CHM 2046C Sample Module 13 Name: ___Answers_____

Part B Entropy: Disorder and Spontaneity 10 points

1. What six types of processes or reactions lead to an increase in entropy?

2. How are entropy, enthalpy, and the spontaneity of a reaction related?

The reaction is spontaneous if ___________________________.

The possibilities are:

∆H^osys	∆S^osys	Result
(exothermic)
(exothermic)
(endothermic)
(endothermic)

3. Which of the following processes are spontaneous and which are nonspontaneous:

(a) diffusion of perfume molecules from one side of the room to the other.

(b) Heat flow from a cold piece of metal (2^oC)to hot water(70^oC) when the cold metal is dropped into the hot water.

(c) Decomposition of rust (Fe₂O₃∙H₂O) to iron metal, oxygen gas, and water.

(d) Decomposition of solid CaCO₃ to solid CaO and gaseous CO₂ at 25^oC and 1 atm pressure (K_p = 1.4 x 10 ^-23)

4. Predict the sign of ∆S in the system for each of the following processes:

(a) CO₂ (s) ---> CO₂ (g) (sublimation of dry ice)

(b) CaSO₄(s) ---> CaO(s) + SO₂(g)

(c) N₂(g) + 3 H₂ (g) ---> 2 NH₃ (g)

(d) I₂(s) ---> I₂ (aq) (dissolution of iodine in water)