(a) Show how \(\mathrm{HCO}_{3}^{-}\) can act as a weak acid. (b) Show how \(\mathrm{HCO}_{3}^{-}\) can act as a weak base. (c) Since \(\mathrm{HCO}_{3}^{-}\) can act as either an acid or a base, can it be its own conjugate?

(a) As a weak acid, HCO3- donates a proton to a water molecule, forming H2CO3 and OH-. The reaction is: \[ \mathrm{HCO}_{3}^{-} + \mathrm{H}_{2} \mathrm{O} \rightleftharpoons \mathrm{H}_{2} \mathrm{CO}_{3} + \mathrm{OH}^{-} \]. (b) As a weak base, HCO3- accepts a proton from a water molecule, forming CO3^2- and H3O+. The reaction is: \[ \mathrm{HCO}_{3}^{-} + \mathrm{H}_{2} \mathrm{O} \rightleftharpoons \mathrm{CO}_{3}^{2-} + \mathrm{H}_{3}\mathrm{O}^{+} \]. (c) HCO3- cannot be its own conjugate acid or base, as it forms different species (CO3^2- and H2CO3) when it acts as a base and as an acid, respectively. However, it is an amphiprotic species, since it can both donate and accept protons in different reactions.