Fe3+ concentration in galvanic cell with Pt cathode and Cu anode

[Maxwell]

Help! (Repost from Chemistry board)

So far I have done 14 out of 15 questions on the LAST problem set of the semester.

I am stuck on one question, and no matter what I try, it won't accept my answer (the problem set is electronic).

Here is the problem:

"A galvanic cell consists of a Pt cathode inmmersed in a solution containing Fe2+ at 2.15 M and Fe3+ at unknown concentration, as well as a Cu anode immersed in a 2.30 M solution of Cu2+. The cell voltage is 0.09 V. What is the concentration of Fe3+ ions? Enter your answer in M."

Since I tried the problem so many times, the computer gave me a hint:

"Hint: The platinum is acting as the cathode, and the copper is acting as the anode in this cell. Calculate the Eo for this cell, and given the actual emf, work backwards with the Nernst equation to calculate concentrations. Don't forget to count the number of electrons being transferred."

Anytime I ask someone in my class how they did it, I get a generic answer like "my friend did it".

PLEASE help me on this, this is the LAST problem set question of the semester!

Thank you..

(PS - I also posted this on the Chemistry board, just incase someone who can help does not check the chem board.)

 

[Maxwell]

I got the answer, nevermind.

 

[M98Ranger]

Hello, it looks like you are having trouble with a specific chemistry problem. I would recommend trying the hint that the computer gave you - calculate Eo for the cell and use the Nernst equation to work backwards and calculate the concentration of Fe3+ ions. Also, don't forget to count the number of electrons being transferred. If you still need help, I would suggest reaching out to your professor or a tutor for further assistance. Good luck!