Electrochemical Cell: Electrode at Cathode Irrelevant?

[justadream]

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Is the type of substance (as long as it is conducting) that is acting as the electrode at the cathode irrelevant?

For example, look at the Zinc/Copper battery.

Zinc becomes oxidizes to Zn2+.
Copper is reduced from Cu2+ to Cu.

The solid electrode in the anode matters (after all, the solid zinc becomes Zn2+) but the solid electrode in the cathode does not matter (because the copper ions in the solution will plate out - become solid - on whatever is the electrode at the cathode)?

 

[NextStepTutor_1]

For the purposes of the MCAT: yes, it is basically irrelevant as to the identity of the material at the cathode as long as it is conducting (metal) and a substance (usually copper is the example) can plate out on it.

Take for example, gold plating. Gold jewelry can be classified as "solid gold" or "gold plated." Solid gold is gold plated (or shaped, polished, etc. from a larger piece) onto itself, however gold plating is gold that has been plated onto another metal (something cheaper than gold normally). So the electrode at the cathode does not have to be of the same compound as what you are trying to plate out - i.e. the electrode does not have to be gold in order for gold to plate out.

Hope this helps!


http://forums.studentdoctor.net/forums/next-step-mcat-tutor-office-hours.970/

 

[justadream]

@NextStepTutor_1

Thanks for the reply!

Would this still apply for concentration cells?

 

[NextStepTutor_1]

@justadream - In a concentration cell, what normally occurs is a break down of the anode while some gas is produced at the cathode. See the picture for reference.

Source:
http://chemwiki.ucdavis.edu/Analyti...der_Nonstandard_Conditions/Concentration_Cell


More useful information: this (concentration cells) is not background info you need to know for the MCAT.

 

[justadream]

@NextStepTutor_1

Okay I see your point. But there are some concentration cells that don't produce a gas so I guess for those, the conducting substance at the cathode wouldn't matter?

Semi-Related Question:
Why is it that in concentration cells, the "anode" counts as the product while the "cathode" counts as the reactants when you calculate "Q" in the Nernst equation?