Valuable money

Volta's pile (or Galvani's pile) is a device which is more a chemical one than physical one: the electric charge is transported by chemical reactions: reduction of ions (in the physical terminology "electron attachment) or oxidation ("ionization" or electron detachment).

For example, in the Zn/Cu pile zinc atoms move to the solution and copper ions deposit on the anode. A so-called electrochemical potential is the characteristic feature of a given metal, or more precisely, of a given ion in a given solution. For example, reduction of the single valence copper ion Cu⁺ + e -> Cu shows the electrochemical potential of +0,521 V and the bivalence ion Cu²⁺ + 2e -> Cu shows a potential of +0,342 V. The electrochemical potential of the same reaction but in the solution of Hg is slightly different, +0,345 V. This potential depends also on the crystallographic phase, for example the potential of forming the phosphine gas (poisonous, produced for example during the organic garbage fermentation) P + 3H⁺ + 3e -> PH₃ is -0.11V for red phosphor and -0,06V for the white one.

To make Volta's pile you need coins made of two different metals and a piece of wet paper (better if they are submerged in a salt solution). Two pieces of different metal connected with a wire and inserted into a lemon, a vase with flowers, into a tomato or potato work equally well; see the IQ meter, lemon battery or Volta's tongue. So try your change, what is the real value of your money (at least as an electric pile).