pOH = pKb + log This passes the above test because increasing the amount of acid [HA] should
always increase the pOH of any solution.
Example: Given the Ka(Acetic acid) = 1.8 × 10−5, what is the pH of a solution of
0.1 M acetic acid and 0.01 M sodium acetate?Solution: First, write the balanced chemical equation that establishes the
equilibrium.
HC 2 H 3 O 2 (aq) H+(aq) + C 2 H 3 O 2 −(aq)The Na+ ion is merely a spectator ion that has no effect on the pH of the solution,
and thus is not a part of the ensuing calculations.
Second, write the relevant version of theHenderson-Hasselbalch equation.pH = pKa(Acetic acid) + log Third, covert the Ka to pKa, and write the algebraic
expression.