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Topic: Need help calculating reduction potential using Nernst Equation  (Read 3982 times)

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Offline user1000

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Need help calculating reduction potential using Nernst Equation
« on: September 13, 2014, 08:19:23 AM »
I'm unsure of how to solve these problems:

At pH=0 the standard reduction potential for the reaction Ni2+(aq) + 2e--->  Ni(s)  is   Eo = -0,25V

At pH=14, the reaction can be written as: Ni(OH)2(s)-->Ni(s) + 2OH-(aq)

Ksp(Ni(OH)2) = 5,5X10^(-16)M3

 1)  What is the reduction potential for reduction of Ni(II) to Ni(s) at pH = 14 and 25 *C?

 2) What is the standard reduction potential for     Ni(OH)2(s) + 2e-  -->   Ni(s) + 2OH(aq)       at pH = 14? Reflect on your answer

I'm supposed to set up nernst equation based on the reaction at pH=0, and then the equation for [Ni2+] at pH=14 using data from the former

Any help would be greatly appreciated




Offline Borek

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Re: Need help calculating reduction potential using Nernst Equation
« Reply #1 on: September 13, 2014, 09:29:19 AM »
What does it mean "standard potential"?

Think how concentration of Ni2+ changes with pH.
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Offline user1000

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Re: Need help calculating reduction potential using Nernst Equation
« Reply #2 on: September 13, 2014, 10:09:34 AM »
What does it mean "standard potential"?

Think how concentration of Ni2+ changes with pH.

Thanks

I can find [Ni2+] from the ksp equation because [OH-]=1 at pH 14, and then use nernst equation to find E; However, I'm not sure if thats correct

I have pondered on this for a long time now. It's part of a mandatory assignment that is due to tomorrow





Offline Borek

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Re: Need help calculating reduction potential using Nernst Equation
« Reply #3 on: September 13, 2014, 01:39:40 PM »
I can find [Ni2+] from the ksp equation because [OH-]=1 at pH 14, and then use nernst equation to find E

That's the correct approach.
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