Question

Question #399f7

Answer 1

Add more acetic acid (HOAc)

Explanation:

Adding acid into an aqueous solution functions to deliver hydronium ions `(H_3O^+)` into the solution. If ions of Calcium and Carbonate are present, Hydrogen ions `(H^+)` from the `H_3O^+` will coordinate (bond) with the carbonate ion `(CO_3^(2-))` forming the weak acid 'Hydrogen Carbonate' `((H-CO_3)^-)`.

Hydrogen Carbonate is no longer part of the Calcium Carbonate Equilibrium which is now deficient in carbonate ions on the product side of the equilibrium.

`CaCO_3` `rightleftharpoons Ca^(2+) + CO_3^(2-)` => `CaCO_3 => Ca^(2+) + (_)`

Additional unionized Calcium Carbonate then ionizes in order to replace the `CO_3^(2-)` that combined with `H^+` from the acetic acid.

This is typically described by saying "the equilibrium
`CaCO_3` `rightleftharpoons Ca^(2+) + CO_3^(2-)` shifts to the right increasing solubility of the `CaCO_3`".