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I'm trying to understand conduction of electricity in a solution. Is it correct that anions give their extra electrons to the anode, which transfers the electrons to the cathode, where the cations receive them?

In addition - if my understanding is correct, then very soon all the ions will neutralize (the cations will gain the electrons, the anions will lose theirs) and the flow of electrons will stop?

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  • $\begingroup$ What part seems to be giving you trouble on this? I mean, a textbook should give you the information about this, so what part is missing for you? $\endgroup$
    – Kyle Kanos
    Commented Dec 18, 2014 at 20:55
  • $\begingroup$ I think this question should migrate to Chemistry SE, but I will put up a short answer that I am happy to have deleted. - sorry not sure how to recommend migration $\endgroup$
    – tom
    Commented Dec 18, 2014 at 21:25
  • $\begingroup$ From chem stack exchange chemistry.stackexchange.com/questions/14123/… $\endgroup$
    – Paul
    Commented Dec 19, 2014 at 3:38

2 Answers 2

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Two points

1) mostly it will take a long time for all the ions to neutralize

2) it is not always the ions that neutralize.... for example, if you have sodium hydroxide , Na$^+$OH$^-$ then the reactions at the electrodes are $$2H^+ + 2e^- \rightarrow H_2$$ and $$4OH^- \rightarrow 2H_2O + O_2 +4e^-$$ and the $H^+$ and $OH^-$ ions used up are replenished by the water $H_2O$ - so in this case the electrolysis will keep running until the water is used up.

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You assert:

Is it correct that anions give their extra electrons to the anode, which transfers the electrons to the cathode, where the cations receive them?

...which is correct. You seem to be concerned that it is not an eternal circuit when you then note:

In addition - if my understanding is correct, then very soon all the ions will neutralize (the cations will gain the electrons, the anions will lose theirs) and the flow of electrons will stop?

which is also factual. There is no problem with the circuit running out of ions if not replenished, since the purpose of electrolysis is either:

  • to produce another substance by applying electrodes to a solution, such as generating hydrogen (and oxygen) from water using electricity;
  • or to produce electrical energy by combining two substances such as hydrogen and oxygen in what is known as a galvanic cell.
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