In the reaction , which species functions as the Lewis acid? — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

According to Lewis theory, an acid is an electron-pair acceptor and a base is an electron-pair donor. In this reaction, the iodide ion ($I^-$) donates an electron pair (acting as a Lewis base), and the $I_2$ molecule accepts the electron pair into an empty antibonding orbital to form $I_3^-$, thus acting as the Lewis acid.