A) Use the standard reduction potentials located in the \'Tables\' linked above

Question

A) Use the standard reduction potentials located in the 'Tables' linked above to calculate the equilibrium constant for the reaction:

Ni2+(aq) + Cu(s) ---> Ni(s) + Cu2+(aq)

Hint: Carry at least 5 significant figures during intermediate calculations to avoid round off error when taking the antilogarithm.

Equilibrium constant: __________ delta G° for this reaction would be _________ ( greater /less ) than zero.

B) What is the calculated value of the cell potential at 298K for an electrochemical cell with the following reaction, when the Cu2+ concentration is 4.38×10-4 M and the Al3+concentration is 1.08 M ?
3Cu2+(aq) + 2Al(s)----> 3Cu(s) + 2Al3+(aq)
Answer: ______ V
The cell reaction as written above is spontaneous for the concentrations given:____ ( TRUE/FALSE )

Explanation / Answer

A)

    Ni2+(aq) + Cu(s) ---> Ni(s) + Cu2+(aq)

E0cell = E0cathode - E0anode

         =   -0.25 -0.337

         = -0.587 V

DG0 = -nFE0cell

     = -2*96500*-0.587

     = 113.291 kj

DG0 = - RTlnK

113291 = -8.314*298lnk

k = 1.384*10^-20

DG0 is greater than zero.

B) 3Cu2+(aq) + 2Al(s)----> 3Cu(s) + 2Al3+(aq)

E0cell = E0cathode - E0anode

         = 0.337 - (-1.662)

          = 1.997 V

Ecell = E0cell - 0.0591/nlog[Al3+]^2/[cu2+]^3

      = 1.997 -(0.0591/6)log((4.38*10^-4)^2/1.08^3)

Ecell = 2.064 V

as E0cell is +ve , the reaction is spontaneous.

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