enthalpy change definition

Question 1

define enthalpy change of formation

Answer 1

enthalpy change when one mole compound is formed from it’s element under standard conditions

Question 2

define enthalpy change of reaction

Answer 2

enthalpy change when the amounts of reactants shown in the stoichiometric equation reacts to give products under standard conditions

Question 3

define enthalpy change of combustion

Answer 3

the enthalpy change when one mole of a substance is burnt in excess oxygen under standard conditions