Cell Potential Question

Question

Calculate the Eocell for the redox reaction shown below in volts:

3K(s)+Cr+3(aq)→3K+1(aq)+Cr(s)

Answer 1

In the reaction as written, we see that K(s) is being oxidized to K+ and Cr3+ is being reduced to Cr(s).

In a galvanic cell, this makes K the anode and Cr the cathode. To find Eº_cell we take the standard reduction potential at the cathode and subtract the standard reduction potential at the anode.

From a table of standard reduction potentials, I find the following values:

K+ ... -2.92 V

Cr3+ ... -0.74

-0.74 - (-2.92) = +2.18 V = Eº_cell