Which of the following could be added to buffer the sol of sodium acetate? a) hydrochloric acid a) sodium chloride or potassium acetate c) acetic acid or hydrochloric acid d) potassium acetate only

c) Acetic acid or hydrochloric acid

A buffer consists of a weak acid and its conjugate base. Acetate ion is the conjugate base of acetic acid. So, add acetic acid to sodium acetate and you have a buffer.

Adding HCl is also correct. HCl reacts completely with sodium acetate,

HCl + NaC_2H_3O_2 → NaCl + HC_2H_3O_2

If you add enough HCl to neutralize about half the sodium acetate, you will again have an acetate buffer.

“a) Hydrochloric acid” is also correct. However, if the examiners allow only a single choice, pick “c)”.

“b) Sodium chloride or potassium acetate” is incorrect. Neither compound provides acetic acid to make a buffer.

“d) Potassium acetate only” is incorrect for the same reason.