The $\mathrm{p}{K}_{\mathrm{a}}^{\circ }$ of a weak acid, HA, is 4.80. The $\mathrm{p}{K}_{\mathrm{b}}^{\circ }$, of a weak base, BOH, is 4.78. The pH of an aqueous solution of the corresponding salt, BA, will be

For the salt formed from a weak acid and a weak base, the pH of the solution is given by $\mathrm{pH}=\frac{1}{2}\left(\mathrm{p}{K}_{\mathrm{w}}^{\circ }+\mathrm{p}{K}_{\mathrm{a}}^{\circ }-\mathrm{p}{K}_{\mathrm{b}}^{\circ }\right)$

Hence, at 25 ° C, we will have $\mathrm{pH}=\frac{1}{2}(14+4.80-4.78)=7.01$