Write a balanced chemical equation for the preparation of each of the following salts:
(i) Copper carbonate
(ii) Ammonium sulphate crystals
(i) CuSO4 + Na2CO3 ⟶ Na2SO4 + CuCO3
(ii) 2NH4OH + H2SO4 ⟶ (NH4)2SO4 + 2H2O