Equilibrium Problem Set 4
Le Châtelier’s Principle
Name ______________________________
Period _____
Date ____________
10 points – do all problems
1. Suppose the reaction system: UO2 (s) + 4 HF (g)  UF4 (g) + 2 H2O (g) has already reached equilibrium.
Predict the effect that each of the following changes will have on the equilibrium position. Tell whether the
reaction will shift to the right, shift to the left, or remain unaffected.
a. Additional UO2 (s) is added to the system.
2 points
b. The reaction is performed in a glass reaction vessel; HF
(g)
attacks and reacts with glass.
c. Water vapor is removed.
2.
4 NH3 (g) + 5 O2 (g)  4 NO (g) + 6 H2O (g)
∆H° = -904.4 kJ
How does each of the following affect the yield of NO at equilibrium (increase, decrease, no effect)?
a. Increase in [NH3]
b. Increase in [H2O]
2 points
c.
Decrease in [O2]
d.
Decrease in the volume of the container in which the reaction occurs
e. Addition of a catalyst
f.
Increase in temperature
3. What will happen to the number of moles of SO3 in equilibrium with SO2 and O2 in each of the following cases?
2 SO3 (g)  2 SO2 (g) + O2 (g)
a. Oxygen gas is added.
2 points
b.
The pressure is increased by decreasing the volume of the reaction container.
c.
In a rigid reaction container, the pressure is increased by adding argon gas.
d. The temperature is decreased (the reaction is endothermic).
e. Gaseous sulfur dioxide is removed.
4. Old-fashioned “smelling salts” consist of ammonium carbonate, (NH 4)2CO3. The reaction for the decomposition of
ammonium carbonate, (NH4)2CO3 (s)  2 NH3 (g) + CO2 (g) + H2O (g) is endothermic. Would the smell of
ammonia increase or decrease as the temperature is increased?
1 point
5. Methanol (CH3OH) can be made by the reaction of CO with H2: CO (g) + 2 H2 (g)  CH3OH (g)
a. Use the following thermochemical data to calculate ∆H° for this reaction:
CO (g)
-110.5 kJ/mol
CH3OH (g)
-201.0 kJ/mol
3 points
b.
To maximize the equilibrium yield of methanol, would you use a high or low temperature?
c. To maximize the equilibrium yield of methanol, would you use a high or low pressure?