What will be the result of a reaction if its enthalpy change is positive, its entropy change is negative and Gibbs free energy is positive?

A. Spontaneous, if the temperature is high
B. Nonspontaneous, if the temperature is low
C. Always spontaneous
D. Never spontaneous

I think the answer is d or b.

To determine the spontaneity of a reaction based on its enthalpy change (∆H), entropy change (∆S), and Gibbs free energy (∆G), you can use the equation:

∆G = ∆H - T∆S

where T is the temperature in Kelvin.

In this case, if the enthalpy change (∆H) is positive, it means the reaction is endothermic as it absorbs heat from the surroundings. If the entropy change (∆S) is negative, it means that the disorder or randomness of the system decreases. Lastly, if the Gibbs free energy (∆G) is positive, it indicates that the reaction is not spontaneous in the forward direction.

To determine the possible result of the reaction, we need to consider the relationship between ∆G, ∆H, and ∆S. If ∆G is positive, the reaction will be nonspontaneous in the forward direction unless ∆H and ∆S can compensate for that.

The spontaneity of a reaction can be determined by looking at the sign of ∆G. If ∆G < 0, the reaction is spontaneous. If ∆G > 0, the reaction is nonspontaneous. If ∆G = 0, the reaction is at equilibrium.

Based on the given information (∆H > 0, ∆S < 0, and ∆G > 0), the correct option would be:

B. Nonspontaneous, if the temperature is low

This is because a positive ∆G suggests that the reaction is nonspontaneous. However, it is important to note that the temperature can influence the spontaneity. While the reaction is nonspontaneous at lower temperatures, it might become spontaneous at higher temperatures if the increase in entropy (∆S) can compensate for the positive enthalpy change (∆H).