Chemical and Ionic Equilibrium 1 Question 14
15. The species present in solution when $\mathrm{CO}_{2}$ is dissolved in water are
(2006 Main)
(a) $\mathrm{CO}{2}, \mathrm{H}{2} \mathrm{CO}{3}, \mathrm{HCO}{3}^{-}, \mathrm{CO}_{3}^{2-}$
(b) $\mathrm{H}{2} \mathrm{CO}{3}, \mathrm{CO}_{3}^{2-}$
(c) $\mathrm{HCO}{3}^{-}, \mathrm{CO}{3}^{2-}$
(d) $\mathrm{CO}{2}, \mathrm{H}{2} \mathrm{CO}_{3}$
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Solution:
- When $\mathrm{CO}_{2}$ is dissolved in water, following equilibria are established:
$$ \begin{aligned} \mathrm{H}{2} \mathrm{O}+\mathrm{CO}{2} & \rightleftharpoons \mathrm{H}{2} \mathrm{CO}{3} \ \mathrm{H}{2} \mathrm{CO}{3} & \rightleftharpoons \mathrm{H}^{+}+\mathrm{HCO}{3}^{-} \ \mathrm{HCO}{3}^{-} & \rightleftharpoons \mathrm{H}^{+}+\mathrm{CO}_{3}^{2-} \end{aligned} $$
Therefore, in solution, all of the above mentioned species exist.
