posted by Cameron .
When relatively small amounts of magnesium burn, the fires are extinguished using commercially available dry powder.
a)Why might this fire rekindle days later as someone tries to remove the residue with water?
b)What chemical process is involved here?
Water reacts with Mg to produce H2 gas. This is an exothermic reaction PLUS H2 gas is explosive
Mg + H2O ==> H2 + MgO