How to calculate the pH of an acetic acid/ calcium acetate buffer?
In general: $\ce{acid + H2O &lt;=&gt; base + H_3O^+}$
It is called the Henderson-Hasselbalch equation 
$\ce{pH} = \mathrm{p}K_\mathrm{a} + \log\frac{\ce{[base]}}{\ce{[acid]}}$
I believe the equilibrium constant for a such a neutralisation would look like $K_n = K_\mathrm{a}K_\mathrm{b}\frac{1}{K_\mathrm{w}}$