Based on the information in the table of standard reduction potentials below, what is the standard cell potential for an electrochemical cell that has iron, Fe, and magnesium, Mg, electrodes? Also, identify the cathode. Standard Reduction Potentials (volts) in Aqueous
Solution
$\begin{array} { l l } \mathrm { Pb } ^ { 4 + } + 2 \mathrm { e } ^ { - } \rightarrow \mathrm { Pb } ^ { 2 + } & + 1.80 \ \mathrm { Au } ^ { 3 + } + 3 \mathrm { e } ^ { - } \rightarrow \mathrm { Au } & + 1.50 \ \mathrm { Fe } ^ { 3 + } + 3 \mathrm { e } ^ { - } \rightarrow \mathrm { Fe } & + 0.771 \ \mathrm { I } _ { 2 } + 2 \mathrm { e } ^ { - } \rightarrow 2 \mathrm { I } ^ { - } & + 0.535 \ \mathrm {~Pb} ^ { 2 + } + 2 \mathrm { e } ^ { - } \rightarrow \mathrm { Pb } & - 0.124 \ \mathrm { Al } ^ { 3 + } + 3 \mathrm { e } ^ { - } \rightarrow \mathrm { Al } & - 1.66 \ \mathrm { Mg } ^ { 2 + } + 2 \mathrm { e } ^ { - } \rightarrow \mathrm { Mg } & - 2.37 \ \mathrm {~K} ^ { + } + \mathrm { e } ^ { - } \rightarrow \mathrm { K } & - 2.93 \end{array}$

Question

Quizplus · Accepted Answer

The standard cell potential is the difference between the standard reduction potentials of the two half-cells. The half-cell with the more positive reduction potential is the cathode. In this case, the standard reduction potential of Fe is +0.771 V and the standard reduction potential of Mg is -2.37 V. Therefore, the standard cell potential is +0.771 V - (-2.37 V) = +3.14 V. The cathode is the electrode where reduction occurs, which is the electrode with the more positive reduction potential. Therefore, the cathode is the Fe electrode.

Based on the Information in the Table of Standard Reduction