Calculating E naught

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Rian Montagh 2K
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Joined: Fri Sep 28, 2018 12:15 am

Calculating E naught

Postby Rian Montagh 2K » Sat Mar 09, 2019 4:13 pm

When given two reduction half equations, how do you know which one to make the cathode and which to make the anode for calculating E naught of the overall reaction?

Adrian C 1D
Posts: 60
Joined: Fri Sep 28, 2018 12:19 am

Re: Calculating E naught

Postby Adrian C 1D » Sat Mar 09, 2019 4:23 pm

You would have to determine which of the reactions is more easily reduced and that will be your cathode. You will have to compare the absolute values of the cell potentials. A helpful tip to remember is that you don't want a negative E naught.

Cole Doolittle 2K
Posts: 30
Joined: Fri Sep 28, 2018 12:20 am

Re: Calculating E naught

Postby Cole Doolittle 2K » Sat Mar 09, 2019 4:47 pm

Given the reduction half reactions, you will use the appendix to find E naught values. The lower E naught value is the anode because it is the stronger reducing agent. Then, to get E naught of the cell you do cathode - anode = E naught cell

Jennifer Su 2L
Posts: 47
Joined: Wed Nov 21, 2018 12:20 am

Re: Calculating E naught

Postby Jennifer Su 2L » Sat Mar 09, 2019 6:46 pm

You arrange it so that Enot is the most positive. So you should assign the half reaction with the larger Enot as cathode, and assign the half reaction with the smaller Enot as the anode. This way, Enot(cathode)-Enot(anode) will be the largest possible.

Helen Mejia 1I
Posts: 67
Joined: Fri Sep 28, 2018 12:24 am

Re: Calculating E naught

Postby Helen Mejia 1I » Sun Mar 10, 2019 9:49 am

Always remember that the goal is to have a positive E naught because a positive value indicates that it is spontaneous.

Lisa Werner 2F
Posts: 72
Joined: Fri Sep 28, 2018 12:17 am

Re: Calculating E naught

Postby Lisa Werner 2F » Sun Mar 10, 2019 5:56 pm

when you find the two half reactions in the from of reductions from an original equation, whichever one has the reactants and product on the same side as the original is the cathode and the one where the reactants and products are flipped is the anode.


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