Question

 Name the substance used for drying ammonia gas? Why cannot substances such as conc.H₂SO₄, anhydrous calcium chloride and phosphorus pentoxide be used for drying ammonia gas?

Answer 1

The substance used for drying ammonia gas is quicklime( calcium
oxide) .Concentrated sulphuric acid, anhydrous calcium chloride and phosphorus pentoxide cannot be used for drying ammonia gas because ammonia being basic reacts wi th them, and the following reaction takes place

Conc.H₂SO₄ reacts with ammonia to form ammonium sulphate.

2 NH₃ + H₂SO₄(conc..) → (NH₄)₂SO₄

Phosphorus pentoxide reacts with ammonia to form ammonium phosphate.

6 Nh₃ + P₂O₅ + 3H₂O →  2(NH₄)₃PO₄

Anhydrous calcium chloride combines with ammonia to form addi tion compound.

4 NH₃ + CaCI₂ → CaCI₂. 4NH₃