A particular reaction has a negative value for the free energy change. Then at ordinary temperaturea) It has a large -ve value for the entropy change b) It has a large +ve value for enthalpy change c) It has small +ve value for enthalpy change d) It has a +ve value for the entropy change and a -ve value for the enthalpy change Correct answer is option 'D'. Can you explain this answer?

Question

A particular reaction has a negative value for the free energy change. Then at ordinary temperaturea)                                  It has a large -ve value for the entropy change                               b)                                  It has a large +ve value for enthalpy change                               c)                                  It has small +ve value for enthalpy change                               d)                                  It has a +ve value for the entropy change and a -ve value for the enthalpy change                               Correct answer is option 'D'. Can you explain this answer?

Answer

Explanation:

Negative value for free energy change indicates that the reaction is spontaneous and releases energy. At ordinary temperature, the following possibilities can be considered:

Entropy Change:
- If the reaction has a large negative value for the entropy change, it means that the reactants are more ordered than the products, which is not favored. Therefore, the reaction may not occur spontaneously.
- If the reaction has a small negative value for the entropy change, it means that the reactants and products are equally ordered, which is favorable. Therefore, the reaction may occur spontaneously.

Enthalpy Change:
- If the reaction has a large positive value for the enthalpy change, it means that the reactants are more stable than the products, which is not favored. Therefore, the reaction may not occur spontaneously.
- If the reaction has a small positive value for the enthalpy change, it means that the reactants and products are equally stable, which is favorable. Therefore, the reaction may occur spontaneously.
- If the reaction has a negative value for the enthalpy change, it means that the products are more stable than the reactants, which is favorable. Therefore, the reaction may occur spontaneously.

Conclusion:
Option D is the correct answer because a negative value for the free energy change indicates that the reaction is spontaneous and releases energy, which means that the products are more stable than the reactants (negative enthalpy change) and the reaction leads to an increase in disorder (positive entropy change).

Answer

ΔG=ΔH−TΔS can be negative at ordinary temperature T if ΔH is −ve and ΔS is +ve since it gives overall value of ΔG as negative.

Answer

Acc to formula ∆G= ∆H - T∆S option d is most appropriate answer

Answer

First of all language of this question was not clear
so they were saying that at normal temperature gibbs free energy is negative and asking the conditions which satisfy negative value of gibbs free energy at any case.
∆G=H-T∆S
so to make above equation negative we need postive entropy and negative enthalpy of reaction
thus(d) is correct

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