Write the dissociation reaction and the corresponding \(K_{\mathrm{a}}\) equilibrium expression for each of the following acids in water. a. HCN b. \(\mathrm{HOC}_{6} \mathrm{H}_{5}\) c. \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{3}{ }^{+}\)

a. Dissociation reaction of HCN: \[ \mathrm{HCN} \rightleftharpoons \mathrm{H}^+ + \mathrm{CN}^{-} \] \(K_a\) expression for HCN: \[ K_a = \frac{[\mathrm{H}^+] [\mathrm{CN}^{-}]} {[\mathrm{HCN}]} \] b. Dissociation reaction of \(\mathrm{HOC}_{6} \mathrm{H}_{5}\): \[ \mathrm{HOC}_{6} \mathrm{H}_{5} \rightleftharpoons \mathrm{H}^+ + \mathrm{OC}_{6} \mathrm{H}_{5}^{-} \] \(K_a\) expression for \(\mathrm{HOC}_{6} \mathrm{H}_{5}\): \[ K_a = \frac{[\mathrm{H}^+] [\mathrm{OC}_{6} \mathrm{H}_{5}^{-}]} {[\mathrm{HOC}_{6} \mathrm{H}_{5}]} \] c. Dissociation reaction of \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{3}{ }^{+}\): \[ \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{3}{ }^{+} \rightleftharpoons \mathrm{H}^+ + \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2} \] \(K_a\) expression for \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{3}{ }^{+}\): \[ K_a = \frac{[\mathrm{H}^+] [\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2}]} {[\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{3}{ }^{+}]} \]