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Equilibrium Constant in Half-Reactions

What is the Ecell and the equilibrium constant, Kc, for the cell represented by the combination of the following half-reactions?

2 Hg2+(aq) + 2e- equilibrium Hg2 2+(aq) E= 0.92V
Cr3+(aq) + 3e- equilibrium Cr(s) E= -0.74 V

Solution Preview

2 Hg2+(aq) + 2e- <-----> Hg2 2+(aq) E= 0.92V
Cr3+(aq) + 3e- <-----> Cr(s) E= -0.74 V

First, we have to write the equations so that the electrons balance. Since the first reaction involves 2 electrons while the second reaction involves 3 electrons, we can figure out that 6 electrons will be involved in the total reaction. So, we multiply the first reaction by 3 and we multiply the second reaction by 2.


6 Hg2+(aq) + 6e- <-----> 3 Hg2 2+(aq) ...

Solution Summary

This solution shows step-by-step explanations to determine the Ecell and the equilibrium constant. All formulas used are shown.