Standard cell potential and equilibrium

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chloewinnett1L
Posts: 55
Joined: Fri Sep 28, 2018 12:20 am

Standard cell potential and equilibrium

Postby chloewinnett1L » Thu Mar 14, 2019 10:09 pm

Why does a positive standard cell potential correspond to K>1?

Alana Sur 3B
Posts: 61
Joined: Fri Sep 28, 2018 12:25 am

Re: Standard cell potential and equilibrium

Postby Alana Sur 3B » Thu Mar 14, 2019 10:16 pm

because natural log of any value greater than 1 is positive. the formula used is E = (RT/nF)(ln K)
Last edited by Alana Sur 3B on Thu Mar 14, 2019 10:17 pm, edited 1 time in total.

Tiffany_Cacy_3D
Posts: 70
Joined: Fri Sep 28, 2018 12:24 am

Re: Standard cell potential and equilibrium

Postby Tiffany_Cacy_3D » Thu Mar 14, 2019 10:16 pm

Positive standard cell potential correlates to K>1 because of the equation Delta G=-nFE. This shows that whenever E is positive, Delta G will be negative (moles are never negative and F is a positive constant). When Delta G is negative this means the reaction will be spontaneous and will favor products, or in other words K>1.

StudentD2B
Posts: 43
Joined: Fri Sep 28, 2018 12:27 am
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Re: Standard cell potential and equilibrium

Postby StudentD2B » Thu Mar 14, 2019 10:26 pm

For a general reaction of the type aA + bB → cC + dD, the standard free-energy change and the equilibrium constant are related by the following equation: ΔG° = −RT lnK. Given the relationship between the standard free-energy change and the standard cell potential: ΔG° = −nFE°cell, we can write: −nFE°cell = −RT lnK. If you rearrange the equation to solve for E°cell, you get: E°cell = (RT/nF) lnK Thus E°cell is directly proportional to the logarithm of the equilibrium constant. This means that large equilibrium constants correspond to large positive values of E°cell and vice versa.


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