The cell potential of a redox reaction occurring in an electrochemical cell unde
ID: 592932 • Letter: T
Question
The cell potential of a redox reaction occurring in an electrochemical cell under any set of temperature and concentration conditions can be determined from the standard cell potential of the cell using the Nernst equation E = E° RT nF ln Q where E is the cell potential of the cell, E° is the standard cell potential of the cell, R is the gas constant, T is the temperature in kelvin, n is the moles of electrons transferred in the reaction, and Q is the reaction quotient. Use this relationship to answer the problem below. For the following oxidation-reduction reaction 3 Ni2+(aq) + 2 Au(s) 3 Ni(s) + 2 Au3+(aq) the standard cell potential is 1.76 V. What is the actual cell potential of the cell if the temperature is 315 K, the initial Ni2+ concentration is 0.00109 M, and the initial Au3+ concentration is 0.000154 M? (Note that the reaction involves the transfer of 6 moles of electrons, and the reaction quotient is 18.3.)
Explanation / Answer
3 Ni2+(aq) + 2 Au(s) 3 Ni(s) + 2 Au3+(aq)
Eocell = - 1.76 V
Q = [Au+3]^2 / [Ni+2]^3
= (0.000154)^2 / (0.00109)^3
Q = 18.3
Ecell = Eo - RT / n F ln Q
= - 1.76 - 8.314 x 315 / 6 x 96485 ln 18.3
= - 1.76 - 0.004524 ln 18.3
Ecell = - 1.77 V
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