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Standard potentials are measured against the standard hydrogen electrode (S.H.E.

ID: 958251 • Letter: S

Question

Standard potentials are measured against the standard hydrogen electrode (S.H.E.). Because it is not always convenient to use a S.H.E., often other reference electrodes are used. The saturated calomel electrode (S.C.E.) is one commonly used reference electrode, with a potential of 0.242 V versus the S.H.E. Using a table of standard reductions, determine what the potential of each reduction below would be versus the S.C.E.

Standard potentials are measured against the standard hydrogen electrode (S.H.E.). Because it is not always convenient to use a S.H.E., often other reference electrodes are used. The saturated calomel electrode (S.C.E.) is one commonly used reference electrode, with a potential of +0.242 V versus the S.H.E. Using a table of standard reductions, determine what the potential of each reduction below would be versus the S.C.E Number a) Cu2+(aq)+2e- Cu(s E= Number b) Ni2+(aq) +2e Ni(s) =11-0.492 | V

Explanation / Answer

Calculation of cell potential

a) E = Eo - 0.242

For the reaction, Eo = 0.337 V

So, E = 0.337 - 0.242 = 0.095 V

b) E = Eo - 0.242

For the reaction, Eo = -0.25 V

So, E = -0.25 - 0.242 = -0.492 V