A student is attempting to design an electrochemical cell that spontaneously operates when created. They are given a set of unknown chemicals and a list of their reduction potentials as shown below:

Question

A student is attempting to design an electrochemical cell that spontaneously operates when created. They are given a set of unknown chemicals and a list of their reduction potentials as shown below:

 

Half-Reaction (Standard Reduction Potentials)	E°
A+ + e- → A	-0.29 V
B + 2e- → B2-	0.56 V
C + e- → C-	1.25 V

 

What would be the maximum cell potential they could create given the information above?

Answer 1

The standard cell potential is given by subtracting the reduction potential of the half reaction at the anode (oxidation) from the standard reduction potential at the cathode (reduction). In order to be spontaneous, the cell potential must be positive.

The maximum standard positive cell potential would be achieved by having the A reaction at the anode and the C reaction at the cathode. The cell potential would then be 1.25 V - (-0.29)V = 1.54 V