14.55

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Ashley Davis 1I
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Joined: Fri Sep 29, 2017 7:04 am

14.55

Postby Ashley Davis 1I » Thu Feb 22, 2018 2:04 am

How come the anode rxn's Eº = +1.23 V and not -1.23 V? In the book the reaction is written O2 + 4H+ + 4e- → 2H2O with Eº = +1.23 V. Since they've switched the reaction here, why isn't it -1.23?

Kelly Kiremidjian 1C
Posts: 62
Joined: Fri Sep 29, 2017 7:04 am

Re: 14.55

Postby Kelly Kiremidjian 1C » Thu Feb 22, 2018 10:03 am

You don't have to switch the sign of Eº if when calculating Eºcell you always use Eºcathode-Eºanode.

If you prefer to use the method where you add the Eºcathode and Eºanode you must flip the Eºanode.

Erica Nagase 1H
Posts: 30
Joined: Sat Jul 22, 2017 3:00 am

Re: 14.55

Postby Erica Nagase 1H » Thu Feb 22, 2018 10:13 am

Dr. Lavelle discussed 2 methods to calculate Ecell. The first method is to use Eocell = Eocathode - Eoanode, and you wouldn't switch the signs for the Eo here. The second method is to add Eo of the two half-reactions together, and you would switch the sign for the oxidation reaction Eo because the standard reduction potential tables lists the reduction half-reactions.


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