changing sign of of standard cell potentials

Moderators: Chem_Mod, Chem_Admin

Ishan Saha 1L
Posts: 60
Joined: Fri Sep 29, 2017 7:03 am

changing sign of of standard cell potentials

Postby Ishan Saha 1L » Mon Feb 26, 2018 1:47 pm

Are we allowed to change the sign (as in multiply by -1) of the standard cell potentials of the half reactions if we are looking for the standard cell potential of the reverse half reaction? I had thought that this was not possible because reversing a reduction half reaction makes it an oxidation reaction since the e- would be on the products side.

Chem_Mod
Posts: 17949
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 406 times

Re: changing sign of of standard cell potentials

Postby Chem_Mod » Mon Feb 26, 2018 2:02 pm

Technically, you can flip a reaction and change the by multiplying it by negative 1, as you said. Thus, by using the equation of , you can see that the standard cell potentials for reactions and their reverse counterparts are equal and opposite.

Anna Okabe
Posts: 30
Joined: Fri Sep 29, 2017 7:06 am

Re: changing sign of of standard cell potentials

Postby Anna Okabe » Mon Feb 26, 2018 9:13 pm

Yes, because the reverse half reaction of the reduction reaction that you are looking for is the oxidation reaction. Therefore you want the e- to be on the opposite side.

andrewr2H
Posts: 29
Joined: Fri Sep 29, 2017 7:05 am

Re: changing sign of of standard cell potentials

Postby andrewr2H » Mon Feb 26, 2018 9:20 pm

Yes you can flip the reaction and the sign of Eo, but if in the case you are determining cell potentials and you happen to be using the equation Ecell = Ecathode - Eanode, you would just keep the signs of the E cathode and E anode as given because the negative sign in the equation accounts for the sign flip.

905022356
Posts: 48
Joined: Mon Oct 02, 2017 7:19 am

Re: changing sign of of standard cell potentials

Postby 905022356 » Wed Feb 28, 2018 5:49 pm

So, if we are using the reduction electrode potentials, we do not change the sign when we imput the voltages into the equation?


Return to “Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams”

Who is online

Users browsing this forum: No registered users and 1 guest