Dry ice CO2 s has a melting temperature of 78o C and will no

Dry ice, CO2 (s), has a melting temperature of -78o C and will not form a liquid unless atmospheric pressure exceeds 5.1 atm. The following reaction is conducted at -90o C and 101.325 kPa: CO2 (g) ? CO2 (s)
Describe the entropy change of this reaction, ?Sreaction, under these conditions.

A. ?Sreaction does not change

B. ?Sreaction > 0
C. ?Sreaction < 0
D. ?Sreaction = 0
E. all the above
F. none of the above

Solution

C. ?Sreaction < 0

because the volume as well as randomness decreses