In chemistry and thermodynamics, the enthalpy of neutralization (ΔHn) is the change in enthalpy that occurs when one equivalent of an acid and a base undergo a neutralization reaction to form water and a salt.
When a reaction is carried out under standard conditions at the temperature of 298 K (25 degrees Celsius) and 1 atm of pressure and one mole of water is formed, the heat released by the reaction is called the standard enthalpy of neutralization (ΔHn⊖).
From this, the standard enthalpy change (∆H) is obtained by division with the amount of substance (in moles) involved.
When a strong acid, HA, reacts with a strong base, BOH, the reaction that occurs is as the acid and the base are fully dissociated and neither the cation B+ nor the anion A− are involved in the neutralization reaction.
[1] In the absence of any added mineral acid or alkali, some heat is required for complete dissociation.