Equation for Standard Cell Potential

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Reina Robles 2B
Posts: 71
Joined: Fri Aug 09, 2019 12:16 am

Equation for Standard Cell Potential

Postby Reina Robles 2B » Wed Feb 26, 2020 11:57 am

In the textbook, the standard cell potential of this reaction

Fe(s) + 2Ag⁺(aq) → Fe²⁺(aq) + 2Ag(s)

is

cell=E˚(Ag+/Ag)-E˚(Fe2+/Fe)

Why is it product/reactant for Fe, and reactant/product for Ag?

Thanks!

Hiba Alnajjar_2C
Posts: 108
Joined: Fri Aug 09, 2019 12:17 am

Re: Equation for Standard Cell Potential

Postby Hiba Alnajjar_2C » Wed Feb 26, 2020 12:20 pm

Standard potentials are given as reductions, not oxidations. Therefore, in the reduction of Fe2+, Fe2+ would be the reactant and Fe would be the product. In the given reaction, Fe2+ is being oxidized, which is why it's flipped and Fe2+ is the product rather than the reactant. But the standard potential is still given as a reduction. This is also why the standard potential of Fe is subtracted rather than added, since Fe is being oxidized (meaning you would have to reverse the reduction reaction and change the sign of the standard potential).

Reina Robles 2B
Posts: 71
Joined: Fri Aug 09, 2019 12:16 am

Re: Equation for Standard Cell Potential

Postby Reina Robles 2B » Sat Feb 29, 2020 1:59 pm

Hiba Alnajjar_2C wrote:Standard potentials are given as reductions, not oxidations. Therefore, in the reduction of Fe2+, Fe2+ would be the reactant and Fe would be the product. In the given reaction, Fe2+ is being oxidized, which is why it's flipped and Fe2+ is the product rather than the reactant. But the standard potential is still given as a reduction. This is also why the standard potential of Fe is subtracted rather than added, since Fe is being oxidized (meaning you would have to reverse the reduction reaction and change the sign of the standard potential).


I see, thank you!


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