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) Also, since the heat evolved at constant pressure is the enthalpy change, â¬ q rev = p Î´ H, the entropy change for a phase transition becomes â¬ Î´ S = Î´ HT. (2) Example Determine the standard molar entropy for the following phase transition occurring at 1 bar pressure and 100Â°C, 2â¬ HO (â) â H 2 O (g) .(3) This phase transition is known as vaporization, and the standard molar enthalpy of vaporization, vapâ¬ Î´ H ! , for water may be found in the literature as 44.0 kJ/mol.The standard molar entropy of vaporization is therefore â¬ Î´ S vap ! = Î´ H vap ! T vap = 44.0Ã10 3 J/mol373 KÎ´ S vap ! = 118 Jmol â1 K â1.1) Also, since the heat evolved at constant pressure is the enthalpy change, â¬ q rev = p Î´ H, the entropy change for a phase transition becomes â¬ Î´ S = Î´ HT. (2) Example Determine the standard molar entropy for the following phase transition occurring at 1 bar pressure and 100Â°C, 2â¬ HO (â) â H 2 O (g) .