Which one of the following reactions cannot proceed spontaneously as written at any temperature? Assume that ΔH°rxn does not depend on temperature. Only 1 option is the correct answer. A. 2Cl2O(g) → 2Cl2(g) + O2(g) ΔH°rxn = –151 kJ B. 3O2(g) → 2O3(g) ΔH°rxn = +284 kJ C. COCl2(g) → CO(g) + Cl2(g) ΔH°rxn = +112 kJ D. 2C(s) + 2S(s) + O2(g) → 2COS(g) ΔH°rxn = –137 kJ E. N2O4(g) → 2NO2(g) ΔH°rxn = +171 kJ
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.
Which one of the following reactions cannot proceed spontaneously as written at any temperature? Assume that ΔH°rxn does not depend on temperature. Only 1 option is the correct answer.
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A.
2Cl2O(g) → 2Cl2(g) + O2(g) ΔH°rxn = –151 kJ
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B.
3O2(g) → 2O3(g) ΔH°rxn = +284 kJ
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C.
COCl2(g) → CO(g) + Cl2(g) ΔH°rxn = +112 kJ
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D.
2C(s) + 2S(s) + O2(g) → 2COS(g) ΔH°rxn = –137 kJ
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E.
N2O4(g) → 2NO2(g) ΔH°rxn = +171 kJ
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