Which of the following species are amphiprotic (can act as both proton donors and proton acceptors) — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

Amphiprotic species must possess at least one ionizable proton to donate and a site to accept a proton. $H_2PO_4^-$ can become $HPO_4^{2-}$ or $H_3PO_4$. $HCO_3^-$ can become $CO_3^{2-}$ or $H_2CO_3$. $HS^-$ can become $S^{2-}$ or $H_2S$. However, $H_3O^+$ is only a proton donor in water and cannot realistically accept another proton.