Reactions in Galvanic Cells

[Wizard]

Hey guys,

A question says "a galvanic cell has one half cell with Copper metal dipped in 1M Copper Sulfate, and one half cell containing Zinc metal dipped in 1M Zinc Sulfate. A salt bridge and an external circuit are present" Zinc is obviously the best reductant, so therefore is oxidised at the anode. I also thought that at the cathode, Copper ions would be reduced to become Copper. However, it seems that because the aqueous solutions which the metals are dipped in contain water, at the cathode, water is actually reduced. (Oxygen + Water + 4e-  -->  4OH-) Is this right? 

[Collin Li]

No... that is the Daniell Cell, a well documented cell, and the reaction is supposed to be the reduction of copper ions, rather than water...

[Wizard]

Lol, yeah, thats what I think. I dont know why the answers say that hydroxide ions are produced though, it says that water is a better oxidant than Copper ions when water reacts with Oxygen. I think the problem though is the relative concentrations, which do not follow the standard conditions used on the Electrochemical Series. The answer on the sheet is wrong.

Thanks Coblin!

[Glockmeister]

But there's no oxygen in the cell itself (there's only water unless you bubble oxygen into the solution) so I can't see how that cathode reaction could possibily occur.