DF1 enthalpy changes 

$Standard enthalpy change for a reaction$$-$ the enthalpy change when molar quantities of reactants, as stated in the equation, react together under standard conditions

$Standard enthalpy change of combustion$- the enthalpy change that occurs when one mole of a substance is burnt completely in oxygen under standard conditions

$Enthalpy change for formation$- the enthalpy change that occurs when one mole of a substance is formed from its elements under standard conditions

$Enthalpy change of neutralisation-$ the enthalpy change when one mole of water is created from the reaction between an acid and an alkali in aqueous solutions under standard conditions.