Question

You observe that carbon dioxide sublimes. Which of the following statements about the signs of this process is/are true?

(I) Work (w) is positive.

(II) Heat (q) is negative.

(III) Change in Gibbs free energy (∆G) is positive.

(IV) Change in entropy (∆S) is positive.

1. II and III

2. I only

3. I and II

4. I, II and III

5. IV only

6. III and IV

Answer 1

Correct option 5. IV only

Explanation:

Sublimation results in a significant increase in the volume of the system, allowing it to do work on its surroundings, i.e. the pressure-volume work function is negative. Sublimation is also an endothermic process, making heat positive. Since the process described ”happens” as a given in the problem, the change in free energy must be negative. Change in entropy must be positive since a solid is becoming a gas.