- Principles of Chemistry II: Honors
Spring 2016, Unique 494200
Homework, Week 3
1. Most of the portable red fire extinguishers that you see in public buildings or can purchase for your home (the so-called “ABC dry chemical” extinguishers) contain powdered sodium bicarbonate that decomposes when exposed to high temperature (for example from a fire) into sodium carbonate, water, and carbon dioxide:
2 NaHCO3(s) --> Na2CO3(s) + H2O(g) + CO2(g)
a) Determine the equilibrium constant of the reaction at 150˚C.
b) At equilibrium, if the partial pressure of CO2(g) is 0.80 atm, what is the partial pressure of H2O(g)?2. How do the equilibrium constants for the following two reactions compare at 25˚C:
Reaction 1: CS2(g) + 3 O2(g) --> CO2(g) + 2 SO2(g)
Reaction 2: 1/3 CS2(g) + O2(g) --> 1/3 CO2(g) + 2/3 SO2(g)
3. Determine the equilibrium constant for reaction 3 (K3) in terms of the equilibrium constants for reactions 1 and 2 (K1 and K2):
Reaction 1: XeF6(g) + H2O(g) --> XeOF4(g) + 2 HF(g)
Reaction 2: XeO4(g) + XeF6(g) --> XeOF4(g) + XeO3F2(g)
Reaction 3: XeO4(g) + 2 HF(g) --> XeO3F2(g) + H2O(g)
4. Phosphorous pentachloride (PCl5) decomposes into phosphorous trichloride (PCl3) and chlorine gas. 1.5 g of PCl5 is placed into a 10 mL sealed vessel and heated to 250˚C, (which is above its sublimation temperature). Determine the partial pressure of all species at equilibrium.