What is the pH of an acetic acid solution where the concentration of acetic acid is 2 mM and the concentration of sodium acetate is 20 mM. The pKa of acetic acid is 4.76.

pH = 5.76

Explanation:

We can solve this problem by using Henderson-Hasselbach's equation:

pH = pKa + log

We are already know all the required information, thus we input the data given by the problem:

pH = 4.76 + log(20/2)

And finally calculate the pH:

pH = 5.76

The pH of that acetic acid solution is 5.76.