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Half cells

Do the electrons alweays flow from more reactive metal to less reactive metal or is it determined by the electrode potential of each half cells?

thanks

Reply 1

Kallisto

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The half cells consist of two eletcrodes, namely zinc anode and a copper cathode. In a Galvanic cell the one electrode is an oxidazing agent, while the other one is a reducing agent. The copper cathode is more noble than the zinc anode, thats why the copper cathode tends to reduce, while the zinc anode tends to oxidate (the lesser noble a metal is the higher the oxidation potential of a metal). And so more electrons goes to the zinc anode, while lesser electrons goes to the copper cathode. Thus the zinc anode has an surplus of electrons and the copper cathode has an electron deficiency. That is the reason why the electrodes form polarities, if the electrodes apply a voltage. So the zinc anode is negative, while the copper cathode is positive.

(edited 10 years ago)

Reply 2

Borek

Original post by Zenarthra

Do the electrons alweays flow from more reactive metal to less reactive metal or is it determined by the electrode potential of each half cells?

thanks

It is a matter of electrode potentials. If the difference between standard potentials is not too high, you can reverse the current by selecting right concentrations. That's where the Nernst equation comes handy.