Write a net ionic equation to show that nitrous acid behaves as a brønsted-lowry acid in water.

Balanced chemical reaction: HNO₂ (aq) + H₂O (l) ⇄ NO₂⁻ (aq) + H₃O⁺ (aq).

According to Bronsted-Lowry theory acid are donor of protons and bases are acceptors of protons (the hydrogen cation or H⁺).

Nitrous acid is weak Bronsted acid and it can lose proton and become conjugate base NO₂⁻ and water is Bronsted base.