Decomposition reaction: occurs when energy in the form of heat, light, electricity, or mechanical shock is supplied. A compound may decompose to form simpler compounds and/or elements. The general form of a decomposition reaction is
compound --> two or more substances
There are six general types of decomposition reactions
a. Some oxy-acids, when heated, decompose to form water and the nonmetal oxide.
H2CO3 --> H2O + CO2
b. Some metallic hydroxides, when heated, decompose to form the metal oxide and water.
Ca(OH)2 --> CaO + H2O
c. Some metallic carbonates, when heated, decompose to form the metal oxide and carbon dioxide.
Li2CO3 --> Li2O + CO2
d. Some metallic chlorates, when heated, decompose to form metal chloride and oxygen gas.
2KClO3 --> 2KCl + 3O2
e. Most metallic oxides are stable, but a few decompose when heated to form the metal and oxygen gas.
2HgO --> 2Hg +O2
f. Some compounds can be decomposed by electricity into their elements.
2NaCl --> 2Na + Cl2