role in the ripening of certain fruits and vegetables. It is sometimes supplemented under controlled conditions at produce—processing facilities but is also produced naturally by many fruit-bearing plants. Although the actual process by which plants produce ethylene is a complex one, imagine that it is produced by the simple breakdown of glucose according to the equation: C6H12O6 (s) à 3 C2H4 (g) + 3 O2 (g) Given S°= 212.1 J/molK, DG°= -910.56 kJ/mol and DH°= -1274.5 kJ/mol for C6H12O6 (s). a.) Determine the sign of DS° for the reaction.
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.
Ethylene (C2H4) plays an important role in the ripening of certain fruits and vegetables. It is sometimes supplemented under controlled conditions at produce—processing facilities but is also produced naturally by many fruit-bearing plants. Although the actual process by which plants produce ethylene is a complex one, imagine that it is produced by the simple breakdown of glucose according to the equation:
C6H12O6 (s) à 3 C2H4 (g) + 3 O2 (g)
Given S°= 212.1 J/molK, DG°= -910.56 kJ/mol and DH°= -1274.5 kJ/mol for C6H12O6 (s).
a.) Determine the sign of DS° for the reaction.
b.) Calculate DS° for the reaction.
c.) Using the tabulated DG° values in the appendix, calculate DG° for the reaction.
d.) Above what temperature (in °C) is the reaction spontaneous? Hint: you will first have to calculate DH° using tabulated values.
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