exothermicity

noun

1. (uncountable, usually)The quality or state of being exothermic.

   “The second step is substantially exothermic and fast; the overall exothermicity ensures that there is no tendency for the reaction to reverse.”

2. (countable, usually)The release of heat during an exothermic reaction.

   “Because of the unusual methylene substitution selectivities, the exothermicities of the different methylene substitution reactions were calculated from estimated heats of formation of the reactants and heats of formation of the products.”