Problem: A buffer that contains 0.13 M of an acid, HA and 0.33 M of its conjugate base A-, has a pH of 4.27. What is the pH after 0.012 mol of NaOH are added to 0.73 L of the solution?

FREE Expert Solution

We are asked to calculate the pH of the buffer after 0.012 mol of NaOH is added.

The buffer solution is composed of HA and A-.


HA is a weak acid and based on the Bronsted-Lowry definition, an acid is a proton (H+). Once A- loses its proton, its conjugate base is formed:

HA(aq)  +   H­2O(l)  →   A(aq)   +   H3O+(aq)
(weak acid)    (base)     (conjugate base)    (conjugate acid)

Whenever we have a conjugate base and a weak acid, we have a buffer.


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Problem Details

A buffer that contains 0.13 M of an acid, HA and 0.33 M of its conjugate base A-, has a pH of 4.27. What is the pH after 0.012 mol of NaOH are added to 0.73 L of the solution?