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Fuel Cell Inspiration
As soon as I read the name of the kit, I was
intrigued. Apparently, magnesium + saltwater + air = electricity. This kit also
has to be one of the easiest to put together; it is literally almost a
"snap." This is a great classroom project for learning about
different fuel cell technologies and the young scientists can even test
different ratios of salt to water to see which mixture yields the greatest
efficiency. 
Salt Water Fuel Cell Concept
A fuel cell is an electrochemical
cell that converts energy from a fuel into electrical energy. Fuel cells can
operate continuously as long as the necessary reactant and oxidant flows are
maintained. In this cell, magnesium is the anode, the porous carbon sheet (air)
is the cathode, and saltwater is the electrolyte. This is known as an
air-depolarizing type of battery. During chemical reactions, alkaline earth
metals (magnesium) lose two electrons. Elementary halogens such as chlorine,
which can be found in ordinary table salt (NaCl), are also relatively reactive.
Unlike the alkaline earth metals, the halogens tend to gain electrons. These
are known as oxidizing agents because they remove electrons from other
elements.
The saltwater slowly dissolves the magnesium sheet to produce hydrogen ions
that migrate to the carbon cathode, thus creating an electrical current. The
carbon surface would almost immediately become blocked, or polarized, by the
hydrogen except that the carbon is porous. Air diffuses down through the carbon
and yields oxygen that combines with the hydrogen to form water, permitting the
electrical effect to continue.
