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cathode vs anode

Posted: Thu Feb 28, 2019 5:05 pm
by Athena L 1B
When you are given something like H+ and H2 with Ni2+ and Ni, how do you know which pair is the cathode and which is the anode?

Re: cathode vs anode

Posted: Thu Feb 28, 2019 5:08 pm
by Lauren Ho 2E
You can determine the cathode reaction and anode reaction by seeing which combination would cause you to end up with a greater voltage when the two reactions are combined

Re: cathode vs anode

Posted: Thu Feb 28, 2019 6:16 pm
by EllaBerry
The Ecell must be positive, and so you use the Ecathode -Eanode equation to determine which reaction is the cathode and anode by looking at the values you get when you put the E of one reaction in the cathode place and the other in the anode place. If the value is positive, the place you have the E values in are correct and you can look at the corresponding reactions to see which is cathode and which is anode.

Re: cathode vs anode

Posted: Thu Feb 28, 2019 7:05 pm
by Carissa Young 1K
whichever half-rxn is oxidized (loses e-, oxidation number incr) is the anode and the half-rxn that is reduced (gain e-, oxidation number decr) is the cathode

Re: cathode vs anode

Posted: Thu Feb 28, 2019 7:25 pm
by Jerome Mercado 2J
Note if Ecell is negative that means it is the opposite notation. So either flip the sign of Ecell and flip the notation as well if given a negative Ecell.