Potato battery, how does it work?

[christian0710]

Hi just made a potato battery, using a cupper coin and zink nails (not connected in any way, just pit in a nail and 3 inches appart a penny), I was just wondering what is the chemistry/physics theory here?

Potatoes contain phosphoric acid
H3PO4

Is it the acid in potatoes that oxidize the 2 metals? or id it the standard electrode potential?

Electrode potential for Zn
Zn(+2) + 2e ---> Zn(s) = -0,76 V (so it want's to be oxidized and should reduce Cu (+2) to Cu (s) because Cupper has a positive electrode potential.

But does the acid oxidize both metals in the first place?

 

[jtbell]

Hmmm... can a potato battery produce enough "juice" to light up a pickle?

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/pickle.html

 

[Alkim]

Using a potato is just one of infinity of choices. Any electrolyte should work given it does not pasivate the surface of the metals.