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).
Also, the standard molar enthalpy of combustion of a substance is defined as the amount of heat liberated when one mole of that substance is burned completely in excess of air (so that complete oxidation is ensured).