## Finding n

$\Delta G^{\circ} = -nFE_{cell}^{\circ}$

Michelle Choi 1H
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Joined: Tue Nov 17, 2015 3:00 am

### Finding n

I'm still confused on how to find the number of moles in the formula for Gibbs. Is it the number of electrons that you gain/lose from both the half reactions??

GutierrezCruz_1J
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Joined: Fri Sep 25, 2015 3:00 am

### Re: Finding n

n is the moles of e- transferred in the overall reaction. Which is equivalent to the overall charges of the reactants and the products in the balanced equation. The example that helps is on Pg. 52 of the course reader. Hopes this helps.

Michael Lee 2I
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### Re: Finding n

n is just the amount of electrons transferred in the reaction. Usually you need to find the half reactions first.

Guangyu Li 2J
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### Re: Finding n

According to the textbook, n is the number of electrons transferred in moles. Commonly we can first list the half-rxns to identify how many moles of electrons are transferred.

Emma Miltenberger 2I
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### Re: Finding n

N is the number of electrons transferred in the reaction. To find this value, first balance the reaction so the electrons gained match the electrons lost. This is the value you should use for n.

Posts: 31
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### Re: Finding n

n is the number of electrons transferred in the half reactions, but they need to be balanced first.

Brandon Fujii 1K
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### Re: Finding n

An example might be:

if the oxidation half reaction produces 2 mol of e-
and reduction half reaction produces 3 mol of e-

you’d have to multiply the oxidation half rxn by a factor of 3 and the reduction half rxn by a factor of 2 because the moles of e- must cancel

in this case 2mol e- * 3 = 6mol e-
and 3mol e- * 2 = 6mol e-

n=6 mol e-

Leah Thomas 2E
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Joined: Fri Sep 29, 2017 7:06 am

### Re: Finding n

To accurately find n, you must first balance the equation with the correct amount of moles, water, and hydrogen molecules so electrons can cancel out.

Diego Zavala 2I
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### Re: Finding n

To find n, first balance the half reactions. Then multiple each half reaction with a coefficient that will allow you to cross out the moles of electrons on both half reactions. (i.e if one half reaction has 1 electron on the reactant side and the other half reaction has 4 electrons on the product side, then multiple the first half reaction by 4). n will be equal to the moles of electrons that were crossed out (in the last example, n=4)

Justin Folk 3I
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### Re: Finding n

How do we know it's a mole of reaction?

Ilan Shavolian 1K
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### Re: Finding n

Justin Folk 3I wrote:How do we know it's a mole of reaction?

What do you mean?? It's the moles of electrons in the balanced reaction.

Justin Folk 3I
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### Re: Finding n

But if you multiply entire reaction by 2 then why isn’t it using 2 moles?

Christy Zhao 1H
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Joined: Fri Sep 29, 2017 7:07 am

### Re: Finding n

If a half reaction is multiplied by 2 to get an equal number of moles of electrons in both half reactions to be able to cancel each other out, then yes n=2.

Rishi Khettry 1L
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### Re: Finding n

n is the number of electrons

Cynthia Bui 2H
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### Re: Finding n

n = number of electrons

CalebBurns3L
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Joined: Fri Sep 29, 2017 7:07 am

### Re: Finding n

You're going to need to split up the reaction into its half reactions. And then you're going to balance it so the electrons cancel and use that final number of electrons as the n.