Final answer:
The ionization of nitrous acid (HNO2) in water is represented by the equation HNO2 ⇌ H+ + NO2-.
Step-by-step explanation:
The chemical equation for the ionization of nitrous acid (HNO₂) in water is:
HNO₂ ↔ H⁺ + NO₂⁻
This represents the first step in the ionization process of HNO₂, a weak acid, where it partially dissociates to form protons (H⁺) and nitrite ions (NO₂⁻) in a reversible reaction.