Redox Reactions and standard emf calculations

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Discussion Overview

The discussion revolves around the calculation of the value of n in a redox reaction given the standard emf and the equilibrium constant. It includes the application of relevant equations related to redox potentials and the conditions under which they are applied.

Discussion Character

  • Homework-related, Mathematical reasoning

Main Points Raised

  • One participant asks for the appropriate equation to determine the value of n based on given parameters of standard emf and equilibrium constant.
  • Another participant lists several equations related to redox potentials, including the Nernst equation and the relationship between standard cell potential and equilibrium constant.
  • A suggestion is made to select an equation that includes all known values to simplify the calculation.
  • A participant proposes using the equation E = E° - (0.0592/n)(logk) and demonstrates a calculation to find n, assuming E to be zero when Q equals K.
  • A later reply confirms the assumption that the cell potential is zero when the reaction is at equilibrium.

Areas of Agreement / Disagreement

Participants generally agree on the equations to use for the calculations, but there is no explicit consensus on the interpretation of the assumptions made in the calculations.

Contextual Notes

There are assumptions regarding the conditions under which the equations are applied, particularly the assumption that E can be considered zero at equilibrium, which may depend on the context of the problem.

Who May Find This Useful

Students studying redox reactions, those interested in electrochemistry, and individuals looking to understand the application of Nernst equation in practical scenarios.

kumarium
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What is the equation I should be using for the following question:

At 298K a cell reaction has a standard emf of +0.17V. The equilibrium constant for the cell reaction is 5.5 X 10^5. What is the value of n for the cell reaction.

Grateful for anyone's help!
 
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What equations have you learned while studying redox potentials?
 
E°cell = E°cathode - E°anode
E°cell = (RT/nF)(lnk)
E = E° - (0.0592/n)(logk)
 
Why don't you just select the equation containing all known values and n? This is almost a simple plug and chug.
 
The equation that should be most likely used is E = E°-(0.0592/n)(logk).
I have the value for the standard emf = E°, and value of k.

Do I assume E to be zero then? If I do so, then the solution should look like the following:
0= E° - (0.0592/n)(logk)
0= 0.17 - (0.0592/n)(log(5.5*10^5))
0.17 = (0.0592/n)(log(5.5*10^5))
n= (0.0592)(log(5.5*10^5)) / 0.17
n= 1.9989
 
Yes.

When Q=K cell potential is zero.
 
Thank you for the help!
 

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