Zinc reacts with copper (II) sulphate to produce zinc sulphate and copper. As zinc is placed higher than copper in the electrochemical series, zinc is more electropositive than copper. Thus, the black zinc metal dissolved indicates that zinc ionizes to form zinc ions and displaces the copper (II) ions from 1 M CuSO_4 solution. The reddish-brown precipitate formed indicates copper is deposited after displaced by zinc. At first, the blue colour of 1 M CuSO_4 solution indicates the presence of copper (II) ions. The blue intensity of 1 M CuSO_4 solution decreases as the number of copper (II) ions in the solution decreases. This is due to copper is displaced by zinc from its solution. The colourless solution formed is zinc sulphate solution. …show more content…
Reactions of ionic compounds Reaction between CaCl_2 and Na_3 PO_4 Calcium chloride reacts with sodium phosphate to produce calcium phosphate and sodium chloride. The white precipitate formed is calcium phosphate. As calcium ions combine with phosphate ions, the solubility of calcium phosphate decreases. Hence, calcium phosphate is an insoluble salt. In this reaction, the cations in calcium chloride and sodium phosphate displace each other. Calcium ions and sodium ions displace each other to form new compounds which is calcium phosphate and sodium chloride. Since this reaction involves the cations of the two ionic reactants which is calcium chloride and sodium phosphate, hence it is a double replacement