An compact equation representing a chemical reaction that describes both the stoichiometry and the energetics of the reaction. For example, the thermochemical equation CH4(g) + 2 O2(g) CO2(g) + 2 H2O(g), H = -2220 kJ means "When one mole of gaseous CH4 is burned in two moles of oxygen gas, one mole of CO2 gas and 2 moles of steam are produced, and 2220 kilojoules of heat are released."