A thermochemical equation is a balanced stoichiometric chemical equation that represents the energy changes from a system to its surroundings. One such equation involves the enthalpy change, which is denoted with ΔH. In variable form, a thermochemical equation would appear similar to the following:
:A + B → C
:ΔH = (±) #
{A, B, C} are the usual agents of a chemical equation with coefficients and “(±) #” is a positive or negative numerical value, which generally has units of kJ/J. Another equation may include the symbol E to denote energy; E<nowiki/>'s position determines whether the reaction is considered endothermic or exothermic.
A + E → C (endothermic, where E would be considered a positive magnitude) 
A → C + E (exothermic, where E would be considered a negative magnitude)