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Author Topic: How to calculate the voltage of an alkaline battery?  (Read 577 times)

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ForumUserGF

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How to calculate the voltage of an alkaline battery?
« on: May 16, 2018, 06:39:58 PM »

I just cannot get a voltage of 1.5V as the result. Here is what I have so far:

Code: [Select]
U = E0(cathode) – E0(anode)
 = 1,23 V - (-1,2 V)
 = 2,43 V

But this cannot be correct...
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sjb

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Re: How to calculate the voltage of an alkaline battery?
« Reply #1 on: May 16, 2018, 10:06:55 PM »

Well, the maths is right, but without seeing where this has come from, I'm not sure how to comment.
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ForumUserGF

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Re: How to calculate the voltage of an alkaline battery?
« Reply #2 on: May 17, 2018, 05:12:55 AM »

Well, the maths is right, but without seeing where this has come from, I'm not sure how to comment.

Well,

Oxydation: Zn + 4OH-   :rarrow:  [Zn(OH)4]2- + 2e-
Reduction: 2MnO2 + H2O + 2e-  :rarrow: Mn2O3 + 2OH-

And now you take E0(Mn2+/MnO2) = 1,23V and E0(Zn/Zn(OH)42-) = -1,199V. However, the result is wrong.
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sjb

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Re: How to calculate the voltage of an alkaline battery?
« Reply #3 on: May 17, 2018, 06:45:29 AM »

If the reduction is MnO2  :rarrow: Mn2O3 why are you using E° for a different half reaction?
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