Consider the following reduction processes:
\( \mathrm{Al^{3+}} + 3e^- \rightarrow \mathrm{Al(s)}, \ E^\circ = -1.66 \, \text{V} \)
\( \mathrm{Fe^{3+}} + e^- \rightarrow \mathrm{Fe^{2+}}, \ E^\circ = +0.77 \, \text{V} \)
\( \mathrm{Co^{3+}} + e^- \rightarrow \mathrm{Co^{2+}}, \ E^\circ = +1.81 \, \text{V} \)
\( \mathrm{Cr^{3+}} + 3e^- \rightarrow \mathrm{Cr(s)}, \ E^\circ = -0.74 \, \text{V} \)
The tendency to act as reducing agent decreases in the order:
