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).
Top 10 amazing movie makeup transformations. Enthalpy is the heat energy exchange that takes place during chemical reactions. It has the symbol H and is measured in kJ/mol, or kilojoules per mole. The energy exchanged with the surrounding environment at constant pressure is called the enthalpy change of a reaction. To measure the change, standard conditions are used, including a pressure of 1 atmosphere and a temperature of 298 Kelvin (77Â°F or 25Â°C).