Final answer:
Added acid in a formic acid and sodium formate buffer solution will react with the formate ion (CHO₂−), which acts as a weak base, to form formic acid and water, thereby maintaining the pH of the buffer solution.
Step-by-step explanation:
When an acid is added to a buffer solution made from formic acid (HCHO₂) and sodium formate (NaCHO₂), the added acid will react with the formate ion (CHO₂−). Formate functions like a weak base in this context. The strong acid, such as hydrochloric acid (HCl), will react completely with formate to yield formic acid and water, maintaining the buffer's pH.
A buffer solution consists typically of a weak acid and its conjugate base or a weak base and its conjugate acid. When an excess of protons (H+) from added strong acid is present, they are consumed by the conjugate base (formate ions in this case), preventing significant pH changes.