Make up the equations o f the reactionss

Cu₂S + O₂ =

Cu₂S + Cu₂О =

Cu + H₂SO₄ =

Cu + HNO₃ =

CuSO₄ + NaOH =

Cu(OH)₂ + H =

Cu(OH)₂ + OH =

Cu(OH)₂

CuSO₄ + NH₃ =

CuCl₂ + KCl =

CuSO₄ + KI =

Cu + CuCl₂ + HCl =

CuCl + HCl =

CuCl + NaOH =

CuCl + NH₃ =

Cu₂O + HCl =

Cu₂O + H₂SO₄ =

Ag + H₂S + O₂ =

Ag + HNO₃ =

AgNO₃ + NaOH =

Ag₂O + HNO₃ =

Ag₂O + H₂O =

AgCl + NH₃ =

AgBr + Na₂S₂O₃ =

Au + HNO₃ + HCl =

Au + Cl₂ + HCl =

AuCl₃ + NaOH =

Au(OH)₃ + NaOH =

Au(OH)₃ + HCl =

Au(OH)₃

AuCl₃ + HCl =

Au₂O₃

Experimental section

1. Materials and equipment: copper sawdust, crystalline copper (II) chloride, solutions of hydrochloric acid, sulfuric acid, nitric acid, copper (ІІ) sulphate, silver nitrate, sodium hydroxide, sodium sulphite, potassium chloride, potassium bromide, potassium iodide, glucose, concentrated hydrochloric acid, sulfuric acid, nitric acid, 100 mls beakers, test tubes, glass rods.

2. Chemical properties of copper

2.1. Put a slice of metal copper into each of three test tubes and add 5-6 drops of 1 M solutions: of hydrochloric acid into the first, of sulfuric acid into the second, of nitric acid into the third one. In what test tubes did the blue colouring of solution appear? Give the equations of the relevant reactions.

Place off weak acids, keeping in the test tubes slices of metallic copper. Wash out copper with water and add 5-6 drops of concentrated solutions of the same acids. Observe at first at ambient temperature, and then when cautiously heated up, in what test tubes does the chemical reaction proceed. Give the equations of the relevant reactions.

2.2. Place 3-4 drops of 0,5N copper (ІІ) sulphate solution into each of the four test tubes and add the same volume of alkali. What colour do the precipitate formed have? Then cautiously heat the first test tube, add 5-6 drops of 2 M sodium hydroxide solution to the second, the same volume of 1 M sulfuric acid solution to the third, the same volume of 1 M ammonia solution to the fourth. What can you observe? In what cases did the precipitate dissolve? Give the equations of the relevant reactions.

2.3. Put 5-6 drops of 0,5N copper (ІІ) sulphate solution into a test tube and add the excess amount of 0,5N potassium iodide solution. What can you observe? Then add 0,5N sodium sulphite solution to the mixture until it loses colour. Divide the mixture in two parts. Add 1 M sodium hydroxide solution to the first one, and 1 M ammonia solution to the second. What can you observe? Give the equations of the relevant reactions.

2.4. Put 3-4 drops of 0,5N copper (ІІ) sulphate solution into a test tube, add 5-6 drops of 1 M sodium hydroxide solution and 3-4 drops of 0,5 M glucose solution. Mix the mixture well, and then heat up. Explain the formation of the yellow precipitate and its further transformation to the red precipitate. Give the equations of the relevant reactions.

2.5. Put 1 g of crystalline copper (II) chloride, 0,5 g of copper sawdust into a test tube and add 3-4 mls of diluted hydrochloric acid. Boil the mixture for 2-3 minutes. Place the solution formed in a beaker, which contains 20 mls of cold water. What substance precipitates? Let the precipitate to settle, pour off the liquid and divide the precipitate in two parts. Add concentrated hydrochloric acid to the first part, and 2 M sodium hydroxide solution to the second one. What can you observe? Give the equations of the relevant reactions.