Heats of reactions

The heat of fusion of a substance (= -ΔH_fusion= -fusion enthalpy) is the quantity of heat transferred to the surroundings during the fusion (passage from solid to liquid) at constant pressure of one mole.

The heat of vaporization of a substance (= -ΔH_vaporisation= -vaporisation enthalpy) is the quantity of heat transferred to the surroundings during the vaporization (passage from liquid to gas) at constant pressure of one mole of this substance.

The heat of condensation of a substance (= -ΔH_condensation = -condensation enthalpy) is the quantity of heat transferred to the surroundings during the condensation (passage from gas to liquid) at constant pressure of one mole of this substance.

The heat of sublimation of a substance (= -ΔH_sublimation= -sublimation enthalpy) is the quantity of heat transferred to the surroundings during the sublimation (passage from solid to gas) at constant pressure of one mole of this substance.

The energy of (the first) ionization of an element (= ΔH_ionisation= -standard enthalpy of ionization) is the quantity of heat received by one mole of atoms of this element to remove one electron from each of its atoms.

The (first) electron affinity of an element (= ΔH_{electron affinity} ) is the quantity of heat received by one mole of atoms of this element to give one electron to each of its atoms.

The reticular energy of ionic substances (= ΔH_reticular= -standard reticular enthalpy) is the quantity of heat received by one mole of this substance to form the lattice.

The heat of hydratation of ions (= -ΔH_hydratation= -hydratation enthalpy) is the quantity of heat transferred to the surroundings by one mole of these ions during the hyratation (passage from gaseous ion to hydrated ion).