Why do we flip E for oxidation?

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Cindy Adiwidjaja 1B
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Why do we flip E for oxidation?

Postby Cindy Adiwidjaja 1B » Sun Mar 08, 2020 10:02 pm

I know that E is given, however, why do we need to flip the sign when we are trying to use the E for oxidation?

Tracy Tolentino_2E
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Re: Why do we flip E for oxidation?

Postby Tracy Tolentino_2E » Sun Mar 08, 2020 10:04 pm

Because all the E potentials are given as reduction values. You have to flip this value to get the oxidation value.

Zoya Mulji 1K
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Re: Why do we flip E for oxidation?

Postby Zoya Mulji 1K » Sun Mar 08, 2020 10:06 pm

If you are just using the cathode - anode equation you don't need to flip any numbers because the minus sign takes care of that. But, if you are using the method of writing out the half reactions and making the net equation, you'll have to make sure you flip the E for the oxidation half reaction.

TarynD_1I
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Re: Why do we flip E for oxidation?

Postby TarynD_1I » Sun Mar 08, 2020 10:08 pm

If using the equation E(cell) = E(cathode) - E(anode) and using reduction values found in the appendix or on the sheet he will give us on the test, then I'm pretty sure that there is no need to flip the anode cell potential value when accounting for oxidation. In this case you would not need to change the sign from Ecell given for standard reduction.

Niharika 1H
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Re: Why do we flip E for oxidation?

Postby Niharika 1H » Sun Mar 08, 2020 10:12 pm

In the appendix, the equations are given as reductions. So, for the E for oxidation, we flip the reaction and change the sign of E.

Andrew F 2L
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Re: Why do we flip E for oxidation?

Postby Andrew F 2L » Sun Mar 08, 2020 10:16 pm

What I found was confusing was that in Youtube videos, the teachers would be adding the cell potentials while the book has us subtract the anode from the cathode. These are both the same thing it is just that, like others have said, you don't change the standard potential sign when you are using the subtraction method.

ABombino_2J
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Re: Why do we flip E for oxidation?

Postby ABombino_2J » Sun Mar 08, 2020 10:17 pm

You are only supposed to flip E when you are given reduction potentials and you are looking for oxidation potentials. This is almost all the time becase our appendix gives reduction potentials.

Deena Doan 2F
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Re: Why do we flip E for oxidation?

Postby Deena Doan 2F » Sun Mar 08, 2020 10:45 pm

Since it is given in cell potential, that means that it is a reduction. So, to get oxidation, you flip it.

Cindy Adiwidjaja 1B
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Joined: Sat Jul 20, 2019 12:15 am

Re: Why do we flip E for oxidation?

Postby Cindy Adiwidjaja 1B » Sun Mar 08, 2020 10:48 pm

Will we always be given E for reduction? Is that just common convention or will there be a time when we get oxidation?

Gerald Bernal1I
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Re: Why do we flip E for oxidation?

Postby Gerald Bernal1I » Sun Mar 08, 2020 11:01 pm

You do not flip the sign if you are calculating the standard cell potential for the anode value.

Hussain Chharawalla 1G
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Re: Why do we flip E for oxidation?

Postby Hussain Chharawalla 1G » Sun Mar 08, 2020 11:15 pm

Be careful that if you are using the formula Ecell= Ecathode- Eanode then you would NOT change the sign

Eugene Chung 3F
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Re: Why do we flip E for oxidation?

Postby Eugene Chung 3F » Sun Mar 08, 2020 11:19 pm

Cindy Adiwidjaja 1B wrote:I know that E is given, however, why do we need to flip the sign when we are trying to use the E for oxidation?


Honestly, for me, I feel like it's easier to do Cathode-anode, that way you don't have to worry about changing the E value given.

Ryan_K_1K
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Re: Why do we flip E for oxidation?

Postby Ryan_K_1K » Sun Mar 08, 2020 11:20 pm

flipping E simply changes it from reduction to oxidation

Brandon Valafar
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Re: Why do we flip E for oxidation?

Postby Brandon Valafar » Sun Mar 08, 2020 11:28 pm

You flip E for oxidation because all the E values are given for reduction reactions. Therefore to flip the reactions to oxidation you have to also flip the E.


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