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The above is a picture of Galvanic cell. Zinc anode is placed in Zinc sulfate solution so we have ions as Zn2+ and SO42-. On the cathode side we have the same situation we have Cu2+ and SO42-. My question is why the zinc rod is getting converted into zinc ions and copper ions are getting converted into atoms and get deposited on copper rod. Why is electron flowing from anode to cathode?

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The semi-reaction of reduction for Zn is :

$Zn^{2+} +2e^- \rightarrow Zn \quad E^\circ =-0.763$

The semi-reaction of reduction for Cu is :

$Cu^{2+} +2e^- \rightarrow Cu \quad E^\circ= 0.337$

The standard redox potential for Cu is more positive thus it is reduced and Zn is oxidized. Electrons flow from a negative to a positive potential. They flow towards the cathode because their potential V, at the anode is more negative, thus they have an higher potential energy: $U_e = V*e$

note that $e$ the charge of the electron is negative as well as V.

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  • $\begingroup$ Thank you so much. Your answer is very nice. $\endgroup$ Feb 24, 2019 at 3:46
  • $\begingroup$ I want to ask that if I’m right in saying this:- the ionisation potential (that is electric potential created when the atom gets converted to ion) of Zinc ion is 9.39 and copper ion is 7.72. Since there is a potential difference therefore electrons would flow from higher potential to lower potential. $\endgroup$ Feb 24, 2019 at 3:48

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