Redox Reactions and standard emf calculations

In summary, the conversation discusses using equations to find the value of n in a cell reaction with a standard emf of +0.17V and an equilibrium constant of 5.5 X 10^5 at 298K. The equation E = E°-(0.0592/n)(logk) is suggested as the most appropriate for this problem, and the value of n is calculated to be approximately 1.9989. It is also mentioned that when Q=K, the cell potential is zero.
  • #1
kumarium
4
0
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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  • #2
What equations have you learned while studying redox potentials?
 
  • #3
E°cell = E°cathode - E°anode
E°cell = (RT/nF)(lnk)
E = E° - (0.0592/n)(logk)
 
  • #4
Why don't you just select the equation containing all known values and n? This is almost a simple plug and chug.
 
  • #5
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
Yes.

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

Related to Redox Reactions and standard emf calculations

1. What is a redox reaction?

A redox reaction is a chemical reaction in which there is a transfer of electrons from one species to another. This transfer of electrons results in a change in the oxidation states of the species involved.

2. How do you determine the standard emf of a redox reaction?

The standard emf of a redox reaction can be determined by using the Nernst equation, which takes into account the standard reduction potentials of the species involved, as well as the concentrations and stoichiometric coefficients of the reactants and products.

3. What is the purpose of using standard emf in redox reactions?

The standard emf in redox reactions allows us to predict the direction and feasibility of a reaction, as well as the cell potential and the amount of energy released or consumed during the reaction.

4. How do you balance a redox reaction?

To balance a redox reaction, we must first identify the species being oxidized and reduced. Then, we balance the atoms and charges in each half-reaction by adding electrons. Finally, we balance the overall reaction by ensuring that the number of electrons transferred is equal in both half-reactions.

5. Can redox reactions occur in non-aqueous solutions?

Yes, redox reactions can occur in non-aqueous solutions, such as in organic solvents. In these cases, the standard reduction potentials may be different due to the different solvation effects of the solvent. The Nernst equation can be used to calculate the standard emf in these situations as well.

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