Class 12 Chemistry Electrochemistry Electrochemical Cell

Electrochemical Cell and Gibbs Energy of the Reaction

  • Electrical work done (1 second) = Electrical potentialX Total charge passed
  • Passing the charges reversibly through the galvanic cell results in maximum work.
  • Reversible work done by galvanic cell = Decrease in Gibbs energy
  • Let E = Emf of the cell

           nF = Amount of charge passed

        ΔrG = Gibbs energy of the reaction

        ΔrG = -nFEcell

  For the reaction,

           Zn(s) + Cu2+ (aq) --> Zn2+ (aq) + Cu(s)

            [ΔrG = -2FEcell  ]

But when the equation becomes

2Zn(s) + 2Cu2+ (aq) --> 2Zn2+ (aq) + 2Cu(s)

  [ΔrG = -4FEcell  ]

Problem:

The cell in which the following reactions occurs:

 has Eøcell = 0.236 V at 298 K. Calculate the standard Gibbs energy and the equilibrium constant of the cell reaction.

Solution:

By using the formula, 

  ΔrG = -nFEcell

= -2 X 96487 X 0.236

= - 45541.864 J mol-1

= - 45.54 KJ mol-1

Now,

Share these Notes with your friends  

< Prev Next >

You can check our 5-step learning process


.