ΔH° and ΔH

Definition

ΔH represents enthalpy change during a reaction while ΔH° represents standard enthalpy change (at 1 atm pressure and specified temperature).

Related terms

Enthalpy (H): The heat content of a system at constant pressure.

Exothermic Process: A process that releases heat causing an increase in temperature of its surroundings; has negative ΔH value.

Endothermic Process: A process that absorbs heat causing a decrease in temperature of its surroundings; has positive ΔH value.