Question

Give reason for the following fact:

H₂SO₄ is a diprotic acid.

Answer 1

H₂SO₄ is a diprotic acid because:

1. It contains two hydrogen atoms that can dissociate as protons (H⁺).
2. It reacts in two steps with bases. First forming hydrogen sulphate (HSO⁴⁻), then sulphate \[\ce{(SO^{2−}_4)}\].
3. This ability to donate two protons (H⁺) makes it dibasic or diprotic.
4. Example:
   \[\ce{H2SO4 + NaOH -> NaHSO4 + H2O}\]
   \[\ce{NaHSO4 + NaOH -> Na2SO4 + H2O}\]

Thus, H₂SO₄ can release two H⁺ ions in acid-base reactions.