The molar enthalpy of vaporization of a liquid at its normal boiling point is 39.16 kJ mol-1. When a liquid boils some part of the enthalpy is used in converting the liquid into vapor. The remaining is used in expansion work of the vapor against the external pressure. Calculate what percentage of the enthalpy of vaporization of this liquid is used for the expansion work. Assume that the vapor behaves ideally and that the molar volume of the liquid can be neglected when compared to the molar volume of the vapor. At the normal boiling point of liquid 466.6K, the pressure is 1.00 atm (exactly) by definition.
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
The molar enthalpy of vaporization of a liquid at its normal boiling point is 39.16 kJ mol-1. When a liquid boils some part of the enthalpy is used in converting the liquid into vapor. The remaining is used in expansion work of the vapor against the external pressure. Calculate what percentage of the enthalpy of vaporization of this liquid is used for the expansion work. Assume that the vapor behaves ideally and that the molar volume of the liquid can be neglected when compared to the molar volume of the vapor. At the normal boiling point of liquid 466.6K, the pressure is 1.00 atm (exactly) by definition.
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