Question

Why is Concentrated Sulphuric acid not used as a drying agent to dry Hydrogen gas?

Answer 1

A gas can be dried using sulphuric acid if the gas has no chemical action with acid or it does react with sulphuric acid.
Hydrogen sulphide gas cannot be dried using sulphuric acid as H2S gas is oxidised by sulphuric acid to Sulphur. Therefore, the H2S gas has chemical action with acid and hence it reacts with it , therefore, cannot be dried using it.
H2SO4 + H2S -------> 2H2O + SO2 + S