Cell Potential with Nernst Equation

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SUMMARY

The discussion centers on the application of the Nernst Equation to calculate cell potential in electrochemistry. The user calculated the standard cell potential (E°) as 0.012 V using the formula E° = E°(cathode) - E°(anode) with values -0.131 V and -0.143 V. The user encountered difficulties in determining the correct cell potential, ultimately calculating E as 0.0023 V, which was marked incorrect despite following the Nernst Equation correctly. The user plans to consult their professor regarding the discrepancy in the homework grading.

PREREQUISITES
  • Understanding of the Nernst Equation and its components
  • Knowledge of standard electrode potentials
  • Familiarity with logarithmic functions and their application in chemistry
  • Basic principles of electrochemistry, including oxidation and reduction reactions
NEXT STEPS
  • Review the Nernst Equation and its derivation for different electrochemical cells
  • Study the concept of reaction quotient (Q) in relation to equilibrium
  • Learn about standard electrode potential tables and their usage
  • Explore common mistakes in electrochemical calculations and how to avoid them
USEFUL FOR

This discussion is beneficial for chemistry students, particularly those studying electrochemistry, as well as educators seeking to clarify common misconceptions regarding the Nernst Equation and cell potential calculations.

davev
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Homework Statement


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Homework Equations


Nernst Equation where Q = [product]/[reactants], R = 8.314, F = 96500
nernst.gif

The Attempt at a Solution


I got E° to be 0.012 V because E° of cathode - E° of anode. -0.131 - (-0.143) = 0.012.

The balanced equation I got was: Pb2+ + Sn → Pb + Sn2+

For the values of Q, I added 0.349 M to the concentration of Sn2+ as it's the product, and I subtracted 0.349 M from the concentration of Pb2+ as it's the reactant.

Plugging everything into the equation:
E = 0.012 V - ((8.314 * 271)/(2 * 96500)) * ln(1.318/0.576) = 0.0023 V. This answer is wrong, but I cannot figure out what I'm doing wrong here. Please help!
 
Last edited:
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I can't find anything wrong.

Not that I am infallible, but there are two of us stumped now.
 
The answer I put in is what the system shows as the correct answer now that the homework has closed. I don't understand why it was marked incorrect, but I'll just have to email my professor.
 

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