50 mL of 0.1 M acetic acid is mixed with 50 mL of 0.1 M sodium acetate (the conjugate base). The Ka of acetic acid is approximately 1. 74 X 10 -5. What is the pH of the resulting solution?

4.76

Explanation:

In this case, we have to start with the buffer system:

We have an acid () and a base (). Therefore we can write the henderson-hasselbach reaction:

If we want to calculate the pH, we have to calculate the pKa:

According to the problem, we have the same concentration for the acid and the base 0.1M. Therefore:

If we divide:

If we do the Log of 1:

So:

With this in mind, the pH is 4.76.

I hope it helps!