# How do you calculate the molarities of CH_3COOH and CH_3COO^- in buffer solution?

$p H = p {K}_{a} + {\log}_{10} \left\{\frac{\left[A c {O}^{-}\right]}{\left[H O A c\right]}\right\}$
Well, you need starting concentrations of acetic acid and acetate, and also the $p {K}_{a}$ of $\text{acetic acid}$, which is $4.76$. See here for the derivation of this formula.