Problem: Compute the equilibrium constant for the spontaneous reaction between Ni2+(aq) and Cd(s).

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FREE Expert Solution

We are asked to find the equilibrium constant K for the spontaneous reaction between Ni2+(aq) and Cd(s).


We will use the Gibbs Free Energy Equation to calculate the equilibrium constant. The Gibbs Free relates the potential of compounds and cell equilibrium:


In a Galvanic Cell, the Gibbs free energy is related to the potential by:

Go = -nFEcello 

     If the Eocell > 0, then the process is spontaneous (galvanic cell)

     If the Eocell < 0, then the process is nonspontaneous (electrolytic cell)


ΔGo can also be expressed by the equilibrium constant Keq of the reaction.

Go = RT ln Keq 


Combining the two equations since both are equal to ΔGo gives:

-nFEcello = RT ln Keq 

where

n = # of e- transferred
F = Faraday’s constant = 96485 J/(mol e-)
cell = standard cell potential, V

R = gas constant, 8.314 J/mol e-  K

T = temperature in K

Keq = equilibrium constant of the reaction


In the Gibbs Equation, we have to determine the E°cell first, as well as the anode (oxidation) and the cathode (reduction) in the concentration cell and the number of electrons transferred (n).

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Problem Details

Compute the equilibrium constant for the spontaneous reaction between Ni2+(aq) and Cd(s).