Question

A metal X forms a salt XSO₄. The salt XSO₄ forms a clear solution in water which reacts with sodium hydroxide solution to form a blue precipitate Y. Metal X is used in making electric wire and alloys like brass.
(a) What do you think metal X could be?
(b) Write the name, formula and colour of salt XSO₄.
(c) What is the blue precipitate Y?
(d) Write a chemical equation of the reaction which takes place when salt XSO₄ reacts with sodium hydroxide solution. Give the state symbols of all the reactants and products which occur in the above equation.

Answer 1

(a) Metal X could be copper (Cu).

(b) The salt XSO₄ is copper sulphate; its formula is CuSO₄ and it is blue in colour.

(c) Copper hydroxide [Cu(OH)₂] is the blue precipitate.

(d) CuSO₄ (aq) + 2NaOH (aq) → Cu(OH)₂ (s) + Na₂SO₄ (aq)