Practice Work: 17.1 Factors Affecting Chemical Equilibrium
1.If you wished to maximize the products of the following reactions, which concentrations would you lower or raise?
a. H2(g) +Br2(g)  2HBr(g)
b. CO2(g) + H2(g)  CO(g) + H2O(g)
c. SO2(g) +NO2(g)  SO3(g) + NO(g)
d. C(s) + CO2(g)  2CO(g)
2.For each reaction, state whether increasing or decreasing the volume of the reaction vessel would yield more product at
equilibrium. Give the reason for your choice.
a. N2O4(g)  2NO2(g)
b. 2SO3(g)  2SO2(g) + O2(g)
c. CH4(g) + 2O2(g)  CO2(g) +2H2O(g)
d. 2CO(g) + O2(g)  2CO2(g)
3.What effect would an increase in temperature have on these reactions at equilibrium? Why?
a. Heat + H2(g) + I2(g)  2HI(g)
b. CH4(g) + 2O2(g)  CO(g) + 2H2O + heat
c. N2(g) + 3H2(g)  2NH3(g) + heat
d. Heat + CH4(g)  C(s) + 2H2(g)
4. Use Le Châtelier’s principle to predict how each of the following changes would affect this equilibrium.
C2H4O(g)  CH4(g) + CO(g)
a. adding CH4(g) to the system
b. removing CO(g) from the system
c. removing C2H4O(g) from the system
5. How would decreasing the volume of the reaction vessel affect these equilibria?
a. CO(g) + H2(g)  H2CO(g)
b. NH4HS(s)  NH3(g) + H2S(g)
c. 2NbCl4(g)  NbCl3(g) + NbCl5(g)
d. 2SO3(g) + CO2(g)  CS2(g) + 4O2(g)
6. Phosphorus pentachloride decomposes exothermically to form phosphorus trichloride and chlorine.
PCl5(g)  PCl3(g) + Cl2(g) + heat
How would you regulate the temperature of this equilibrium in order to do the following?
a. increase the concentration of PCl5
b. decrease the concentration of PCl3
c. increase the amount of Cl2 in the system
d. decrease Keq
7. Predict how this equilibrium would respond to a simultaneous decrease in both temperature and pressure.
N2O4(g)  2NO2(g) H° = +58 kJ
Review
8.Is it possible to cause a shift in an equilibrium system without changing the equilibrium constant? Explain.
9.In a reversible endothermic reaction, four moles of gaseous reactants yield three moles of gaseous products. Describe four
ways to shift this equilibrium toward the products.