Ethanol 1C2H5OH2 melts at -114 °C and boils at 78 °C.The enthalpy of fusion of ethanol is 5.02 kJ>mol, and itsenthalpy of vaporization is 38.56 kJ>mol. The specific heatsof solid and liquid ethanol are 0.97 and 2.3 J>g@K, respectively.(a) How much heat is required to convert 42.0 g ofethanol at 35 °C to the vapor phase at 78 °C? (b) How muchheat is required to convert the same amount of ethanol at-155 °C to the vapor phase at 78 °C?
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.
Ethanol 1C2H5OH2 melts at -114 °C and boils at 78 °C.
The enthalpy of fusion of ethanol is 5.02 kJ>mol, and its
enthalpy of vaporization is 38.56 kJ>mol. The specific heats
of solid and liquid ethanol are 0.97 and 2.3 J>g@K, respectively.
(a) How much heat is required to convert 42.0 g of
ethanol at 35 °C to the vapor phase at 78 °C? (b) How much
heat is required to convert the same amount of ethanol at
-155 °C to the vapor phase at 78 °C?
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