Question

(a) How is lead sulphate prepared in the aboratory?

(b) Why lead sulphate cannot be prepared by the action of dilute H₂SO₄ on lead oxide?

Answer 1

(a) Lead sulphate is prepared from insoluble lead oxide, by first converting lead oxide into soluble lead nitrate with dilute nitric acid and then treating the resulting solution with sulphuric acid to obtain white ppt. of Lead sulphate.

PbO + 2HNO₃ ⟶ Pb(NO₃)₂ + H₂O

Pb(NO₃)₂ + H₂SO₄ ⟶ PbSO₄ + 2HNO₃

(b) Lead sulfate is insoluble, when lead is added to sulfuric acid it only reacts on the surface. The lead becomes coated with insoluble lead sulfate and the lead in the interior can't react. Therefore lead sulfate cannot be prepared by adding dilute sulfuric acid.