solution, and a very light colorless gas is released, which is used to obtain metals, such as copper, from their oxides. Write the equations of the described reactions.
Magnesium silicide was treated with a solution of hydrochloric acid, and the escaping gas was burned. The solid reaction product was mixed with soda ash, the mixture was heated to melting and held for some time. After cooling, the reaction product (commonly used under the name "water glass") was dissolved in water and treated with a solution of sulfuric acid. Write the equations of the described reactions.
A gaseous mixture of ammonia and a large excess of air was passed on heating over platinum, and after a while the reaction products were absorbed by a solution of sodium hydroxide. After evaporation of the solution, a single product was obtained. Write the equations of the described reactions.
Soda ash was added to a solution of ferric chloride, and the precipitate that formed was separated and calcined. Carbon monoxide was passed over the resulting substance during heating, and the solid product of the last reaction was introduced into interaction with bromine. Write the equations of the described reactions.
The product of the interaction of sulfur with aluminum (the reaction proceeds when heated) was dissolved in cold dilute sulfuric acid, and potassium carbonate was added to the solution. The resulting precipitate was separated, mixed with caustic soda and heated. Write the equations of the described reactions.
Silicon (IV) chloride was heated in a mixture with hydrogen. The reaction product was mixed with magnesium powder, heated and treated with water; one of the formed substances ignites spontaneously in air. Write the equations of the described reactions.
A brown gas was passed through an excess of caustic potash solution in the presence of a large excess of air. Magnesium shavings were added to the resulting solution and heated; the liberated gas neutralized nitric acid. The resulting solution was carefully evaporated, the solid reaction product was calcined. Write the equations of the described reactions.
Iron scale was dissolved in concentrated nitric acid by heating. The solution was carefully evaporated and the reaction product was dissolved in water. Iron powder was added to the resulting solution, after a while the solution was filtered and the filtrate was treated with a solution of caustic potash, as a result, a light green precipitate formed, which quickly darkened in air. Write the equations of the described reactions.
A solution of aluminum chloride was added to a solution of soda ash, the released substance was separated and added to a solution of caustic soda. A solution of hydrochloric acid was added dropwise to the resulting solution until the formation of a precipitate ceased, which was separated and calcined. Write the equations of the described reactions.
Copper shavings were added to a solution of mercury (II) nitrate. After completion of the reaction, the solution was filtered and the filtrate was added dropwise to a solution containing sodium hydroxide and ammonium hydroxide. At the same time, a short-term formation of a precipitate was observed, which dissolved with the formation of a bright blue solution. When an excess of sulfuric acid solution was added to the resulting solution, a color change occurred. Write the equations of the described reactions.
The product of the interaction of magnesium phosphide with water was burned and the reaction products were absorbed by water. The resulting substance is used in industry to obtain double superphosphate from phosphorite. Write the equations of the described reactions.
The salt obtained by reacting zinc oxide with sulfuric acid was calcined at 800°C. The solid reaction product was treated with a concentrated alkali solution and carbon dioxide was passed through the resulting solution. Write the reaction equations for the described transformations.
Iron powder was added to the ferric chloride solution, and after a while the solution was filtered. Sodium hydroxide was added to the filtrate, the separated precipitate was separated and treated with hydrogen peroxide. To the resulting substance was added an excess of a solution of caustic potassium and bromine; as a result of the reaction, the color of bromine disappeared. Write the equations of the described reactions.
Copper(I) oxide was treated with concentrated nitric acid, the solution was carefully evaporated, and the solid residue was calcined. The gaseous reaction products were passed through a large amount of water and magnesium shavings were added to the resulting solution, as a result, a gas used in medicine was released. Write the equations of the described reactions.
Sulfur dioxide was passed through a solution of hydrogen peroxide. The solution was evaporated and copper shavings were added to the remaining liquid. The evolved gas was mixed with the gas formed by the interaction of iron (II) sulfide with a solution of hydrobromic acid. Write the equations of the described reactions.
When adding dilute hydrochloric acid to a yellow salt solution, which turns the flame purple, the color changes to orange-red. After neutralizing the solution with concentrated alkali, the color of the solution returned to its original color. When barium chloride is added to the resulting solution, a yellow precipitate forms. The precipitate was filtered off and silver nitrate solution was added to the filtrate. Write the equations of the described reactions.
Magnesium silicide was treated with a solution of hydrochloric acid, the reaction product was burned, the resulting solid was mixed with soda ash and heated to melt. After cooling the melt, it was treated with water and nitric acid was added to the resulting solution. Write the equations of the described reactions.
The insoluble substance formed when caustic soda was added to a solution of ferric chloride was separated and dissolved in dilute sulfuric acid. Zinc dust was added to the resulting solution, the precipitate was filtered off and dissolved in concentrated hydrochloric acid. Write the equations of the described reactions.
Aluminum nitrate was calcined, the reaction product was mixed with soda ash and heated to melt. The resulting substance was dissolved in nitric acid and the resulting solution was neutralized with an ammonia solution, while the isolation of a bulky gelatinous precipitate was observed. Write the equations of the described reactions.
Magnesium nitride was treated with excess water. When passing the evolved gas both through bromine water or through a neutral solution of potassium permanganate, and when it is burned, the same gaseous product is formed. Write the equations of the described reactions.
Chlorine water has the smell of chlorine. When alkalized, the smell disappears, and when hydrochloric acid is added, it becomes stronger than it was before. Write the equations of the described reactions.
The solid substance formed when malachite is heated was heated in a hydrogen atmosphere. The reaction product was treated with concentrated sulfuric acid and, after separation from the sulfuric acid, was added to a sodium chloride solution containing copper filings, and a precipitate formed as a result. Write the equations of the described reactions.
Phosphine was passed through a hot solution of concentrated nitric acid. The solution was neutralized with quicklime, the precipitate that formed was separated, mixed with coke and silica, and calcined. The reaction product, which glows in air, was heated in a sodium hydroxide solution. Write the equations of the described reactions.
Iron powder was dissolved in a large amount of dilute sulfuric acid, and air was passed through the resulting solution, and then a gas with the smell of rotten eggs. The insoluble salt formed was separated and dissolved in a hot solution of concentrated nitric acid. Write the equations of the described reactions.
Colorless gases are released when concentrated sulfuric acid is kept with both sodium chloride and sodium iodide. When these gases are passed through an aqueous solution of ammonia, salts are formed. Write the equations of the described reactions.
Magnesium powder was mixed with silicon and heated. The reaction product was processed cold water and the escaping gas was passed through hot water. The resulting precipitate was separated, mixed with caustic soda and heated to melt. Write the equations of the described reactions.
One of the products of the interaction of ammonia with bromine, a gas that is part of the atmosphere, was mixed with hydrogen and heated in the presence of platinum. The resulting mixture of gases was passed through a solution of hydrochloric acid, and potassium nitrite was added to the resulting solution with slight heating. Write the equations of the described reactions.
The salt obtained by dissolving copper in dilute nitric acid was subjected to electrolysis using graphite electrodes. The substance released at the anode was introduced into interaction with sodium, and the resulting reaction product was placed in a vessel with carbon dioxide. Write the equations of the described reactions.
Unknown substance A dissolves in concentrated hydrochloric acid, the dissolution process is accompanied by the release of gas with the smell of rotten eggs; after neutralization of the solution with alkali, a volumetric precipitate of white (light green) color is formed. When substance A is fired, two oxides are formed. One of them is a gas that has a characteristic pungent odor and decolorizes bromine water with the formation of two strong acids in solution. Write the equations of the described reactions.
Magnesium was heated in a vessel filled with gaseous ammonia. The resulting substance was dissolved in a concentrated solution of hydrobromic acid, the solution was evaporated and the residue was heated until an odor appeared, after which an alkali solution was added. Write the equations of the described reactions.
Soda ash was added to a solution of trivalent chromium sulfate. The precipitate formed was separated, transferred to a sodium hydroxide solution, bromine was added, and heated. After neutralization of the reaction products with sulfuric acid, the solution acquires an orange color, which disappears after passing sulfur dioxide through the solution. Write the equations of the described reactions.
Quicklime was calcined with an excess of coke. The reaction product after treatment with water is used to absorb sulfur dioxide and carbon dioxide. Write the equations of the described reactions.
Ferrous sulfide was treated with a solution of hydrochloric acid, the escaping gas was collected and burned in the air. The reaction products were passed through an excess of potassium hydroxide solution, after which a solution of potassium permanganate was added to the resulting solution. Write the equations of the described reactions.
The solid product of the thermal decomposition of malachite was dissolved by heating in concentrated nitric acid. The solution was carefully evaporated and the solid residue was calcined to give a black substance, which was heated in excess ammonia (gas). Write the equations of the described reactions.
Red phosphorus was burned in an atmosphere of chlorine. The reaction product was treated with excess water and powdered zinc was added to the solution. The evolved gas was passed over heated ferrous oxide. Write the reaction equations for the described transformations.
The silvery-gray metal, which is attracted by a magnet, was brought into hot concentrated sulfuric acid and heated. The solution was cooled and caustic soda was added until the formation of an amorphous brown precipitate ceased. The precipitate was separated, calcined and dissolved in concentrated hydrochloric acid on heating. Write the equations of the described reactions.
Magnesium shavings were heated in a nitrogen atmosphere, and the reaction product was successively treated with boiling water, solutions of sulfuric acid, and barium nitrate. Write the equations of the described reactions.
During the thermal decomposition of salt A in the presence of manganese dioxide, a binary salt B and a gas that supports combustion and is part of the air were formed; when this salt is heated without a catalyst, salt B and a salt of a higher oxygen-containing acid are formed. When salt A reacts with hydrochloric acid, a yellow-green poisonous gas (a simple substance) is released and salt B is formed. Salt B colors the flame purple; when it interacts with a solution of silver nitrate, a white precipitate precipitates. Write the equations of the described reactions.
The precipitate obtained by adding caustic soda to the aluminum sulfate solution was separated, calcined, mixed with soda ash and heated to melt. After treatment of the residue with sulfuric acid, the initial aluminum salt was obtained. Write the equations of the described reactions.
The substance formed during the fusion of magnesium with silicon was treated with water, as a result a precipitate formed and a colorless gas was released. The precipitate was dissolved in hydrochloric acid, and the gas was passed through a solution of potassium permanganate, and two water-insoluble binary substances were formed. Write the equations of the described reactions.
The substance obtained by heating iron scale in a hydrogen atmosphere was introduced into hot concentrated sulfuric acid and heated. The resulting solution was evaporated, the residue was dissolved in water and treated with a barium chloride solution. The solution was filtered and a copper plate was added to the filtrate, which dissolved after a while. Write the equations of the described reactions.
Quicklime was "quenched" with water. A gas was passed into the resulting solution, which is released during the calcination of sodium bicarbonate, while the formation and subsequent dissolution of the precipitate were observed. Write the equations of the described reactions.
A mixture of nitrogen and hydrogen was successively passed over heated platinum and through a solution of sulfuric acid. Barium chloride was added to the solution, and after separating the precipitated precipitate, milk of lime was added and heated. Write the equations of the described reactions.
Give examples of interaction:
two acids
two bases
two acid salts
two acid oxides
Write the equations of the described reactions.
A solution of medium salt, formed by passing sulfur dioxide through an alkali solution, was left in the air for a long time. The solid formed after evaporation of the solution was mixed with coke and heated to a high temperature. When hydrochloric acid is added to the solid product of the reaction, a gas with the smell of rotten eggs is released. Write the equations of the described reactions.
A solution of dilute sulfuric acid was added to a black powdery substance and heated. A solution of caustic soda was added to the resulting blue solution until the precipitation ceased. The precipitate was filtered off and heated. The reaction product was heated in an atmosphere of hydrogen, resulting in a red substance. Write the equations of the described reactions.
Red phosphorus was burned in an atmosphere of chlorine, and a small amount (several drops) of water was added to the reaction product. The liberated substance was dissolved in an excess of water, iron powder was added to the resulting solution, and the gaseous reaction product was passed over a heated copper plate oxidized to bivalent copper oxide. Write the reaction equations for the described transformations.
An iron (III) chloride solution was subjected to electrolysis with graphite electrodes. The brown precipitate formed during electrolysis was filtered off and dissolved in a sodium hydroxide solution, after which an amount of sulfuric acid was added that was necessary to form a clear solution. The product separated at the anode was passed through a hot potassium hydroxide solution. Write the equations of the described reactions.
Aluminum chloride was added to a solution of crystalline soda, the precipitate was separated and treated with a solution of caustic soda. The resulting solution was neutralized with nitric acid, the precipitate separated and calcined. Write the equations of the described reactions.
Ammonia was mixed with a large excess of air, heated in the presence of platinum, and after a while absorbed in water. Copper shavings added to the resulting solution dissolve with the release of brown gas. Write the equations of the described reactions.
When an acid solution A is added to manganese dioxide, a poisonous yellow-green gas is released. By passing the released gas through a hot solution of caustic potash, a substance is obtained that is used in the manufacture of matches and some other incendiary compositions. During the thermal decomposition of the latter in the presence of manganese dioxide, a salt is formed, from which, when interacting with concentrated sulfuric acid, it is possible to obtain the initial acid A, and a colorless gas that is included in the composition of atmospheric air. Write the equations of the described reactions.
The product of the interaction of silicon with chlorine is easily hydrolyzed. When a solid hydrolysis product is fused with both caustic and soda ash, liquid glass is formed. Write the equations of the described reactions.
To the solution obtained by dissolving iron in hot concentrated hydrochloric acid, sodium hydroxide was added. The precipitate formed was separated, left in air for a long time, and then dissolved in dilute hydrochloric acid. Write the equations of the described reactions.
When heated, an orange substance decomposes; decomposition products include a colorless gas and a green solid. The released gas reacts with lithium even with slight heating. The product of the latter reaction interacts with water, and a gas with a pungent odor is released, which can restore metals, such as copper, from their oxides. Write the equations of the described reactions.
The rotten-egg-smelling gas was passed through concentrated sulfuric acid at room temperature. The resulting precipitate was separated and treated with hot concentrated nitric acid; the evolved gas was dissolved in a large amount of water, and a piece of copper was added to the resulting solution. Write the reaction equations for the described transformations.
The salt obtained by dissolving iron in hot concentrated sulfuric acid was treated with an excess of sodium hydroxide solution. The brown precipitate formed was filtered off and dried. The resulting substance was fused with iron. Write the equations of the described reactions.
Zinc metal was added to concentrated sulfuric acid. The resulting salt was isolated, dissolved in water, and barium nitrate was added to the solution. After separation of the precipitate, magnesium shavings were added to the solution, the solution was filtered, the filtrate was evaporated and calcined. Write the equations of the described reactions.
An unknown red substance was heated in chlorine and the reaction product was dissolved in water. Alkali was added to the resulting solution, the resulting blue precipitate was filtered off and calcined. When the calcination product, which is black in color, was heated with coke, a red starting material was obtained. Write the equations of the described reactions.
Iodine was heated with an excess of phosphorus and the reaction product was treated with a small amount of water. The gaseous reaction product was completely neutralized with sodium hydroxide solution and silver nitrate was added to the resulting solution. Write the equations of the described reactions.
Iron burned in chlorine. The reaction product was dissolved in water, and iron filings were added to the solution. After some time, the solution was filtered and sodium sulfide was added to the filtrate. The precipitate that formed was separated and treated with 20% sulfuric acid to give an almost colorless solution. Write the equations of the described reactions.
The gas released when solid salt is heated with concentrated sulfuric acid was passed through a solution of potassium permanganate. The gaseous reaction product was taken up in cold sodium hydroxide solution. After adding hydroiodic acid to the resulting solution, a pungent odor appears and the solution acquires a dark color. Write the equations of the described reactions.
A gas was passed through the solution obtained by slaking lime, which is formed when quicklime is obtained from limestone; the result is a white precipitate. Under the action of acetic acid on the resulting precipitate, the same gas is released that is formed during the calcination of calcium carbonate. Write the equations of the described reactions.
A red substance, which is used in the manufacture of matches, was burned in excess air and the reaction product was dissolved in a large amount of water when heated. After neutralizing the resulting solution with baking soda, silver nitrate was added to it. Write the equations of the described reactions.
A gas was passed through a solution of sodium bromide, which is released during the interaction of hydrochloric acid with potassium permanganate. After completion of the reaction, the solution was evaporated, the residue was dissolved in water and subjected to electrolysis with graphite electrodes. The gaseous products of the reaction were mixed with each other and illuminated, and the result was an explosion. Write the equations of the described reactions.
The gas formed during the combustion of coke was in contact with hot coal for a long time. The reaction product was successively passed through a layer of heated iron ore and quicklime. Write the equations of the described reactions.
Copper shavings were added to the heated concentrated sulfuric acid, and the released gas was passed through a solution of caustic soda (excess). The reaction product was isolated, dissolved in water, and heated with sulfur, which dissolved as a result of the reaction. Dilute sulfuric acid was added to the resulting solution. Write the equations of the described reactions.
Hydrochloric acid was added to solutions of substances L and B, which color the flame yellow, hydrochloric acid: When a solution of substance A reacts with hydrochloric acid, a colorless gas with an unpleasant odor is released, which forms a black precipitate when passed through a solution of lead (II) nitrate. When a solution of substance B is heated with hydrochloric acid, the color of the solution changes from yellow to green and a yellow-green poisonous gas with a characteristic pungent odor is released. When barium nitrate is added to a solution of substance B, a yellow precipitate forms. Write the equations of the described reactions.
A solution of hydrochloric acid was carefully added to the pyrolusite, and the escaping gas was passed into a beaker half-filled with a cold solution of caustic potash. After the reaction was completed, the glass was covered with cardboard and left, while the glass was illuminated by the sun's rays; after a while, a smoldering splinter was brought into the glass, which flared up brightly. Write the equations of the described reactions.
The precipitate obtained by the interaction of an aluminum salt solution and alkali was calcined. The reaction product was dissolved in a concentrated hot alkali solution. Carbon dioxide was passed through the resulting solution, resulting in a precipitate. Write the equations of the described transformations.
The black powder, which was formed during prolonged heating of the red metal in excess air, was dissolved in 10% sulfuric acid and a blue solution was obtained. Alkali was added to the solution, and the precipitate that formed was separated and dissolved in an excess of ammonia solution. Write the equations of the described reactions.
Phosphorus was added to the solid that forms when phosphorus is burned in excess chlorine, and the mixture is heated. The reaction product was treated with a small amount hot water and a solution of potassium permanganate acidified with sulfuric acid was added to the resulting solution. Write the equations of the described reactions.
Carbon dioxide was passed through barite water. Barium hydroxide was added to the resulting solution, the reaction product was separated and dissolved in phosphoric acid. Write the equations of the described reactions.
Zinc nitrate was calcined, the reaction product was treated with sodium hydroxide solution when heated. Carbon dioxide was passed through the resulting solution until the precipitation ceased, after which it was treated with an excess of concentrated ammonia, and the precipitate dissolved. Write the equations of the described reactions.
Two vessels contain solutions of unknown substances. When the first substance of barium chloride is added to the solution, a white precipitate forms, insoluble in water and acids. A white precipitate also occurs when a silver nitrate solution is added to a sample taken from the second vessel. When a sample of the first solution with sodium hydroxide is heated, a sharp odor is released from the gas. When the second solution reacts with sodium chromate, a yellow precipitate is formed. Write the equations of the described reactions.
Sulfur dioxide was dissolved in water and the solution was neutralized by adding sodium hydroxide. Hydrogen peroxide was added to the resulting solution, and after the reaction was completed, sulfuric acid was added. Write the equations of the described reactions.
Zinc was dissolved in very dilute nitric acid, the resulting solution was carefully evaporated and the residue was calcined. The reaction products were mixed with coke and heated. Make the reaction equations of the described transformations.
Substances released at the cathode and anode during the electrolysis of sodium iodide solution with graphite electrodes react with each other. The reaction product interacts with concentrated sulfuric acid with the release of gas, which was passed through a solution of potassium hydroxide. Write the equations of the described reactions.
The substance that is formed during the electrolysis of a bauxite melt in cryolite dissolves both in a hydrochloric acid solution and in an alkali solution with the release of the same gas. When the resulting solutions are mixed, a bulk white precipitate is formed. Write the equations of the described reactions.
Concentrated hydrochloric acid was added to lead (IV) oxide while heating. The escaping gas was passed through a heated solution of caustic potash. The solution was cooled, the oxygenated acid salt was filtered off and dried. When the resulting salt is heated with hydrochloric acid, poisonous gas is released, and when it is heated in the presence of manganese dioxide, a gas is released, which is also part of the atmosphere. Write the equations of the described reactions.
Brown precipitate obtained by the interaction of sodium sulfite with aqueous solution potassium permanganate, filtered and treated with concentrated sulfuric acid. When heated, the gas released reacts with aluminum, and the resulting substance reacts with a solution of hydrochloric acid. Write the reaction equations for the described transformations.
Calcium was heated in a hydrogen atmosphere. The reaction product was treated with water, the evolved gas was passed over heated zinc oxide, and soda ash was added to the solution. Write the equations of the described reactions.
Silver nitrate was calcined and the solid reaction product was heated in oxygen. The resulting substance dissolves in an excess of concentrated ammonia. When passing through the resulting solution of hydrogen sulfide, a black precipitate is formed. Write the equations of the described reactions.
The solid that forms when phosphorus and phosphorus pentachloride are heated is dissolved in a large amount of water. Part of the resulting solution was added to a solution of potassium permanganate acidified with sulfuric acid, while the latter became colorless. Write the equations of the described reactions.
Several granules of zinc were introduced into a vessel with concentrated sulfuric acid. The escaping gas was passed through a solution of lead (II) acetate, the precipitate was separated, calcined, and the resulting gas was introduced into interaction with an aqueous solution of potassium permanganate. Write the equations of the described reactions.
Several granules of zinc were dissolved by heating in a solution of sodium hydroxide. Nitric acid was added in small portions to the resulting solution until a precipitate formed. The precipitate was separated, dissolved in dilute nitric acid, the solution was carefully evaporated and the residue was calcined. Write the equations of the described reactions.
The gas released when copper is dissolved in hot concentrated nitric acid can interact both with the gas released when copper is treated with hot concentrated sulfuric acid and with copper. Write the equations of the described reactions.
An iron (III) chloride solution was subjected to electrolysis with graphite electrodes. A brown precipitate formed (a by-product of electrolysis) was filtered off, calcined and fused with the substance formed on the cathode. Another substance, also released at the cathode, was reacted with the product released during electrolysis at the anode; The reaction proceeds under illumination and with an explosion. Write the equations of the described reactions.
Water-insoluble white salt, which meets found in nature in the form of a mineral widely used in construction and architecture, calcined at 1000°C. Water was added to the solid residue after cooling, and the gaseous product of the decomposition reaction was passed through the resulting solution, as a result, a white precipitate formed, which dissolved upon further passing of the gas. Write the equations of the described reactions.
Test, due in an hour!
1) what volume of hydrogen will be released during the interaction of 2.3 g of sodium with ethyl alcohol, if the yield of H2 is 80%
2) Run reactions
C2H5OH-C2H4-[-CH2-CH2-]
/ \
CO2 С2H4Br
Thanks in advance!
for
the experiment proposed the following reagents: copper, hydrochloric acid and
solutions of copper sulfate (II ),
ammonium chloride, sodium hydroxide and hydrogen peroxide. It is necessary to obtain copper chloride 2
To 134 g of a solution with a mass fraction of copper chloride (ll) 2% was added an excess of a solution of silver nitrate. Determine the mass of the precipitate.
To 106 g of a solution with a mass fraction of potassium phosphate of 4% was added an excess of copper (ll) chloride solution. Determine the mass of the precipitate.
An excess of aluminum nitrate solution was added to 56 g of a solution with a mass fraction of potassium hydroxide of 6%. Determine the mass of the precipitate.
To 132.4 g of a solution with a mass fraction of lead nitrate of 5% was added an excess of sodium sulfide solution. Determine the mass of the precipitated residue.
To 63.5 g of a solution with a mass fraction of iron (ll) chloride 6% was added an excess of potassium sulfide solution. Determine the mass of the precipitate.
When barium chloride was added to a solution with a mass fraction of 4% excess aluminum sulfate solution, a precipitate weighing 4.66 g was formed. Determine the mass of the initial barium chloride solution.
When adding copper (ll) to a sodium solution with a mass fraction of 4% excess potassium hydroxide solution, a precipitate weighing 4.9 g was formed. Determine the mass of the initial salt solution.
To 240 g of a solution with a mass fraction of iron nitrate (ll) 2% was added an excess of sodium hydroxide solution. Determine the mass of the precipitate.
After passing through a solution of potassium hydroxide 1.12 liters of carbon dioxide (n.o.) received 138 g of a solution of potassium carbonate. Calculate the mass fraction of salt in the resulting solution.
In chemistry, I don’t furych (
№1) What is a pure substance in contrast to a mixture? 1) air 2) stainless steel 3) aqua regia 4) sucrose No. 2 Whatapplies to homogeneous mixtures?
2) alcohol solution
#3 A solid mixture is a mixture in which:
1) gaseous particles are distributed in liquid
2) gaseous particles are distributed in the gas
3) one liquid is fragmented in another liquid that does not dissolve it
4) solid particles are distributed in a solid
#4 What is an inhomogeneous mixture?
1) a solution of iodine in alcohol
2) copper(II) sulfate solution
3) alkali solution
No. 5 What is the name of the method of cleaning a homogeneous mixture?
1) filtering
2) cooling
3)evaporation
4) settling
№6What happens to gases in the process of dissolution with increasing temperature?
1) their solubility decreases
2) their solubility does not change
3) their solubility increases
4) their solubility first decreases and then increases
№7 Which gas dissolves only when air is passed through water?
1) only oxygen
2) only nitrogen
3) oxygen and nitrogen
4) carbon dioxide
#8 What is a gaseous mixture?
2) carbonated drink
3) a mixture of hydrogen and oxygen
HELP PLEASE!!! THANK YOU SO MUCH IN ADVANCE!!!
2Al + 3Cl 2at the cathode at the anode
4Al(NO 3) 3 2Al 2 O 3 + 12NO 2 + 3O 2
2Al 2 (SO 4) 3 2Al 2 O 3 + 6SO 2 + 3O 2
2(AlCl 3 ∙ 6H 2 O) Al 2 O 3 + 6HCl + 9H 2 O
Al 2 (SO 4) 3 + 6NaHSO 3 \u003d 2Al (OH) 3 + 6SO 2 + 3Na 2 SO 4
Al (NO 3) 3 + 4KOH (excess) \u003d K + 3KNO 3
AlCl 3 + 3 (NH 3 ∙ H 2 O) \u003d Al (OH) 3 + 3NH 4 Cl
Al 2 (SO 4) 3 + 6 (NH 3 ∙ H 2 O) \u003d 2Al (OH) 3 ↓ + 3 (NH 4) 2 SO 4
Al 2 (SO 4) 3 + 8NaOH (excess) = 2Na + 3Na 2 SO 4
AlCl 3 + 3NaOH (deficiency) = Al(OH) 3 ↓ + 3NaCl
Al(NO 3) 3 + 4KOH KAlO 2 + 3KNO 3 + 2H 2 O
KAlO 2 + 4HCl \u003d KCl + AlCl 3 + 2H 2 O
NaAlO 2 + 4HCl \u003d AlCl 3 + NaCl + 2H 2 O
KAlO 2 + H 2 O = K
NaAlO 2 + 2H 2 O \u003d Na
When solutions are mixed, hydrolysis occurs both at the cation of a weak base and at the anion of a weak acid:
2AlBr 3 + 3Na 2 CO 3 + 3H 2 O \u003d 2Al (OH) 3 ↓ + CO 2 + 6NaBr
2Al(NO 3) 3 + 3Na 2 CO 3 + 3H 2 O = 2Al(OH) 3 ↓ + 6NaNO 3 + 3CO 2
2AlCl 3 + 3Na 2 S + 6H 2 O \u003d 2Al (OH) 3 + 3H 2 S + 6NaCl
Binaryconnections.
Al 2 S 3 + 8HNO 3 \u003d Al 2 (SO 4) 3 + 8NO 2 + 4H 2 O
Al 2 S 3 + 30HNO 3 (conc. horizon) \u003d 2Al (NO 3) 3 + 24NO 2 + 3H 2 SO 4 + 12H 2 O
Al 2 S 3 + 6H 2 O \u003d 2Al (OH) 3 ↓ + 3H 2 S
Al 4 C 3 + 12H 2 O \u003d 4Al (OH) 3 + 3CH 4
AlN + 3HCl \u003d AlCl 3 + NH 3
AlN + 3H 2 O \u003d Al (OH) 3 ↓ + NH 3
Aluminum. Aluminum compounds
1. Sodium hydroxide solution was added dropwise to the solution obtained by reacting aluminum with dilute sulfuric acid until a precipitate formed. The white precipitate formed was filtered off and dried. The resulting substance was fused with sodium carbonate. Write the equations of the described reactions.
2. An excess of sodium hydroxide was added to the aluminum sulfate solution. Hydrochloric acid was added in small portions to the resulting solution, while the formation of a bulky white precipitate was observed, which dissolved with further addition of acid. A solution of sodium carbonate was added to the resulting solution. Write the equations of the described reactions.
3. The gas released during the interaction of hydrogen chloride with potassium permanganate was passed through a solution of sodium tetrahydroxoaluminate. The precipitate formed was filtered off, calcined, and the solid residue was treated with hydrochloric acid. Write the equations of the described reactions.
4. The solid substance formed during the interaction of sulfur dioxide and hydrogen sulfide, when heated, interacts with aluminum. The reaction product was dissolved in dilute sulfuric acid, and potash was added to the resulting solution. Write the equations of the described reactions.
5. The product of the interaction of sulfur with aluminum (the reaction proceeds when heated) was dissolved in cold dilute sulfuric acid and potassium carbonate was added to the solution. The resulting precipitate was separated, mixed with caustic soda and heated. Write the equations of the described reactions.
6. A solution of aluminum chloride was added to a solution of soda ash, the released substance was separated and added to a solution of caustic soda. A solution of hydrochloric acid was added dropwise to the resulting solution until the formation of a precipitate ceased, which was separated and calcined. Write the equations of the described reactions.
7. Aluminum nitrate was calcined, the reaction product was mixed with soda ash and heated to melt. The resulting substance was dissolved in nitric acid and the resulting solution was neutralized with an ammonia solution, while the isolation of a bulky gelatinous precipitate was observed. Write the equations of the described reactions.
8. The precipitate obtained by adding caustic soda to aluminum sulfate solution was separated, calcined, mixed with soda ash and heated to melt. After treatment of the residue with sulfuric acid, the initial aluminum salt was obtained. Write the equations of the described reactions.
9. Aluminum chloride was added to a solution of crystalline soda, the precipitate was separated and treated with a solution of sodium hydroxide. The resulting solution was neutralized with nitric acid, the precipitate separated and calcined. Write the equations of the described reactions.
10. The precipitate obtained by the interaction of an aluminum salt solution and alkali was calcined. The reaction product was dissolved in a concentrated hot alkali solution. Carbon dioxide was passed through the resulting solution, resulting in a precipitate. Write the equations of the described reactions.
11. A substance that is formed during the electrolysis of a bauxite melt in cryolite dissolves both in a hydrochloric acid solution and in an alkali solution with the release of the same gas. When the resulting solutions are mixed, a bulky white precipitate is formed. Write the equations of the described reactions.
12. A portion of aluminum was dissolved in dilute nitric acid, and a gaseous simple substance was released. Sodium carbonate was added to the resulting solution until the gas evolution ceased completely. The precipitate that formed was filtered off and calcined. The filtrate was evaporated, the resulting solid residue was fused with ammonium chloride. The evolved gas was mixed with ammonia and the resulting mixture was heated. Write the equations of the described reactions
13. Alumina was fused with sodium carbonate, the resulting solid was dissolved in water. Sulfur dioxide was passed through the resulting solution until the complete cessation of interaction. The precipitate formed was filtered off, and bromine water was added to the filtered solution. The resulting solution was neutralized with sodium hydroxide. Write the equations of the described reactions.
14. A sample of aluminum sulfide was treated with hydrochloric acid. In this case, gas was released and a colorless solution was formed. An ammonia solution was added to the resulting solution, and the gas was passed through a solution of lead nitrate. The precipitate thus obtained was treated with a solution of hydrogen peroxide. Write the equations of the described reactions.
15. Aluminum powder was mixed with sulfur powder, the mixture was heated, the resulting substance was treated with water, while gas was released and a precipitate formed, to which an excess of potassium hydroxide solution was added until completely dissolved. This solution was evaporated and calcined. An excess of hydrochloric acid solution was added to the resulting solid. Write the equations of the described reactions.
16. The gas released during the interaction of hydrogen chloride with Berthollet mole was introduced into the reaction with aluminum. The reaction product was dissolved in water and sodium hydroxide was added until the precipitation ceased, which was separated and calcined. Write the equations of the described reactions.
17. The gas released when a solution of hydrogen chloride with manganese (IV) oxide was heated was brought into interaction with aluminum. The reaction product was dissolved in water, and first an excess of sodium hydroxide solution was added, followed by hydrochloric acid. Write the equations of the described reactions.
18. Metallic aluminum was dissolved in a solution of sodium hydroxide. An excess of carbon dioxide was passed through the resulting solution. The resulting precipitate was calcined and the resulting product was fused with sodium carbonate. Write the equations of the described reactions.
19) Aluminum oxide was fused with soda. The resulting product was dissolved in hydrochloric acid and treated with an excess of ammonia water. The precipitate formed was dissolved in an excess of potassium hydroxide solution. Write the equations of the described reactions.
20) Aluminum oxide was fused with sodium hydroxide. The reaction product was added to an ammonium chloride solution. The released gas with a pungent odor is absorbed by sulfuric acid. The resulting middle salt was calcined. Write the equations of the described reactions.
21) Aluminum powder was heated with sulfur powder, the resulting substance was treated with water. the precipitate formed in this case was treated with an excess of potassium hydroxide solution until it was completely dissolved. A solution of aluminum chloride was added to the resulting solution, and the formation of a white precipitate was again observed. Write the equations of the described reactions.
22) The precipitate obtained by the interaction of solutions of aluminum sulfate and barium nitrate was filtered off. The filtrate was treated with sodium hydroxide in a molar ratio of 1: 3. The precipitate was separated and calcined. The resulting substance was treated with an excess of hydrochloric acid solution. Write the equations of the described reactions.
23) When a solution of aluminum sulfate reacted with a solution of potassium sulfide, a gas was released, which was passed through a solution of potassium hexahydroxoaluminate. The precipitate formed was filtered off, washed, dried and heated. The solid residue was fused with caustic soda. Write the equations of the described reactions.
24) Aluminum powder was mixed with sulfur and heated. The resulting substance was placed in water. The resulting precipitate was divided into two parts. Hydrochloric acid was added to one part, and sodium hydroxide solution was added to the other. Write the equations of the described reactions.
25) Metallic aluminum was dissolved in a solution of sodium hydroxide. An excess of carbon dioxide was passed through the resulting solution. The precipitate formed was calcined and the resulting product was dissolved in dilute sulfuric acid. Write the equations of the described reactions.
26) When aluminum oxide and nitric acid reacted, a salt was formed. The salt was dried and calcined. The residue formed during calcination was subjected to electrolysis in molten cryolite. The resulting metal was heated with concentrated potassium hydroxide and potassium nitrate. At the same time, a gas with a pungent odor was released. Write the equations of the described reactions.
27) Aluminum powder was added to the sodium hydroxide solution. An excess of carbon dioxide was passed through the solution of the obtained substance. The precipitate formed was separated and calcined. The resulting product was fused with sodium carbonate. Write the equations of the described reactions.
28) Powder of metallic aluminum was mixed with solid iodine, and a few drops of water were added. Sodium hydroxide solution was added to the resulting salt until a precipitate formed. The resulting precipitate was dissolved in hydrochloric acid. With the subsequent addition of sodium carbonate solution, precipitation is again observed. Write the equations of the described reactions.
29) Aluminum was dissolved in hydrochloric acid. An excess of potassium carbonate solution was added to the resulting solution. The precipitate that formed was dissolved in an excess of caustic potassium solution, and the released gas was passed over hot coal. Write the equations of the described reactions.
30) Aluminum was dissolved in an aqueous solution of hot sodium hydroxide. dilute hydrochloric acid was added dropwise to the resulting solution until precipitation ceased. The gas released during the reaction period was passed over hot copper (II) oxide. The resulting simple substance was dissolved in dilute nitric acid. Write the equations of the described reactions.
31) Aluminum has reacted with. The resulting mixture of substances was dissolved in a concentrated sodium hydroxide solution and filtered. The solid was burned under a chlorine atmosphere and the filtrate was treated with a concentrated aluminum chloride solution. Write the equations of the described reactions.
Aluminum. Aluminum compounds
1) 2Al + 3H 2 SO 4 = Al 2 (SO 4) 3 + 3H 2
Al 2 (SO 4) 3 + 6NaOH (lack) \u003d 2Al (OH) 3 ↓ + 3Na 2 SO 4
2Al(OH) 3 Al 2 O 3 + 3H 2 O
2) Al 2 (SO 4) 3 + 8NaOH (excess) = 2Na + 3Na 2 SO 4
Na + HCl (lack) \u003d Al (OH) 3 ↓ + NaCl + H 2 O
Al(OH) 3 + 3НCl = AlCl 3 + 3H 2 O
2AlCl 3 + 3Na 2 CO 3 + 3H 2 O \u003d 2Al (OH) 3 ↓ + 6NaCl + 3CO 2
3) 2KMnO 4 + 16HCl = 2MnCl 2 + 5Cl 2 + 2KCl + 8H 2 O
2Na + Cl 2 \u003d 2Al (OH) 3 ↓ + NaCl + NaClO + H 2 O
2Al(OH) 3 Al 2 O 3 + 3H 2 O
Al 2 O 3 + 6HCl \u003d 2AlCl 3 + 3H 2 O
4) SO 2 + 2H 2 S \u003d 3S ↓ + 2H 2 O
2Al + 3S = Al 2 S 3
Al 2 S 3 + H 2 SO 4 \u003d Al 2 (SO 4) 3 + H 2 S
Al 2 (SO 4) 3 + 3K 2 CO 3 + 3H 2 O \u003d 2Al (OH) 3 ↓ + 3CO 2 + 3K 2 SO 4
5) 2Al + 3S Al 2 S 3
Al 2 S 3 + 3H 2 SO 4 \u003d Al 2 (SO 4) 3 + 3H 2 S
Al 2 (SO 4) 3 + 3K 2 CO 3 + 3H 2 O \u003d 2Al (OH) 3 ↓ + 3CO 2 + 3K 2 SO 4
Al(OH) 3 + NaOH NaAlO 2 + 2H 2 O
6) 2AlCl 3 + 3Na 2 CO 3 + 3H 2 O = 2Al(OH) 3 ↓ + 6NaCl + 3CO 2
Na + HCl (lack) \u003d Al (OH) 3 ↓ + NaCl + H 2 O
2Al(OH) 3 Al 2 O 3 + 3H 2 O
7) 4Al(NO 3) 3 2Al 2 O 3 + 12NO 2 + 3O 2
Al 2 O 3 + Na 2 CO 3 2NaAlO 2 + CO 2
NaAlO 2 + 4HNO 3 \u003d Al (NO 3) 3 + NaNO 3 + 2H 2 O
Al(NO 3) 3 + 3(NH 3 ∙ H 2 O) = Al(OH) 3 ↓ + 3NH 4 Cl
8) Al 2 (SO 4) 3 + 6NaOH \u003d 2Al (OH) 3 ↓ + 3Na 2 SO 4
2Al(OH) 3 Al 2 O 3 + 3H 2 O
Al 2 O 3 + Na 2 CO 3 2NaAlO 2 + CO 2
2NaAlO 2 + 4H 2 SO 4 \u003d Al 2 (SO 4) 3 + Na 2 SO 4 + 4H 2 O
9) 2AlCl 3 + 3Na 2 CO 3 + 3H 2 O \u003d 2Al (OH) 3 ↓ + 6NaCl + 3CO 2
Al(OH) 3 + NaOH = Na
Na + HNO 3 (deficiency) = Al(OH) 3 ↓ + NaNO 3 + H 2 O
2Al(OH) 3 Al 2 O 3 + 3H 2 O
10) AlCl 3 + 3NaOH \u003d Al (OH) 3 ↓ + 3NaCl
2Al(OH) 3 Al 2 O 3 + 3H 2 O
Al 2 O 3 + 2NaOH + 3H 2 O \u003d 2Na
From the rehearsal test options (V.N. Doronkin "Preparation for the Unified State Examination -2012")
1. The solution obtained by the interaction of copper with concentrated nitric acid was evaporated and the precipitate was calcined. The gaseous products of the decomposition reaction are completely absorbed by water, and hydrogen is passed over the solid residue. Write the equations of the described reactions.
C the content of the answer
1) Cu + 4HNO 3 (conc) → Cu (NO 3) 2 + 2NO 2 + 2H 2 O
2) 2 Cu(NO 3) 2 → 2CuO + 4NO 2 + O 2
3) CuO + H 2 → Cu + H 2 O
4) 4NO 2 + 2H 2 O + O 2 → 4НNO 3
2. A simple substance obtained by heating calcium phosphate with coke and silicon oxide, fused with calcium metal. The reaction product was treated with water, and the evolved gas was collected and passed through a hydrochloric acid solution. Write the equations of the described reactions.
C the content of the answer
1) Ca 3 (PO 4) 2 ↓ + 5C + 3SiO 2 → 3CaSiO 3 + 2P + 5CO
2) 2P + 3Ca → Ca 3 P 2
3) Ca 3 P 2 + 6H 2 O → 3Ca (OH) 2 + 2PH 3
4) PH 3 + HC1 → PH 4 C1
3) A solution of ferric chloride was treated with a solution of sodium hydroxide. The precipitate that formed was separated and heated. The solid reaction product was mixed with soda ash and calcined. Sodium nitrate and sodium hydroxide were added to the remaining substance and heated at a high temperature for a long time.
Write the equations of the described reactions.
C the content of the answer
1) FeС1 3 + 3NаОН→Fe(ОН) 3 ↓+3NаС1
2) 2Fe (OH) 3 → Fe 2 O 3 ↓ + 3H 2 O
3) Fe 2 O 3 + Na 2 CO 3 → 2NaFeO 2 + CO 2
4) 2NaFeO 2 + 3NaNO 3 + 2NaOH → 2Na 2 FeO 4 + 2NaNO 2 + H 2 O
4) Concentrated hydrochloric acid was added to lead (IV) oxide while heating. The released gas was passed through a heated solution of caustic potash. The salt of the oxygen-containing acid, which precipitated when the solution was cooled, was filtered off and dried. When the resulting salt is heated with hydrochloric acid, a poisonous gas is released, and when it is heated in the presence of manganese dioxide, a gas that is part of the atmosphere Write the equations of the described reactions.
C the content of the answer
1) 4HCl + PbO 2 → PbC1 2 ↓ + 2H 2 O + Cl 2
2) 6KOH + 3Cl 2 → 5KS1 + KS1O 3 + 3H 2 O
3) KC1O 3 + 6HC1 → KC1 + 3C1 2 + 3H 2 O
4) 2KS1O 3 → 2KS1 + 3O 2
5) An excess of sodium hydroxide solution was added to the aluminum sulfate solution. hydrochloric acid was added in small portions to the resulting solution, while the formation of a bulky white precipitate was observed, which dissolved with further addition of acid. A solution of sodium carbonate was added to the resulting solution. Write the equations of the written reactions.
1) A1 2 (SO 4) 3 + 8NaOH → 2Na + 3Na 2 SO 4 or A1 2 (SO 4) 3 + 12NaOH → 2Na 3 + 3Na 2 SO 4
2) Na 3 + 3HC1 → 3NaC1 + Al (OH) 3 ↓ + 3H 2 O
3) Al (OH) 3 ↓ + 3HC1 → A1C1 3 + 3H 2 O
4) 2AlC1 3 + 3H 2 O + 3Na 2 CO 3 → 3CO 2 + 2A1 (OH) 3 ↓ + 6NaC1
6) After briefly heating an unknown orange powder, a spontaneous reaction begins, which is accompanied by a change in color to green, the release of gas and sparks. The solid residue was mixed with caustic potash and heated, the resulting substance was added to a dilute solution of hydrochloric acid, and a green precipitate formed, which dissolves in an excess of acid. Write the equations of the described reactions.
1) (NH 4) 2 Cr 2 O 7 → Cr 2 O 3 + N 2 + 4H 2 O
2) Cr 2 O 3 + 4KOH→2KCrO 2 + H 2 O
3) KCrO 2 + HCl + H 2 O → Cr (OH) 3 ↓ + KCl
4) Cr(OH) 3 + 3HCl (excess) → CrCl 3 + 3H 2 O
7) The nitric acid was neutralized with baking soda, the neutral solution was carefully evaporated, and the residue was calcined. The resulting substance was introduced into a solution of potassium permanganate acidified with sulfuric acid. while the solution became colorless. The nitrogen-containing reaction product was placed in a sodium hydroxide solution and zinc dust was added, and a gas with a sharp characteristic odor was released. Write the equations of the described reactions.
1) NaHCO 3 + HNO 3 → NaNO 3 + CO 2 + H 2 O
2) 2 NaNO 3 → 2NaNO 2 + O 2
3) 5 NaNO 2 + 2KMnO 4 + 3H 2 SO 4 → 5NaNO 3 + K 2 SO 4 + Mn 2 SO 4 + 3H 2 O
4) NaNO 3 + 4Zn + 7NaOH + 6H 2 O → NH 3 + 4Na 2
8) The substance obtained at the cathode during the electrolysis of a melt of sodium chloride was burned in oxygen. The resulting product was sequentially treated with sulfur dioxide and barium hydroxide solution. Write the equations of the described reactions.
1) 2NaCl→2Na+Cl 2
2) 2Na + O 2 →Na 2 O 2
3) Na 2 O 2 + SO 2 → Na 2 SO 4
4) Na 2 SO 4 + Ba(OH) 2 → BaSO 4 ↓ + 2NaOH
9) Quicklime was calcined with an excess of coke. The reaction product after treatment with water is used to absorb sulfur dioxide and carbon dioxide. Write the equations of the described reactions
1) CaO + 3C → CaC 2 + CO
2) CaC 2 + 2H 2 O → Ca (OH) 2 ↓ + C 2 H 2
3) Ca (OH) 2 + CO 2 →CaCO 3 ↓ + H 2 O or Ca (OH) 2 + 2CO 2 → Ca (HCO 3) 2
4) Ca (OH) 2 + SO 2 → CaSO 3 ↓ + H 2 O or Ca (OH) 2 + 2SO 2 → Ca (HSO 3) 2
10) A copper wire was introduced into heated concentrated sulfuric acid, and the escaping gas was passed through an excess of caustic soda. The solution was carefully evaporated, the solid residue was dissolved in water and heated with powdered sulfur. The unreacted sulfur was separated by filtration, and sulfuric acid was added to the solution, while a precipitate was observed and a gas with a pungent odor was released.
Write the equations of the described reactions
1) Cu + 2H 2 SO 4 → CuSO 4 + SO 2 + 2H 2 O
2) 2NaOH + SO 2 → Na 2 SO 3 + H 2 O
3) Na 2 SO 3 + S → Na 2 S 2 O 3
4) Na 2 S 2 O 3 + H 2 SO 4 → Na 2 SO 4 + SO 2 + S ↓ + H 2 O
11) The substance formed during the fusion of magnesium with silicon was treated with water, as a result a precipitate formed and a colorless gas was released. The precipitate was dissolved in hydrochloric acid, and the gas was passed through a solution of potassium permanganate. in this case, two water-insoluble binary compounds were formed. Write the equations of the described reactions
1) Si + 2Mg = Mg 2 Si
2) Mg 2 Si + 4H 2 O \u003d 2Mg (OH) 2 + SiH 4
3) Mg (OH) 2 + 2HCl → MgCl 2 + 2H 2 O
4) 3SiH 4 + 8KMnO 4 → 8MnO 2 ↓+ 3SiO 2 ↓ +8KOH+ 2H 2 O
12 ) A solution of hydrochloric acid was added to a water-insoluble white salt, which occurs in nature in the form of a mineral widely used in construction and architecture. As a result, the salt dissolved and a gas was released, which, when passed through lime water, precipitated a white precipitate, which dissolved upon further passage of the gas. When the resulting solution is boiled, a precipitate forms and a gas is released. Write the equations of the described reactions.
1) CaCO 3 + 2HC1 → CaC1 2 + CO 2 + H 2 O
2) Ca (OH) 2 + CO 2 →CaCO 3 ↓ + H 2 O
3) CaCO 3 ↓ + H 2 O + CO 2 → Ca (HCO 3) 2
4) Ca (HCO 3) 2 → CaCO 3 ↓ + H 2 O + CO 2
13) The salt obtained by the interaction of zinc oxide with sulfuric acid was calcined at 800 0 C. The solid reaction product was treated with a concentrated alkali solution and carbon dioxide was passed through the resulting solution. Write the equations of the described reactions.
1) ZnO + H 2 SO 4 → ZnSO 4 + H 2 O
2) 2 ZnSO 4 → ZnO + 2SO 2 + O 2
3) ZnO+2NaOH+H3O→Na 2
4) Na 2 + 2CO 2 → 2NaHCO 3 + Zn (OH) 2 ↓ or Na 2 + CO 2 → Na 2 CO 3 + Zn (OH) 2 ↓ + H 2 O
14) Soda ash was added to a solution of trivalent chromium sulfate. The precipitate formed was separated, transferred to a sodium hydroxide solution, bromine was added and heated. After neutralization of the reaction products with sulfuric acid, the solution acquires an orange color, which changes to green after passing sulfur dioxide through the solution. Write the equations of the described reactions
1) Cr 2 (SO 4) 3 + 3Na 2 CO 3 + 3H 2 O → 2Cr (OH) 3 ↓ + 3Na 2 SO 4 + 3CO 2
2) 2Cr(OH) 3 + 10NaOH + 3Br 2 → 2Na 2 CrO 4 + 6NaBr + 8H 2 O
3) 2Na 2 CrO + H 2 SO 4 → Na 2 Cr 2 O 7 + Na 2 SO 4 + H 2 O
4) Na 2 Cr 2 O 7 + 3SO 2 + H 2 SO 4 → Na 2 SO 4 + Cr 2 (SO 4) 3 + H 2 O
15) Phosphine was passed through a hot solution of concentrated nitric acid. The reaction products were neutralized with quicklime, the precipitate was separated, mixed with coke and silica, and calcined. The reaction product, which glows in the dark, was heated in a sodium hydroxide solution. Write the equations of the described reactions
1) PH 3 + 8HNO 3 (clnts) → H 3 RO 4 + 8NO 2 + 4H 2 O
2) 2H 3 RO 4 + 3CaO → Ca 3 (RO 4) 2 ↓ + 3H 2 O and 2HNO 3 + CaO → Ca (NO 3) 2 + H 2 O
3) Ca 3 (PO 4) 2 ↓ + 5C + 3SiO 2 → 3CaSiO 3 + 2P + 5CO
4) P 4 +3 NaOH + 3H 2 O → 3NaH 2 PO 2 + PH 3
16) The black powder, which was formed when the red metal was burned in excess air, was dissolved in 10% sulfuric acid. Alkali was added to the resulting solution, and the resulting blue precipitate was separated and dissolved in an excess of ammonia solution. Write the equations of the described reactions.
1) 2Cu+О 3 →2CuO
2) CuO + H 2 SO 4 → CuSO 4 + H 2 O
3) CuSO 4 + 2NaOH → Cu (OH) 2 ↓ + Na 2 SO 4
4) Cu (OH) 2 ↓ + 4NH 3 ∙ H 2 O → (OH) 2 + 4H 2 O
17) Red phosphorus was burned in an atmosphere of chlorine. The reaction product was treated with excess water and powdered zinc was added to the solution. The escaping gas was passed over a heated plate of oxidized copper. Write the equations of the described reactions
1) 2P + 5Cl 2 → 2PCl 5
2) PCl 5 + 4H 2 O → H 3 PO 4 + 5HCl
3) 3Zn + 2H 3 PO 4 → Zn 3 (PO 4) 2 ↓ + 3H 2 and Zn + 2HCl → ZnCl 2 + H 2
4) CuO+H 2 →Cu+H 2 O
18) The substance obtained at the anode during the electrolysis of a solution of sodium iodyl on inert electrodes was introduced into a reaction with potassium. The reaction product was heated with concentrated sulfuric acid and the evolved gas was passed through a hot solution of potassium chromate. Write the equations of the described reactions
1) 2KI + 2H 2 O → 2KOH + I 2 ↓
2) I 2 +2K → 2KI
3) 8KI+5H 2 SO 4 →4 I 2 ↓+H 2 S+4K 2 SO 4 +4H 2 O or 8KI+9H 2 SO 4 →4 I 2 ↓+H 2 S+8KHSO 4 +4H 2 O
4) 3H 2 S+ 2K 2 CrO 4 +2H 2 O→2Cr(OH) 3 ↓+3S↓+4KOH
19) The gas formed as a result of the reaction of hydrogen chloride with a hot solution of potassium chromate interacts with iron. The reaction product was dissolved in water, and sodium sulfide was added thereto. The lighter substance from the resulting insoluble compounds was separated and reacted with concentrated sulfuric acid by heating. Write the equations of the described reactions.
1) 2K 2 CrO 4 + 16HCl → 4KCl + 2CrCl 7 + 3Cl 2 + H 2 O
2) 2Fe + 3Cl 2 → 2FeCl 3
3) 2FeCl 3 +3Na 2 S→S↓+FeS↓+6NaCl
4) S + 2H 2 SO 4 → 2SO 2 + 2H 2 O
20) Two salts color the flame purple. One of them is colorless, and when it is slightly heated with concentrated sulfuric acid, a liquid is distilled off, in which copper dissolves; the last transformation is accompanied by the evolution of brown gas. When the second salt of the sulfuric acid solution is added to the solution, the yellow color of the solution changes to orange, and when the resulting solution is neutralized with alkali, the original color is restored. Write the equations of the described reactions
1) KNO 3 + 2H 2 SO 4 → KHSO 4 + HNO 3
2) Cu + 4HNO 3 (conc) → Cu (NO 3) 2 + 2NO 2 + 2H 2 O
3) 2K 2 CrO 4 + H 2 SO 4 → K 2 Cr 2 O 7 + K 2 SO 4 + H 2 O
4) K 2 Cr 2 O 7 + 2KOH → 2K 2 CrO 4 + H 2 O
1) Copper nitrate was calcined, the resulting solid precipitate was dissolved in sulfuric acid. Hydrogen sulfide was passed through the solution, the resulting black precipitate was calcined, and the solid residue was dissolved by heating in concentrated nitric acid.
2) Calcium phosphate was fused with coal and sand, then the resulting simple substance was burned in an excess of oxygen, the combustion product was dissolved in an excess of caustic soda. A solution of barium chloride was added to the resulting solution. The resulting precipitate was treated with an excess of phosphoric acid.
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Ca 3 (PO 4) 2 → P → P 2 O 5 → Na 3 PO 4 → Ba 3 (PO 4) 2 → BaHPO 4 or Ba (H 2 PO 4) 2 Ca 3 (PO 4) 2 + 5C + 3SiO 2 → 3CaSiO 3 + 2P + 5CO |
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3) Copper was dissolved in concentrated nitric acid, the resulting gas was mixed with oxygen and dissolved in water. Zinc oxide was dissolved in the resulting solution, then a large excess of sodium hydroxide solution was added to the solution.
4) Dry sodium chloride was treated with concentrated sulfuric acid at low heating, the resulting gas was passed into a solution of barium hydroxide. A solution of potassium sulfate was added to the resulting solution. The resulting precipitate was fused with coal. The resulting substance was treated with hydrochloric acid.
5) A sample of aluminum sulfide was treated with hydrochloric acid. In this case, gas was released and a colorless solution was formed. An ammonia solution was added to the resulting solution, and the gas was passed through a solution of lead nitrate. The precipitate thus obtained was treated with a solution of hydrogen peroxide.
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Al(OH) 3 ←AlCl 3 ←Al 2 S 3 → H 2 S → PbS → PbSO 4 Al 2 S 3 + 6HCl → 3H 2 S + 2AlCl 3 |
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6) Aluminum powder was mixed with sulfur powder, the mixture was heated, the resulting substance was treated with water, gas was released and a precipitate formed, to which an excess of potassium hydroxide solution was added until complete dissolution. This solution was evaporated and calcined. An excess of hydrochloric acid solution was added to the resulting solid.
7) A solution of potassium iodide was treated with a solution of chlorine. The resulting precipitate was treated with sodium sulfite solution. First, a solution of barium chloride was added to the resulting solution, and after separating the precipitate, a solution of silver nitrate was added.
8) A gray-green powder of chromium (III) oxide was fused with an excess of alkali, the resulting substance was dissolved in water, and a dark green solution was obtained. Hydrogen peroxide was added to the resulting alkaline solution. A yellow solution was obtained, which, when sulfuric acid is added, acquires Orange color. When hydrogen sulfide is passed through the resulting acidified orange solution, it becomes cloudy and turns green again.
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Cr 2 O 3 → KCrO 2 → K → K 2 CrO 4 → K 2 Cr 2 O 7 → Cr 2 (SO 4) 3 Cr 2 O 3 + 2KOH → 2KCrO 2 + H 2 O |
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9) Aluminum was dissolved in a concentrated solution of potassium hydroxide. Carbon dioxide was passed through the resulting solution until the precipitation ceased. The precipitate was filtered off and calcined. The resulting solid residue was fused with sodium carbonate.
10) Silicon was dissolved in a concentrated solution of potassium hydroxide. An excess of hydrochloric acid was added to the resulting solution. The cloudy solution was heated. The separated precipitate was filtered off and calcined with calcium carbonate. Write the equations of the described reactions.
11) Copper(II) oxide was heated in a stream of carbon monoxide. The resulting substance was burned in an atmosphere of chlorine. The reaction product was dissolved in water. The resulting solution was divided into two parts. A solution of potassium iodide was added to one part, a solution of silver nitrate was added to the second. In both cases, the formation of a precipitate was observed. Write the equations for the four described reactions.
12) Copper nitrate was calcined, the resulting solid was dissolved in dilute sulfuric acid. The resulting salt solution was subjected to electrolysis. The substance released at the cathode was dissolved in concentrated nitric acid. The dissolution proceeded with evolution of brown gas. Write the equations for the four described reactions.
13) Iron was burned in an atmosphere of chlorine. The resulting material was treated with an excess of sodium hydroxide solution. A brown precipitate formed, which was filtered off and calcined. The residue after calcination was dissolved in hydroiodic acid. Write the equations for the four described reactions.
14) Powder of metallic aluminum was mixed with solid iodine and a few drops of water were added. Sodium hydroxide solution was added to the resulting salt until a precipitate formed. The resulting precipitate was dissolved in hydrochloric acid. Upon subsequent addition of sodium carbonate solution, precipitation was again observed. Write the equations for the four described reactions.
15) As a result of incomplete combustion of coal, a gas was obtained, in the flow of which iron oxide (III) was heated. The resulting substance was dissolved in hot concentrated sulfuric acid. The resulting salt solution was subjected to electrolysis. Write the equations for the four described reactions.
16) Some amount of zinc sulfide was divided into two parts. One of them was treated with nitric acid, and the other was fired in air. During the interaction of the evolved gases, a simple substance was formed. This substance was heated with concentrated nitric acid, and a brown gas was released. Write the equations for the four described reactions.
17) Potassium chlorate was heated in the presence of a catalyst, and a colorless gas was released. By burning iron in an atmosphere of this gas, iron scale was obtained. It was dissolved in an excess of hydrochloric acid. To the solution thus obtained was added a solution containing sodium dichromate and hydrochloric acid.
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1) 2KClO 3 → 2KCl + 3O 2 2) ЗFe + 2O 2 → Fe 3 O 4 3) Fe 3 O 4 + 8HCI → FeCl 2 + 2FeCl 3 + 4H 2 O 4) 6 FeCl 2 + Na 2 Cr 2 O 7 + 14 HCI → 6 FeCl 3 + 2 CrCl 3 + 2NaCl + 7H 2 O 18) Iron burned in chlorine. The resulting salt was added to a solution of sodium carbonate, and a brown precipitate fell out. This precipitate was filtered off and calcined. The resulting substance was dissolved in hydroiodic acid. Write the equations for the four described reactions. 1) 2Fe + 3Cl 2 → 2FeCl 3 2) 2FeCl 3 + 3Na 2 CO 3 → 2Fe (OH) 3 + 6NaCl + 3CO 2 3) 2Fe(OH) 3 Fe 2 O 3 + 3H 2 O 4) Fe 2 O 3 + 6HI → 2FeI 2 + I 2 + 3H 2 O |
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19) A solution of potassium iodide was treated with an excess of chlorine water, while observing first the formation of a precipitate, and then its complete dissolution. The iodine-containing acid thus formed was isolated from the solution, dried, and gently heated. The resulting oxide reacted with carbon monoxide. Write down the equations of the described reactions.
20) Chromium(III) sulfide powder was dissolved in sulfuric acid. In this case, gas was released and a colored solution was formed. An excess of ammonia solution was added to the resulting solution, and the gas was passed through lead nitrate. The resulting black precipitate turned white after treatment with hydrogen peroxide. Write down the equations of the described reactions.
21) Aluminum powder was heated with sulfur powder, the resulting substance was treated with water. The resulting precipitate was treated with an excess of concentrated potassium hydroxide solution until it was completely dissolved. A solution of aluminum chloride was added to the resulting solution, and the formation of a white precipitate was again observed. Write down the equations of the described reactions.
22) Potassium nitrate was heated with powdered lead until the reaction ceased. The mixture of products was treated with water, and then the resulting solution was filtered. The filtrate was acidified with sulfuric acid and treated with potassium iodide. The released simple substance was heated with concentrated nitric acid. In the atmosphere of the resulting brown gas, red phosphorus was burned. Write down the equations of the described reactions.
23) Copper was dissolved in dilute nitric acid. An excess of ammonia solution was added to the resulting solution, observing first the formation of a precipitate, and then its complete dissolution with the formation of a dark blue solution. The resulting solution was treated with sulfuric acid until the characteristic blue color of copper salts appeared. Write down the equations of the described reactions.
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1) 3Cu + 8HNO 3 → 3Cu (NO 3) 2 + 2NO + 4H 2 O 2) Cu (NO 3) 2 + 2NH 3 H 2 O → Cu (OH) 2 + 2NH 4 NO 3 3) Cu (OH) 2 + 4NH 3 H 2 O → (OH) 2 + 4H 2 O 4) (OH) 2 + 3H 2 SO 4 → CuSO 4 + 2 (NH 4) 2 SO 4 + 2H 2 O |
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24) Magnesium was dissolved in dilute nitric acid, and no evolution of gas was observed. The resulting solution was treated with an excess of potassium hydroxide solution while heating. The resulting gas was burned in oxygen. Write down the equations of the described reactions.
25) A mixture of potassium nitrite and ammonium chloride powders was dissolved in water and the solution heated gently. The released gas reacted with magnesium. The reaction product was added to an excess of hydrochloric acid solution, and no gas evolution was observed. The resulting magnesium salt in solution was treated with sodium carbonate. Write down the equations of the described reactions.
26) Aluminum oxide was fused with sodium hydroxide. The reaction product was added to an ammonium chloride solution. The released gas with a pungent odor is absorbed by sulfuric acid. The middle salt thus formed was calcined. Write down the equations of the described reactions.
27) Chlorine reacted with a hot solution of potassium hydroxide. When the solution was cooled, crystals of Berthollet salt precipitated. The resulting crystals were added to a hydrochloric acid solution. The resulting simple substance reacted with metallic iron. The reaction product was heated with a new sample of iron. Write down the equations of the described reactions.
28) Copper was dissolved in concentrated nitric acid. An excess of ammonia solution was added to the resulting solution, observing first the formation of a precipitate, and then its complete dissolution. The resulting solution was treated with an excess of hydrochloric acid. Write down the equations of the described reactions.
29) Iron was dissolved in hot concentrated sulfuric acid. The resulting salt was treated with an excess of sodium hydroxide solution. The brown precipitate formed was filtered off and dried. The resulting substance was fused with iron. Write the equations for the four described reactions.
30) As a result of incomplete combustion of coal, a gas was obtained, in the flow of which iron oxide (III) was heated. The resulting substance was dissolved in hot concentrated sulfuric acid. The resulting salt solution was treated with an excess of potassium sulfide solution.
31) Some amount of zinc sulfide was divided into two parts. One of them was treated with hydrochloric acid, and the other was fired in air. During the interaction of the evolved gases, a simple substance was formed. This substance was heated with concentrated nitric acid, and a brown gas was released.
32) Sulfur was fused with iron. The reaction product was treated with hydrochloric acid. The resulting gas was burned in an excess of oxygen. The combustion products were absorbed by an aqueous solution of iron(III) sulfate.
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