Selecting Anode & Cathode for Cu2(SO4) & Fe(SO4) Flow Battery

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Discussion Overview

The discussion centers around the selection of anode and cathode materials for a flow battery utilizing aqueous solutions of 1 M Cu2(SO4) and Fe(SO4). Participants explore the underlying chemistry and reactions involved in the battery's operation, including the roles of Copper (I) and Iron (II) ions.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • A graduate student seeks clarification on why Copper (I) and Iron (II) are selected as anode and cathode materials, respectively.
  • One participant asserts that anode and cathode must be conductive solids or liquids, not single ions.
  • A participant provides specific half-reactions for the anode and cathode but expresses confusion about the selection of these materials over others.
  • Another participant emphasizes the distinction between cathode and anode materials versus the reactions occurring at those electrodes.
  • There is a suggestion that the overall cell potential (E°) must be negative for an electrolytic cell, but the reasoning behind the choice of Copper (I) and Iron (II) remains unclear to some participants.

Areas of Agreement / Disagreement

Participants express differing views on the selection criteria for anode and cathode materials, with no consensus reached on the appropriateness of using Copper (I) and Iron (II) in this context.

Contextual Notes

There are unresolved questions regarding the definitions of anode and cathode materials versus the reactions, as well as the implications of the overall cell potential in the context of an electrolytic cell.

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A graduate student is trying to develop a flow battery based on aqueous solutions of 1 M Cu2(SO4) and Fe(SO4) (recall that the sulfate is divalent, e.g. (SO4)-2 and assume complete solubility).

Given a chart like this : CHART

How would I know that I need to select Copper (I) and Iron (II) as my anode and cathode, respectively?

I haven't taken chemistry before, so if anyone can explain in a concise way I'd really appreciate it.

Thanks!
 
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You can't select Cu(I) nor Fe(II) as anode or cathode - anode and cathode have to be a conductive solid (or liquid), you can't make them out of a single ion.
 


Sorry, I'm not really sure how to respond. The answer for this question on my last exam was:

Anode: 2Cu+ + 2e- → 2Cu
Cathode: Fe → Fe2+ + 2e-
Overall: Cu2(SO4) → Fe(SO4) + 2Cu

I am just confused as to why the anode and cathode were selected to be those two, as opposed to some other form of copper or iron...
 


These are not cathode and anode material, but cathode and anode reactions. If you don't know the difference you have a lot to learn, that's not a thing I can help you in a single post.

Look for any general chemistry material describing the cells, redox reactions and reactivity series.
 


This is supposed to be a pretty easy question, are there any tricks you can offer that may help me solve other ones (i.e. the cathode is usually the reaction we flip and make the potential negative)? Also, I'm still confused as to why we chose Copper(I) and Iron(II) instead of some other form...
 


Cu(I) and Fe(II) are part of the two solutions that you are given, that is why you are using them. As for your anode and cathode, I believe you must choose so that your overall E° is negative, as this is an electrolytic cell and the E° is always negative in an electrolytic cell. At least that's what I remember. Anyone care to clarify? My chemistry is a little rusty.
 

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