Calculate cell potential when concentrations aren't 1M, but are the same.

In summary, to calculate the standard potential for a Cu2+ 0.5M, Zn2+ 0.5M cell, you can use the equation Ecell = E0cell - (RT/nF)lnQ, where the concentrations of both ions are 0.5M. Since the concentrations are the same and no half reactions are multiplied, the Q value is 1 and lnQ is 0. This means that the concentrations do not affect the final result in this case. However, this may not always be the case as the potentials of the half reactions can be shifted by different amounts.
  • #1
VertiGhost
2
0

Homework Statement


Calculate standard potential for a Cu2+ 0.5M, Zn2+ 0.5M cell.

Homework Equations


Ecell = E0cell - (RT/nF)lnQ

The Attempt at a Solution


So, I know at standard conditions it would simply be
Ecell = 0.340 - (-0.763)
Ecell = 1.103

It's the concentrations that are confusing me. If they are the same and no half reactions are multiplied, I get a Q value of 1.
lnQ = ln(1) = 0.
So in this case does it not matter what the concentrations are as long as they are the same?
 
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  • #2
In this case potentials of both half reactions are shifted by the same amount, so the final result stays the same. It doesn't have to be always this way.
 
  • #3
Sorry for the delayed thank you, but thank you :)
 

What is the formula for calculating cell potential when concentrations are not 1M?

The formula for calculating cell potential when concentrations are not 1M is E°cell = E°red + E°ox, where E°red is the standard reduction potential and E°ox is the standard oxidation potential.

How do I determine the standard reduction potential and standard oxidation potential?

The standard reduction potential and standard oxidation potential can be found in a standard reduction potential table, which lists the reduction and oxidation potentials for various half-reactions.

Do I need to convert the concentrations to 1M before calculating cell potential?

No, you do not need to convert the concentrations to 1M before calculating cell potential. The formula for calculating cell potential takes into account the concentrations of the species involved in the reaction.

Can I use the Nernst equation to calculate cell potential when concentrations are not 1M?

Yes, the Nernst equation can be used to calculate cell potential when concentrations are not 1M. It takes into account the concentrations of the species involved in the reaction, as well as the temperature and the number of electrons transferred.

What are some factors that can affect the accuracy of the calculated cell potential?

Some factors that can affect the accuracy of the calculated cell potential include temperature, ionic strength, and the presence of impurities or other reactants in the solution. It is important to use accurate and precise measurements of concentrations and to consider any potential interferences in the reaction.

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