The equilibrium constant, K, for a redox reaction is related to the standard potential, E∘, by the equation

lnK=nFE∘RT

where n is the number of moles of electrons transferred, F (the Faraday constant) is equal to 96,500 C/(mol e−) , R (the gas constant) is equal to 8.314 J/(mol⋅K) , and T is the Kelvin temperature.

Standard reduction potentials

Reduction half-reaction E∘ (V)
Ag+(aq)+e−→Ag(s) 0.80
Cu2+(aq)+2e−→Cu(s) 0.34
Sn4+(aq)+4e−→Sn(s) 0.15
2H+(aq)+2e−→H2(g) 0
Ni2+(aq)+2e−→Ni(s) −0.26
Fe2+(aq)+2e−→Fe(s) −0.45
Zn2+(aq)+2e−→Zn(s) −0.76
Al3+(aq)+3e−→Al(s) −1.66
Mg2+(aq)+2e−→Mg(s) −2.37
Part A

Use the table of standard reduction potentials given above to calculate the equilibrium constant at standard temperature (25 ∘C) for the following reaction:

Fe(s)+Ni2+(aq)→Fe2+(aq)+Ni(s)

Express your answer numerically.

K =
Part B

Calculate the standard cell potential (E∘) for the reaction

X(s)+Y+(aq)→X+(aq)+Y(s)

if K = 4.88×10−3.

Express your answer to three significant figures and include the appropriate units.

E∘ =