Write the equilibrium constant expression for this reaction:2H+(aq)+CO2−3(aq) → H2CO3(aq)

Equilibrium Constant Expression for the Given Reaction

1. Identify the Reaction
   The chemical reaction is:
   $2 \text{H}^+(aq) + \text{CO}_3^{2-}(aq) \rightarrow \text{H}_2\text{CO}_3(aq)$

2. Write the Expression
   The equilibrium constant expression $K$ is formulated by taking the concentrations of the products raised to the power of their coefficients and dividing by the concentrations of the reactants raised to the power of their coefficients.

3. Apply the Formula
   For the reaction, the expression for the equilibrium constant $K$ can be given as follows:
   $K = \frac{[\text{H}_2\text{CO}_3]}{[\text{H}^+]^2[\text{CO}_3^{2-}]}$

4. Summary
   In this expression, $[\text{H}_2\text{CO}_3]$ represents the molar concentration of carbonic acid at equilibrium, while $[\text{H}^+]$ and $[\text{CO}_3^{2-}]$ are the molar concentrations of hydrogen ions and carbonate ions, respectively, at equilibrium raised to their respective coefficients.

Final Answer

The equilibrium constant expression is: $K = \frac{[\text{H}_2\text{CO}_3]}{[\text{H}^+]^2[\text{CO}_3^{2-}]}$