a $50$mL sample of $0\mathrm{.}12$M butanoic acid is titrated with a $0\mathrm{.}12$M NaOH solution. The Ka of butanoic acid is $1\mathrm{.}5$ x $10^-5.$ Calculate the pH at each of the following points: A$.)$ Before any NaOH is added B$.)$ After the addition of $20\mathrm{.}5$mL of NaOH C$.)$ At the equivalence point