Question

For which process is ΔS negative? Group of answer choices A. grinding a large crystal of KCl to powder B. raising the temperature of 100 g Cu from 275 K to 295 K C. compressing 1 mol Ne at constant temperature from 1.5 L to 0.5 D. mixing 5 mL ethanol with 25 mL water E. evaporation of 1 mol of CCl4(l)

Answer 1

Answer:

C.

Explanation:

The entropy (S) is the measure of the randomness of a system, and ΔS = Sfinal - Sinitial. As higher is the disorder of the system, as higher is the entropy.

A. When KCl is fractionated in power, there'll be more portions of it, so, the disorder must be higher, then ΔS is positive.

B. As higher is the temperature, higher is the kinetic energy of the system, and because of that, the disorder is also higher, so ΔS is positive.

C. The decrease in the volume (compression) decreases the distance between the molecules, so the system will be more organized, then ΔS is negative.

D. The volume before the mixing will be higher, and the ethanol will dissociate, so it will be more particles, the disorder will increase, and ΔS is positive.

E. Sgas > Sliquid > Ssolid because of the disorder of the molecules, then ΔS is positive.