Explanations:- The given buffer solution has acetic acid(a weak acid) and it's conjugate base(acetate ion).
When an acid is added to a buffer solution then it reacts with the base present in the buffer and if a base is added then it reacts with the acid present in the buffer.
The question asks to write the reaction to show the buffer capacity when a base is added to the solution.
As discussed above, the added base will react with the acid present in the buffer solution. The acid present in the buffer solution is acetic acid, so the added base will react with acetic acid and will form the acetate ion and water so that the added base could be neutralized.
The reaction is shown below:
[tex]CH_3COOH(aq)+OH^-(aq)\rightleftharpoons CH_3COO^-(aq)+H_2O(l)[/tex]
