Thermochemistry

Thermochemistry

branch of chemistry that studies the heat changes that occur during chemical reactions.

Heat of reaction

(symbol Q, unit kJ/mol) the amount of heat released or absorbed during a chemical reaction (basically the difference in enthalpy between the products and reactants in a chemical reaction)

Enthalpy

(symbol H, unit kJ/mol) the total heat content of substance

Change of enthalpy

(symbol ΔH, unit kJ/mol) the difference in enthalpy between the products and reactants in a chemical reaction.

exothermic reaction

A reaction that releases heat to the surroundings (ΔH is negative). Surrounding gets hotter

endothermic reaction

A reaction that absorbs heat from the surroundings (ΔH is positive). Surrounding gets cooler