Question

What happens when potassium nitrate is heated with concentrated H₂SO₄ below 200°C? Explain using chemical equations.

Answer 1

When potassium nitrate (KNO₃) is heated with concentrated sulphuric acid below 200°C, potassium hydrogen sulphate and nitric acid are formed.

\[\ce{KNO3 ​+ H2​SO4​ -> KHSO4 ​+ HNO3​}\]

The nitric acid (HNO₃) formed is volatile and distils off.