III. Gas-Phase Equilibria
III-1. Introduction and Background III-2. Sample Problem III-3. List of Problems III-4. Simple Problems III-5. Advanced Problems

Print this list and try working these problems before checking your answers and looking at the hints.

Simple Problems

• III-4(1). What are the equilibrium partial pressures of N2O4 and NO2 when 1.000 atm of N2O4 is introduced into a 500.0 mL container at room temperature?
Unbalanced reaction: N2O4 (g) NO2 (g)     Keq = 0.144 at 25oC.
• III-4(2). What is the equilibrium constant, Keq, for the reaction below if the following partial pressures were measured at equilibrium: PSO2 = 0.55 atm, PO2 = 0.30 atm, and PSO3 = 0.15 atm.
Unbalanced reaction: SO2 (g) + O2 (g) SO3 (g).
• III-4(3). What are the equilibrium partial pressures of all gases when 1.00 atm of H2O(g) is heated with coke to 900 K?
Unbalanced reaction: C(s) + H2O(g) CO(g) + H2 (g)     Keq = 0.45 at 900 K.

• III-5(1). What are the equilibrium partial pressures of N2O4 and NO2 when 0.20 mol of N2O4 and 0.80 mol of NO2 are sealed in a 2.00 L container and placed on a steam bath?     Keq = 11 at 100oC.
Unbalanced reaction: N2O4 (g) NO2 (g)     Keq = 11 at 100oC.
• III-5(2). What is the equilibrium partial pressure of carbon dioxide when 50.0 g of calcium carbonate is heated to 900oC in a 100.0 mL flask that was sealed and evacuated before heating.
Unbalanced reaction: CaCO3 (s) CaO(s) + CO2 (g)     Keq = 1.04 atm at 900oC.
• III-5(3). In problem III-3(3), you found the equilibrium partial pressures when 1.00 atm of H2O(g) is heated with coke to 900 K. The equilibrium partial pressures were:
PH2O = 0.52 atm       PCO = 0.48 atm       PH2 = 0.48 atm
What are the new equilibrium partial pressures of all gases if the volume containing this equilibrium mixture is increased by a factor of 4?

Unbalanced reaction: C(s) + H2O(g) CO(g) + H2 (g)     Keq = 0.45 at 900 K.

CHP Home Equilibrium Practice Problems