Chapter 13, Problem 13.18PAE

Four voltaic cells are set up. In each, one half-cell contains a standard hydrogen electrode. The second half-cell is one of the following: ${\text{Cr}}^{\text{3+}}\left(\text{aq,}\text{1}\text{.0}\text{M}\right)|\text{Cr}\left(\text{s}\right),{\text{Fe}}^{\text{2+}}\left(\text{aq,}\text{1}\text{.0}\text{M}\right)|\text{Fe}\left(\text{s}\right)\text{,}{\text{Cu}}^{\text{2+}}\left(\text{aq,}\text{1}\text{.0}\text{M}\right)|\text{Cu}\left(\text{s}\right)$ , or ${\text{Mg}}^{\text{2+}}\left(\text{aq,}\text{1}\text{.0}\text{M}\right)|\text{Mg}\left(\text{s}\right)$ .

(a) In which of the voltaic cells does the hydrogen electrode serve as the cathode?

(b) Which voltaic cell produces the highest voltage? Which produces the lowest voltage?