Question

1. Cl2(g) -> 2Cl(g)
2. H2(g) at 5.0 atm -> H2(g) at 1.0 atm
3. sublimation of solid CO2
4. 2H2(g) + O2(g) -> 2H20(g)
5. PCl5(g) <-> PCl3(g) + Cl2(g)

A. The change in entropy will be positive.
B. The change in entropy will be zero.
C. The change in entropy will be negative.
D. The change in entropy can either be positive or negative.
E. The change in entropy cannot be determined from the information given.

[I'm horribly lost in this chapter...]

i've looked in my book for entropy and i figured out that 3 was A, and 5 was E. I'm still stuck on the others.

Think in terms of order. Solid CO2, for example, has some kind of a crystalline arrangement while the gas does not, so the entropy change should be negative since it will be going from a more ordered arrangement to a less ordered arrangement.

Answer 1

1. A
2. A
3. A
4. C
5. B