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Topic: Electrochemistry II  (Read 1086 times)

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Offline INeedSerotonin

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Electrochemistry II
« on: October 18, 2019, 01:52:30 PM »
The silver zinc oxide electrochemical cell, used to power hearing aids and wristwatches, is based on the following half reactions, written as a reduction:
   
        Zn2+   +    2e-   -->   Zn(s)                         ε0 = - 0,763 V
   Ag2S(s)   +   H2O(l)   +   2e-  --> 2Ag(s)  +    2OH-             ε0 = + 0,344 V

The table below indicates some possible relationships between the characteristics presented by this cell.



   The frame line that corresponds to the correct relationship set is
(A)  I.
(B)  II.
(C)  III.
(D)  IV.
(E)  V

I have no idea how to solve this. Could you guys give me a hint (or a couple of hints)? I don't get the "positive pole" part. How come it is "cathode"? Where does this come from? Isn't zinc the anode?

Offline chenbeier

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Re: Electrochemistry II
« Reply #1 on: October 18, 2019, 03:30:33 PM »
Zinc is anode, because it will oxidized. E0 = Ered - Eox. = 0,344 V -(-0,763V) =1,107 V

Offline mjc123

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Re: Electrochemistry II
« Reply #2 on: October 21, 2019, 04:37:13 AM »
Yes, zinc is the anode. It is not the "positive pole". You are being asked three separate questions.

Offline Enthalpy

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Re: Electrochemistry II
« Reply #3 on: October 21, 2019, 01:42:59 PM »
Metallic zinc is the negative electrode. Whether it's the anode or cathode...

Chemists follow the initial definition for that.

The rest of the world, even the documents of battery manufacturers, follow different conventions. Just be aware of that.

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