June 18, 2021, 11:57:01 PM
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### Topic: Calculate the concentration of Ni2+ if the cell is allowed to run to equilibrium  (Read 170 times)

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#### Judy

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##### Calculate the concentration of Ni2+ if the cell is allowed to run to equilibrium
« on: June 07, 2021, 12:18:05 AM »
Consider an electrochemical cell with a zinc electrode immersed in 1.0M Zn 2+ and a nickel electrode immersed in 0.10 M Ni 2+.

Zn 2+ + 2e-  → Zn   E° = -0.76 V
Ni 2+ + 2e-   → Ni    E° = -0.23 V

Calculate the concentration of Ni2+ if the cell is allowed to run to equilibrium at 25°C.

A) 1.10 M
B) 1.20 M
C) 0.10 M
D) 0 M
E) none of those

Here's my calculation:
Zn + Ni2+ -> Zn2+ + Ni
0.53 = 0.059/2*log([Zn2+]/[Ni2+])
Since only the initial concentrations of both ions are given and the zinc ion concentration at equilibrium isn't given, it isn't possible to calculate nickle ion concentration at equilibrium. Is my reasoning correct? Thanks.

#### Borek

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##### Re: Calculate the concentration of Ni2+ if the cell is allowed to run to equilibrium
« Reply #1 on: June 07, 2021, 02:49:00 AM »
Hint: they react till the E of the cell equals 0. That's where the equilibrium lies.
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#### Judy

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##### Re: Calculate the concentration of Ni2+ if the cell is allowed to run to equilibrium
« Reply #2 on: June 07, 2021, 03:24:14 AM »

Hint: they react till the E of the cell equals 0. That's where the equilibrium lies.
[/quote]
Thanks for your reply. I don't quite get the hint. Based upon my calculation, there are two variables (concentration of zinc and nickle ions), so the answer is E?

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