Question

Zinc sulphate is called a “salt”, sulphur dioxide an “acidic oxide” and lead monoxide a “basic oxide”. What is meant by these terms ?

Answer 1

(i) Zinc sulphate is a salt, because it is formed by the complete replacement of the hydrogen of sulphuric acid by zinc.

Zn + H₂SO₄ → ZnSO₄ (Zinc sulphate) + H₂

(ii) Sulphur dioxide is an acidic oxide, because it is an oxide of non-metal, which dissolves in water to form an   acid known as sulphurous acid. It reacts with a base to form salt and water.

SO₂ + H₂O → H₂SO₃ (Sulphurous acid) 

SO₂ + 2NaOH → Na₂SO₃ (Sodium sulphite) + H₂O

(iii) Lead monoxide is a basic oxide, because it is a metallic oxide and it reacts with an acid to form salt and water only.

PbO + 2HCl → PbCl₂ (Lead chloride) + H₂O