I won this "toy" at a science fair... Now I have to make a short presentation about it in school. On the package description they describe its energy source as "fuel cell"... It consists out of a metal plate(magnesium), a black metal plate with a black coating and a paper-cotton-like isolator which is between those plates. Through putting salt water on the isolator, there's a voltage difference of 1.76V between the black and the magnesium plate. After a couple of seconds on load the voltage stays constant at 1.31V. My theory is that it's only a simple battery, because there's no continious source of fuel which should be required for naming it fuel cell (according to wikipedia).
Is my thought right?
My idea about the black coat is, that it is a rubberd graphite or "coal" cathode, rubberd because coal or graphite would fall apart quickly. It is described as air-cathode in the package description. My idea is that the black coal or graphite coat is used to provide a larger amount of air to the reaction...
The magnesium plate gets damaged through this reaction, the black thing not.
Which material is the black coat?
and what is the full reaction?