Question

The following drawing is a representation of a reaction of the type A → B, where different shaded spheres represent different molecular structures. For this reaction ΔH° = -30 kJ. This reaction is likely to be Select one: A. nonspontaneous at all temperatures. B. nonspontaneous at low temperatures and spontaneous at high temperatures. C. spontaneous at low temperatures and nonspontaneous at high temperatures. D. spontaneous at all temperatures.

Answer 1

Answer: The given reaction is non-spontaneous at low temperatures and spontaneous at high temperatures.

Explanation:

We know that relation between free energy and enthalpy is as follows.

             $\Delta G = \Delta H - T\Delta S$

As in the given drawing, solid is converting into gas. This means that there is occurring an increase in entropy of the system. This also means that the enthalpy change will also be positive.

Free energy change is negative (spontaneous) at high temperature and free energy change is positive at low temperature.

Hence, we can conclude that the given reaction is non-spontaneous at low temperatures and spontaneous at high temperatures.