Question #44262

Consider the standard electrode potentials $E^\circ(M^{2+}/M)$ and $E^\circ(M^{3+}/M^{2+})$ of the 3d transition metals at $298\text{ K}$, along with their thermodynamic parameters. Which of the following statements are CORRECT?

I. The $E^\circ(M^{2+}/M)$ value of \ce{Mn} ($-1.18\text{ V}$) is more negative than that of \ce{Cr} ($-0.90\text{ V}$) because both the sublimation enthalpy and the sum of the first two ionization enthalpies $(IE_1 + IE_2)$ are lower for \ce{Mn} than for \ce{Cr}$. II. The$E^\circ(M^{2+}/M)$value of \ce{Ni} ($-0.25\text{ V}$) is more negative than expected from the general trend primarily due to the exceptionally high negative hydration enthalpy of \ce{Ni^{2+}_{(aq)}}, which compensates for its high$(IE_1 + IE_2)$. III. The$E^\circ(M^{2+}/M)$value of \ce{Zn} ($-0.76\text{ V}$) is more negative than that of \ce{Cu} ($+0.34\text{ V}$) primarily because the hydration enthalpy of \ce{Zn^{2+}_{(aq)}}$ is significantly more negative than that of \ce{Cu^{2+}_{(aq)}}$. IV. The$E^\circ(M^{3+}/M^{2+})$value for \ce{Mn} ($+1.57\text{ V}$) is highly positive compared to \ce{Fe} ($+0.77\text{ V}$) because the removal of the third electron from \ce{Mn^{2+}} requires overcoming a large loss in exchange energy compared to \ce{Fe^{2+}}$.