1. 1  an implement, such as a hammer, saw, or spade, that is used by hand. 2  a power-driven instrument; machine tool. ( 3 in combination): a toolkit.
The standard enthalpy of combustion is the enthalpy change when one mole of a reactant completely burns in excess oxygen under standard thermodynamic conditions (although experimental values are usually obtained under different conditions and subsequently adjusted).he standard enthalpy of combustion is the enthalpy change when one mole of a reactant completely burns in excess oxygen under standard thermodynamic conditions (although experimental values are usually obtained under different conditions and subsequently adjusted).
Here, we discuss about enthalpy of system and the change in enthalpy of system. The enthalpy of system is similar to the internal energy of system which is the total energy of system but it is equal to amount of absorbed or released hat of system at constant pressure.he Heat energy associated with combustion is called enthalpy of combustion. The reaction is considered only in the presence of oxygen. When one mole of a substance burns completely in the presence of oxygen, then heat change is called enthalpy of combustion.