4) So far, we have looked at finding cell potentials under standard conditions, however in reality, we are seldom at standard conditions. Recall that our equation for the Gibbs free energy at nonstandard conditions was AG=AG+RTINQ By substituting -nFE for G in the above equation we come to the Nernst equation (shown below), which gives a way to predict E under any conditions, not just standard conditions. In this equation, R is the gas constant (8.314 J mol K). F is the Faraday Constant (96480 C mol) and Q is the reaction quotient. RT E=E no cell The Nemst equation is extremely powerful, and can be written in a slightly more useful form. First, the natural log (In) can be replaced by log base 10 (log) by multiplying by 2.3 (InQ = 2.3logQ), and we can rearrange terms to put the equation into the form of a straight line, as shown. El 2.3RT nFlogQ+ Ecell a) Consider this form of the Nernst equation, sketch a plot of E. vs logQ. b) Notice that the term "-(2.3*RT/nF)" is made up entirely of constants except for "n". Solve for the value of this at 298 K, you may leave "n" as a variable. c) How does the 'term' in part b, correspond to the plot you drew in part a?

4) So far, we have looked at finding cell potentials under standard conditions, however in reality, we are seldom at standard conditions. Recall that our equation for the Gibbs free energy at nonstandard conditions was AG=AG+RTINQ By substituting -nFE for G in the above equation we come to the Nernst equation (shown below), which gives a way to predict E under any conditions, not just standard conditions. In this equation, R is the gas constant (8.314 J mol K). F is the Faraday Constant (96480 C mol) and Q is the reaction quotient. RT E=E no cell The Nemst equation is extremely powerful, and can be written in a slightly more useful form. First, the natural log (In) can be replaced by log base 10 (log) by multiplying by 2.3 (InQ = 2.3logQ), and we can rearrange terms to put the equation into the form of a straight line, as shown. El 2.3RT nFlogQ+ Ecell a) Consider this form of the Nernst equation, sketch a plot of E. vs logQ. b) Notice that the term "-(2.3*RT/nF)" is made up entirely of constants except for "n". Solve for the value of this at 298 K, you may leave "n" as a variable. c) How does the 'term' in part b, correspond to the plot you drew in part a?

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter18: Electrochemistry

Section: Chapter Questions

Problem 5RQ: The Nernst equation allows determination of the cell potential for a galvanic cell at nonstandard...

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