sentence: Exothermic reactions give out heat.
sentences_before: Endothermic reactions take in heat.
sentences_after: Thermochemistry combines the concepts of thermodynamics with the idea of energy in the form of chemical bonds. It includes calculations of such quantities as heat capacity, heat of combustion, heat of formation, enthalpy, entropy, free energy, and calories.
concept_name: exothermic reaction
headings: Thermochemistry
categories: Physical chemistry