Sodium hydroxide as a buffer in solution

Strong bases act as buffers in solution at high pH values (above 12). Similarly, strong acids act as buffers in solution at pH below 2. Let's say that we have 100 ml of 0.1 M solution of sodium hydroxide (NaOH) and titrate that with 0.1 M hydrochloric acid (HCl). The initial pH of the NaOH solution can be calculated using the following equation:

                                                                     pH = 14+log (0.1) = 13

 The following table shows the change in pH after addition of each increment of the acid:

As seen in the table, after addition of 50 ml of the acid the pH changes from 13 to 12.52 (0.48 change).  Even after adding 80 ml the pH changes to 12.05 (0.95 change). Thus, strong bases in solution act as buffers at high pH values.

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