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Redox Reactions and standard emf calculations

  • Thread starter kumarium
  • Start date
  • #1
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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!
 

Answers and Replies

  • #2
Borek
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What equations have you learned while studying redox potentials?
 
  • #3
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E°cell = E°cathode - E°anode
E°cell = (RT/nF)(lnk)
E = E° - (0.0592/n)(logk)
 
  • #4
Borek
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Why don't you just select the equation containing all known values and n? This is almost a simple plug and chug.
 
  • #5
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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
 
  • #6
Borek
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Yes.

When Q=K cell potential is zero.
 
  • #7
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Thank you for the help!
 

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