Question

How will the addition of sodium acetate to an acetic acid solution affect the pH?

A. solution becomes hotter
B. It will lower the pH
C. It will raise the pH
D. pH will not change
E. pH cannot be measured

I selected answer D and got it wrong. I don't understand why...

Answer 1

Sodium acetate/acetic acid is a buffer solution. The pH of 0.1M acetic acid is about 2.9. If you have 0.1M acetic acid with 0.1M sodium acetate, the pH is about 4.7. I expect the answer is C. Another way to look at it is that you are adding a base to an acid so the pH should become more basic; i.e., the pH will increase.