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).
1 By definition, the heat of combustion is minus the enthalpy change for the combustion reaction, ie, -Î´ reaction H. 2  By definition, the heat of combustion is a positive value. 3  Heat of Combustion can be measured experimentally.