Question

The feasibility of a chemical reaction can be explained based on $$\mathrm{\Delta }H$$ , $$\mathrm{\Delta }S$$ and $$\mathrm{\Delta }G$$ . For $$2O_{3(g)}\to 3O_{2(g)}$$ if the reaction is feasible then:
(this question has multiple correct answers)
A. $$\mathrm{\Delta }S$$ = +ve
B. $$\mathrm{\Delta }G$$ = +ve
C. $$\mathrm{\Delta }H$$ = -ve
D. $$\mathrm{\Delta }G$$ = -ve

Answer 1

Hint: $$\mathrm{\Delta }S$$ , $$\mathrm{\Delta }H$$ and $$\mathrm{\Delta }G$$ are known as the change in entropy, the change in enthalpy and the change in Gibbs energy respectively. All these quantities are inter - related and are dependent on one another. The mathematical relation between these quantities can be represented as:
  $$\mathrm{\Delta }G=\mathrm{\Delta }H-T\mathrm{\Delta }S$$ , where T is the temperature of the system.

Complete step by step answer:
Before we move forward with the solution of this question, let us understand a few important basic concepts.
 $$\mathrm{\Delta }S$$ : $$\mathrm{\Delta }S$$ is known as the change in the entropy of a system. Entropy can be understood as the degree of randomness of a system. This randomness of a system can be better understood as the energy of the system that is not available for doing work. There is a direct relation between the entropy of a system and the number of particles present in the system. The degree of randomness of a system increases if the number of particles within the system increases.
 $$\mathrm{\Delta }H$$ : $$\mathrm{\Delta }H$$ is the change in the enthalpy of the reaction. It accounts for the total change in energy that is observed in the reaction.
 $$\mathrm{\Delta }G$$ : $$\mathrm{\Delta }G$$ is known as the Gibbs free energy. The value of the Gibbs free energy represents the degree of spontaneity of the reaction. To explain it in simpler terms, $$\mathrm{\Delta }G$$ tells us whether or not a given reaction will proceed on its own without any external stimulus. If the value of $$\mathrm{\Delta }G$$ is negative for a given reaction, then the reaction is said to be spontaneous.
Now coming back to the question, looking at the reaction, we can say that the number of particles in the system has increased from 2 to 3. Hence the entropy of the system has increased. Also, ozone is less stable to oxygen. Hence the conversion of ozone to oxygen is a spontaneous reaction. This spontaneous conversion results in the breaking of the $$$$bonds which in turn releases energy.
From the above deductions we can say that $$\mathrm{\Delta }S$$ = +ve, $$\mathrm{\Delta }H$$ = -ve and $$\mathrm{\Delta }G$$ = -ve

Hence, Options A, C and D are the correct options.

Note:
Gibbs free energy combines enthalpy and entropy into a single value. Gibbs free energy is the energy associated with a chemical reaction that can do useful work. It equals the enthalpy minus the product of the temperature and entropy of the system.