Question

Give the conditions under which magnesium reacts rapidly with water. Write an equation to represent this reaction.

Answer 1

Magnesium reacts very slowly with cold water. The reaction is hampered by the formation of magnesium hydroxide which coats the surface of the magnesium metal. The magnesium hydroxide coating prevents further reaction of the magnesium metal and the cold water.
Magnesium however reacts rapidly with steam. In this reaction magnesium oxide instead of magnesium hydroxide is formed alongside hydrogen.
The reaction:
   
            Mg  +  H2O --------->  MgO  + H2
             (s)          (steam)          (s)      (g)