The standard reduction potentials at for several half-cells are given: ; ; ; . Which is the stronges — Electrochemistry Chemistry Question
Question
The standard reduction potentials at $298\text{ K}$ for several half-cells are given: $Zn^{2+}(aq) + 2e^- \rightleftharpoons Zn(s), E^\circ = -0.762\text{ V}$; $Cr^{3+}(aq) + 3e^- \rightleftharpoons Cr(s), E^\circ = -0.740\text{ V}$; $2H^+(aq) + 2e^- \rightleftharpoons H_2(g), E^\circ = 0.000\text{ V}$; $Fe^{3+}(aq) + e^- \rightleftharpoons Fe^{2+}(aq), E^\circ = +0.770\text{ V}$. Which is the strongest reducing agent among the species listed?
💡 Solution & Explanation
The strongest reducing agent is the species that is most readily oxidized. This corresponds to the half-reaction with the lowest (most negative) standard reduction potential. Since the $Zn^{2+}/Zn$ couple has the most negative $E^\circ$ ($-0.762\text{ V}$), metallic $Zn(s)$ exhibits the greatest tendency to lose electrons.