Question

What do you observe when sodium hydroxide is added to zinc sulphate solution first a little, then in excess.

Answer 1

Explanation:

It can be prepared by adding sodium hydroxide solution, but not in excess, to a solution of any zinc salt. A white precipitate will be seen: Zn2+ + 2 OH− → Zn(OH)2.

Other cations: Cadmium hydroxide

Other anions: Zinc oxide

Solubility in water: slightly soluble

Chemical formula: Zn(OH)2

Answer 2

A white gelatinous Percipitate is formed which is soluble in excess of sodium hydroxide.

ZnSO4 +2NaOH --- Zn(OH) 2 + NaSO4

Zn(OH) 2 + 2NaOH (excess) --- Na2ZnO2 + 2H20