Concept explainers
If a reaction is exergonic, then which of these statements is true?
a. The products have lower Gibbs free energy than the reactants.
b. Energy must be added for the reaction to proceed.
c. The products have lower entropy (are more ordered) than the reactants.
d. The reaction always occurs quickly.
Introduction:
The Gibbs free energy is a thermodynamic equation, where it is enthalpy (of a system or process) minus the product of the entropy and the absolute temperature. It is used to determine the spontaneity of the reaction.
Answer to Problem 1TYK
Correct answer:
The Gibbs free energy of the products is lower than that of the reactants.
Explanation of Solution
Explanation/Justification for the correct answer:
Option (a) is given as lower Gibbs free energy of products as compared to the reactants. In the case of exergonic reactions, the energy is always released. In this case, the reactants on interaction lose energy, so the energy of the products is lower than that of the reactants. The Gibbs free energy of the reaction is always negative in this case. Hence, option (a) is correct.
Explanation for incorrect answers:
Option (b) is given as need of energy for the reaction to proceed. There is no requirement for the energy to be added in the reaction, as these reactions do not require energy. So, it is a wrong answer.
Option (c) is given as that the products have lower entropy (are more ordered) than the reactants. The entropy of the products is increased in the case of exergonic reactions. The exergonic reactions are spontaneous and the spontaneity is favored toward the increase in entropy. Thus, the entropy of the products increases. So, it is a wrong answer.
Option (d) is given as that the reaction always occurs quickly. The rate of the reaction depends on many physical factors; hence, the reaction may be slow or quick depending on the external conditions. So, it is a wrong answer.
In an exergonic reaction, the products have lower Gibbs free energy than the reactants.
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