The species present in solution when is dissolved in water — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

When $\text{CO}_2$ dissolves in water, it forms an equilibrium with $\text{H}_2\text{CO}_3$. Carbonic acid is a weak diprotic acid, so it sequentially dissociates to establish equilibria with $\text{HCO}_3^-$ and $\text{CO}_3^{2-}$. Therefore, all these species ($\text{CO}_2$, $\text{H}_2\text{CO}_3$, $\text{HCO}_3^-$, and $\text{CO}_3^{2-}$) are present in the solution simultaneously.