Exercises
Exercise 1. Consider the following reaction that is at equilibrium.
What effect would the following changes have on the position of equilibrium?
There are 3 moles of gas on the reactant side and 3 moles of gas on the product side. Increasing or decreasing the pressure will have no effect.
b) increase the concentration of Fe
no effect because Fe is a solid.
c) decrease the concentration of H2O
the reaction will shift to the left
d) increase the pressure by decreasing the volume of the reaction vessel
No effect (see a)
e) add some helium gas
no effect. Helium gas is not in the equilibrium constant expression
f) remove some H2
reaction will shift to the right
g) continuously remove H2 as soon as the reaction starts
the reaction will never reach equilibrium. The reaction will continue until one of the reactants is used up.
h) remove some Fe2O3
No effect since Fe2O3 is a solid.
Back to Le Chatelier’s Principle Study Guide
Exercise 2. Consider the following reaction:
Will the amount of CO2 decrease or increase if the temperature is decreased? Will this affect the value of the equilibrium constant, and if so, how?
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Exercise 3. Consider the following reaction at equilibrium.
How will the following changes affect the position of equilibrium? Which changes would increase the yield of NO?
The reaction would shift right. The concentration of NO would increase which means the yield of NO would increase.
b) increase volume of reaction flask
An increase in the volume will decrease the pressure. The reaction would shift to the right. The yield of NO would increase.
c) increase the pressure by decreasing the volume
If the pressure is increased, the reaction would shift to the side with fewer moles of gas. There are 9 moles of gas on the reactant side, and 10 moles of gas on the product side. The reaction would shift the left resulting in a decrease of the amount of NO.
d) increase the temperature
The reaction is exothermic. An increase in temperature would cause the reaction to shift to the left, decreasing the yield of NO.
e) decrease the temperature
The reaction is exothermic. A decrease in temperature would cause the reaction to shift to the right which would increase the yield of NO.
f) add a catalyst
A catalyst will not affect the position of equilibrium, therefore, the yield of NO will not increase or decrease.
g) remove some water vapor
The reaction would shift to the right. This would increase the yield of NO