Non-standard cell potential problem

[higherme]

Homework Statement

given:
Sn2+ + 2e- --> Sn(s) E standard = -0.14 V
Tl+ + e- ---> Tl(s) E standard = -0.34 V

find the standard cell potential.
and, what the cell potential would be if concentration of each of the ionic species involved is 2.9mM. assume dilute ideal behaviour and standard conditions for gases involved.

The Attempt at a Solution

I found the standard potential to be: -0.14 - (-0.34) = 0.20V

now, do i use the nernst equation for the next part of the question??

 

[nate808]

Thank you for your post. Yes, you are correct in using the Nernst equation to calculate the cell potential under the given conditions. The Nernst equation is as follows:

Ecell = Estandard - (RT/nF)ln(Q)

where:
Ecell = cell potential under non-standard conditions
Estandard = standard cell potential
R = gas constant (8.314 J/mol*K)
T = temperature (in Kelvin)
n = number of moles of electrons transferred in the balanced half-reaction
F = Faraday's constant (96,485 C/mol)
Q = reaction quotient (concentration of products/concentration of reactants)

To calculate Q, you will need to use the concentrations of Sn2+ and Tl+ under the given conditions. Since the concentrations are given in mM, you will need to convert them to mol/L by dividing by 1000. The reaction quotient can then be calculated as follows:

Q = [Sn2+] / [Tl+]

Substitute the values into the Nernst equation and solve for Ecell. This will give you the cell potential at the given concentrations. Remember to use the correct sign for the cell potential (-0.20 V in this case) as it will determine whether the reaction is spontaneous or not.

I hope this helps. Good luck with your calculations!

 

[Blueshift5]

Yes, you would use the Nernst equation to calculate the cell potential at non-standard conditions. The Nernst equation allows you to calculate the cell potential when the concentrations of the species involved are not at standard conditions. In this case, the concentration of Sn2+ and Tl+ are given as 2.9mM, so you would substitute these values into the Nernst equation along with the standard potential and temperature to calculate the cell potential. The Nernst equation is: Ecell = Estandard - (RT/nF)ln(Q), where R is the gas constant, T is the temperature in Kelvin, n is the number of moles of electrons transferred, F is Faraday's constant, and Q is the reaction quotient. Remember to adjust the concentration of the species according to their stoichiometric coefficients in the balanced equation before substituting into the Nernst equation.