Write the chemical equation and the \(K_{b}\) expression for the reaction of each of the following bases with water: (a) propylamine, $\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{NH}_{2} ;$ (b) monohydrogen phosphate ion, \(\mathrm{HPO}_{4}^{2-} ;(\mathbf{c})\) benzoate ion, $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CO}_{2}^{-}$

(a) Chemical equation for propylamine with water: \[\mathrm{C}_{3}\mathrm{H}_{7}\mathrm{NH}_{2} + \mathrm{H}_{2}\mathrm{O} \rightleftharpoons \mathrm{C}_{3}\mathrm{H}_{7}\mathrm{NH}_{3}^{+} + \mathrm{OH}^{-}\] \(K_{b}\) expression for propylamine: \[K_{b} = \frac{[\mathrm{C}_{3}\mathrm{H}_{7}\mathrm{NH}_{3}^{+}][\mathrm{OH}^{-}]}{[\mathrm{C}_{3}\mathrm{H}_{7}\mathrm{NH}_{2}]} \] (b) Chemical equation for monohydrogen phosphate ion with water: \[\mathrm{HPO}_{4}^{2-} + \mathrm{H}_{2}\mathrm{O} \rightleftharpoons \mathrm{H}_{2}\mathrm{PO}_{4}^{-} + \mathrm{OH}^{-}\] \(K_{b}\) expression for monohydrogen phosphate ion: \[K_{b} = \frac{[\mathrm{H}_{2}\mathrm{PO}_{4}^{-}][\mathrm{OH}^{-}]}{[\mathrm{HPO}_{4}^{2-}]} \] (c) Chemical equation for benzoate ion with water: \[\mathrm{C}_{6}\mathrm{H}_{5}\mathrm{CO}_{2}^{-} + \mathrm{H}_{2}\mathrm{O} \rightleftharpoons \mathrm{C}_{6}\mathrm{H}_{5}\mathrm{CO}_{2}\mathrm{H} + \mathrm{OH}^{-}\] \(K_{b}\) expression for benzoate ion: \[K_{b} = \frac{[\mathrm{C}_{6}\mathrm{H}_{5}\mathrm{CO}_{2}\mathrm{H}][\mathrm{OH}^{-}]}{[\mathrm{C}_{6}\mathrm{H}_{5}\mathrm{CO}_{2}^{-}]} \]