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# Electrochemistry- Non-standard Conditions watch

1. The half cell
Cr2O7(2-) + 14H(+) + 6e(-) <==> 2Cr(3+) + 7H2O
has an E0 value of +1.33V. All concentrations are 1.0mol.dm-3.

Suggest an E(cell) value if
a) [Cr2O7(2-)] were to be increased.

Now, i'm having trouble getting this. Changing the concentration of this ion does affect the position of the equilibrium, but it shouldn't affect the E(cell) value at all (at least not much), since the E0 value gives the amount of energy with which the redox equation occurs and is unique to each ion. Now, I do recognise that by plugging this into the Nernst Equation
E = E0 + (RT)/zF loge[M(n+)]
with different values for [M(n+)] gives slightly different values, my question is (chemically) WHY?

Any help would be much appreciated.
Ta!

2. (Original post by UpsidedownLandMan)
The half cell
Cr2O7(2-) + 14H(+) + 6e(-) <==> 2Cr(3+) + 7H2O
has an E0 value of +1.33V. All concentrations are 1.0mol.dm-3.

Suggest an E(cell) value if
a) [Cr2O7(2-)] were to be increased.

Now, i'm having trouble getting this. Changing the concentration of this ion does affect the position of the equilibrium, but it shouldn't affect the E(cell) value at all (at least not much), since the E0 value gives the amount of energy with which the redox equation occurs and is unique to each ion. Now, I do recognise that by plugging this into the Nernst Equation
E = E0 + (RT)/zF loge[M(n+)]
with different values for [M(n+)] gives slightly different values, my question is (chemically) WHY?

Any help would be much appreciated.
Ta!

well, different amounts of M(n+) exert different amount of potential, the work done required to move a point charge over a distance r.

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