Enthalpy
of combustion
Enthalpy of neutralization
Enthalpy of reaction
Free enthalpy
Free enthalpy of a reaction
When a chemical system undergoes combustion, the enthalpy of combustion is measured by the heat exchanged between the system and its environment; such combustion is carried out under constant pressure.
Enthalpy (or
energy)
of neutralization
When a chemical system undergoes neutralization, the enthalpy of neutralization is measured by the heat exchanged between the system and its environment.
When a system undergoes a chemical reaction, the enthalpy of reaction is the difference between the enthalpy of the products of the reaction and the enthalpy of the reagents necessary to their production.
It is equal to the heat exchanged between the system and its environment, when the reaction is carried out at constant pressure.
Free enthalpy
(called Gibbs function and denoted G )
State function of the enthalpy H of a system, defined by equation
G = H - T S
where S is the entropy of the system and T is the temperature on the Kelvin scale.
The variation of free enthalpy of a system due to a chemical reaction.
It is measured by the difference between the free enthalpy of the products of the reaction and the free enthalpy of the reagents necessary to their production.