Question

Carbonic acid (H2CO3) is a polyprotic acid. Write balanced chemical equations for the sequence of reactions that carbonic acid can undergo when it's dissolved in water.

Answer 1

H₂CO₃(aq) ⇄ H⁺(aq) + HCO₃⁻(aq)

HCO₃⁻(aq) ⇄ H⁺(aq) + CO₃²⁻(aq)

Step-by-step explanation:

Carbonic acid (H₂CO₃) has 2 acidic protons. When is dissolved in water, it loses the protons (H⁺) in two sequential steps:

- First, it loses 1 proton to form the hydrogen carbonate ion (HCO₃⁻)

H₂CO₃(aq) ⇄ H⁺(aq) + HCO₃⁻(aq)

- Then, the acid carbonate anion loses its proton to form carbonate ion (CO₃²⁻):

HCO₃⁻(aq) ⇄ H⁺(aq) + CO₃²⁻(aq)