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How cathode is positively charged in voltaic cell?

  1. Jan 26, 2015 #1
    How cathode is positively charged in voltaic cell?I mean at cathode reduction takes place ,but the electron which is gained for reduction comes from anode,than why cathode becomes positively charged ?As electrons are from anode not from cathode that means electrons are not lost by cathode ,so it should not become positively charged.Right?
     
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  3. Jan 26, 2015 #2
    cathode is said to be the positive electrode . its not positively charged . everything in nature is electrically neutral . we perceive it as separate charges for better understanding .
     
  4. Jan 27, 2015 #3
    Alright, this might be off topic BUT, I too am perplexed by the phenomenon of radioactive decay. How is electrical neutrality maintained when electrons (beta particles) and proton-neutron sets (alpha particles) are being spit out by some elements. These particles are whizzing by all the other neutral particles - how do they maintaintain their neutrality.
     
  5. Jan 27, 2015 #4

    Drakkith

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    I'm sorry but this is just wrong.

    They don't. Electrons have a negative charge, protons have a positive charge, and neutrons are electrically neutral. You're replying to a bad answer.

    The electrons that flow into the cathode are used in the chemical reaction between the cathode and the electrolyte. They are indeed 'lost' from the cathode in this reaction.
     
  6. Jan 27, 2015 #5

    Bystander

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    "Cathode" is the term for any electron source. "Electrodes" in a voltaic cell can be "cathodes" when one considers their function within the cell as electron sources for reactants within the cell, and as "anodes" when one considers their function outside the cell as electron sinks for an electrical circuit.
     
  7. Jan 27, 2015 #6

    Drakkith

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    Indeed. A cathode is generally the electrode that conventional current leaves. Conventional current is a flow of positive charges, which is the same as negative charges flowing the opposite direction. So the cathode is just the electrode that electrons flow into. This refers to the external circuit of course. For a battery, the 'internal circuit', consisting of the two electrodes and electrolyte, this is opposite. Electrons leave the cathode and flow into the electrolyte.
     
  8. Jan 27, 2015 #7
    Can you please tell me why cathode is at high potential in galvanic cell?As in galvanic cell electrons naturally(spontaneously) flow from anode to cathode ,cathode must be at higher potential because electrons always move from lower to higher potential.But how cathode is at higher potential?How anything can be at higher potential?
     
  9. Jan 27, 2015 #8

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    Very quick question: has there been any explicit statement in class regarding electrode name convention? There are at least two, European, and American, and they have been a source of endless confusion over the past one or two centuries.

    Same question: which convention?
     
  10. Jan 27, 2015 #9
    We have been told that at anode oxidation takes place and at cathode reduction takes place.I don't know whether it is European and American convention.Please tell me why cathode is at high potential in galvanic cell?How anything can be at higher potential?
     
  11. Jan 27, 2015 #10

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    I'll call that American. It's an electron source and reduces oxidized species which reach it.
    Without context, "higher potential" is meaningless; the discussion in your text or lecture notes has to be comparing it to something, and without knowing what that "something" is, it's tough to really answer your question.
     
  12. Jan 27, 2015 #11
    Higher potential than anode.
     
  13. Jan 27, 2015 #12

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    This may be more in reference to the electrons themselves. Electrons at/on the cathode have a higher potential energy than exists for oxidized species approaching the cathode, or at the anode once they've been transported through the cell.
     
  14. Jan 27, 2015 #13
    You mean it depends on material of cathode or anode?If one electrode is made up of copper and the other one is made up of zinc,electrons of zinc would be at lower potential than electrons of copper?Right?If yes.then it implies that reduction or oxidation potential is all about electrons of particular material/element.
     
  15. Jan 27, 2015 #14

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    Yes.
    Copper ions oxidize zinc, or zinc reduces copper ions.
    Yes.
     
  16. Jan 28, 2015 #15
    Sir,last question
    If any element's electron has greater oxidation potential does it mean it has lower potential than the electrons of cathode?But why only reduction potential is considered as potential not oxidation potential?Because if we consider oxidation potential the anode would be at higher potential.
     
  17. Jan 28, 2015 #16

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    This is another of those "arbitrary choices/conventions." Whether it's regarded as one or the other, it's the same reaction. We're just looking at which direction we're going to consider. If we say "oxidation," it means we're going to look at how easily every reaction proceeds as an oxidation when comparing them. If we say "reduction," we're comparing every reaction as a reduction.
     
  18. Jan 28, 2015 #17
    Let us take oxidation potential as potential .Then anode (at which oxidation takes place)should be at higher potential than cathode.As electrons move towards higher potential ,electrons should move from cathode to anode,but it is really not the case.So how it's our choice whether we take oxidation or reduction potential as potential of electron?
     
  19. Feb 1, 2015 #18
    How does a salt bridge complete circuit?As no electrons flow within salt bridge.
     
  20. Feb 1, 2015 #19

    Borek

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    Current is a movement of charge. Electrons are not the only charged objects.
     
  21. Feb 1, 2015 #20
    So ,you mean ions ?Ions are responsible for completing the circuit via salt bridge?
     
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