Reactions of metals with steam
Magnesium reacts very slowly with water. However, it reacts vigorously with steam:
magnesium + steam 鈫 magnesium oxide + hydrogen
Mg(s) + H2O(g) 鈫 MgO(s) + H2(g)
Metals which react with steam form the solid metal oxide and hydrogen gas.
In general, the more reactive the metal, the more rapid the reaction. Aluminium is unusual, because it is a reactive metal that does not react with water. Its surface forms a protective layer of aluminium oxide that keeps water away from the metal below.
The apparatus used to react a metal with steam and collect the gas produced is shown below.
The damp mineral wool is heated to generate steam.