Reaction of calcium hydride (CaH2) and water, evolution of hydrogen:
CaH2(s) + 2H2O(l) → Ca(OH)2(aq, s) + 2H2(g) (1)
or in ionic form:
CaH2(s) + 2H2O(l) → Ca2+(aq) + 2OH–(aq) + 2H2(g)
Combustion of hydrogen in air (in air oxygen):
2H2(g) + O2(g) → 2H2O(g)
(1)-Calcium hydroxide is only partially insoluble in water.
Caution, hydrogen is a highly flammable gas!
1) HYDROGEN: “Hydrogen from metal and acid”
2) HYDROGEN: “Hydrogen from metal and alkali”