Question

What does it mean for a weak acid to be in equilibrium?

Answer 1

A) The acids only slightly dissociate and readily undergo reverse reaction.

for example:

acetic acid
CH₃COOH(aq) ⇄ CH₃COO⁻(aq) + H⁺(aq)

nitrous acid
HNO₂(aq) ⇄ H⁺(aq) + NO₂⁻(aq)

carbonic acid
H₂CO₃(aq) ⇄ H⁺(aq) + HCO₃⁻(aq)
HCO₃⁻(aq) ⇄ H⁺(aq) + CO₃²⁻(aq)