Define the term enthalpy of combustion. What is its signification ?

Explanation

Enthalpy of combustion is defined as the change in enthalpy, when one mole of a substance is completelt burnt in excess of oxygen.
For example, enthalpy of combustion of carbon is given by the following equation :
`C(s) + O_(2) to CO_(2) (g), Delta H = - 393.5 kj`
Signiicance : Enthalpy of combustion is used to decide the quality of fuel. If the fuel has large heat of combustion. then it will of a good quality fuel and vice versa.