Question

Give a reason to support that sulphuric acid is a dehydrating agent.

Answer 1

Sulphuric acid is highly soluble in water and has a strong affinity towards the water and hence it can be used as a dehydrating agent.

When dissolved in water it forms mono (H₂SO₄.H₂O) and di (H₂SO₄.2H₂O) hydrates and the reaction is exothermic.

The dehydration property can also be illustrated by its reaction with organic compounds such as sugar, oxalic acid and formic acid.

\[\ce{\underset{\text{(Sucrose)}}{C12H22O11} + H2SO4 -> 12C + H2SO4.11H2O}\]

\[\ce{\underset{\text{(Formic acide)}}{HCOOH} + H2SO4 -> CO + H2SO4.H2O}\]

\[\ce{\underset{\text{(Oxalic acid)}}{(COOH)2} + H2SO4 -> CO + CO2 + H2SO4.H2O}\]