The pKa of acetic acid is 4.76. Substitution in equation (3.83) gives

The molar ratio of [salt]/[acid] is 2.754. Since 100 cm3 of 0.1 mol dm 3 acetic acid contains 0.01 mol, we would require 0.027 54 mol of sodium acetate (2.258 g), ignoring dilution effects.

Equations (3.83) and (3.84) are also useful in calculating the change in pH which results from the addition of a specific amount of acid or alkali to a given buffer solution, as seen from the following calculation in Example 3.10.

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