So I'm about to tear my hair out

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Discussion Overview

The discussion revolves around a specific problem from a chemistry problem set involving a galvanic cell. The participant seeks assistance in determining the concentration of Fe3+ ions based on given parameters, including cell voltage and concentrations of other ions. The scope includes mathematical reasoning and problem-solving in a homework context.

Discussion Character

  • Homework-related, Mathematical reasoning

Main Points Raised

  • The initial poster describes their struggle with a specific question regarding a galvanic cell and the use of the Nernst equation to find the concentration of Fe3+ ions.
  • One participant suggests that the poster should ensure the balanced equation for the half-cell reactions is correct and emphasizes the importance of arranging the reactions to yield a positive potential difference.
  • The initial poster expresses uncertainty but is willing to try again based on the advice given.
  • The initial poster later reports a calculated concentration but finds that the computer does not accept it.
  • The initial poster ultimately resolves the issue, stating that the computer required a specific number of significant figures for the answer.

Areas of Agreement / Disagreement

The discussion does not present significant disagreement, as the initial poster ultimately resolves their issue with the computer's acceptance of their answer. However, the initial poster's initial uncertainty about the correct approach indicates a lack of consensus on the method prior to receiving help.

Contextual Notes

The discussion highlights potential limitations in the initial poster's understanding of significant figures and the requirement for precision in electronic problem sets, which may not have been fully addressed in their earlier attempts.

Maxwell
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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..
 
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Let me help you with this step by step.

First write the correct balanced equation. It is important that your equation is correct. Remember that you need to arrange the half cell reactions so that the differences in the half cell potential is of a positive magnitude. I am sure you know how to do the rest. It is most likely that you did not write out the correct balanced equation or in dealing with Q.

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Maybe you are right, let me give it a few more tries.. Thanks for your help!

I will post my results as soon as i get them. Thanks again.
 
I got 5.8892383931813e-6.

The computer is not accepting it for some reason?
 
Nevermind! I got it, the stupid computer was expecting sig figs, and it wouldn't accept anything close.

Thanks again.
 

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