CHEM 1215 -- Unit 4 Practice Problems -- Part 1 Equilibrium

 

 

 

1.      Write the equilibrium constant expressions (Kc) for the following reactions.

a.      2 SO2 (g) + O2 (g)        2 SO3 (g)

 

b.      FeO (s) + H2 (g)         Fe (s) + H2O (g)

 

 

2.      Write the equilibrium constant expression (Kp) for reaction (a) in question 1.

 

 

 

3.      At equilibrium, the reaction N2(g) + 3H2(g)          2NH3(g) had the following concentrations:  [N2] = 0.0850 M, [H2] = 3.10 x 10-3 M, and [NH3] = 0.0310 M.  What is the value of Kc ?

 

 

4.      Write the solubility product constant expression for the dissolution of chromium (III) hydroxide.

 

 

5.      Calculate the concentration of silver ions and phosphate ions present in a saturated solution of silver phosphate if Ksp = 2.6 x 10-18 .

 

 

6.      Sulfur trioxide decomposes at high temperature in a sealed container:

 

2 SO3 (g)                   2 SO2 (g) + O2 (g)

 

      Initially, the vessel is charged at 1000K with SO3 (g) at a concentration of 6.09 x 10-3 M.  At equilibrium, the SO3 concentration is 2.44 x 10-3 M. 

 

a.   What are the equilibrium concentrations of SO2 and O2?

 

 

b.   What is the value of Kc at 1000 K?

 

 

 

7.      The Kp at 450oC for the equilibrium:  N2(g) + 3 H2 (g)          2 NH3 (g) is 4.51 x 10-5. 

 

a.      If 105 atm NH3 (g), 35 atm N2 (g), and 495 atm H2 (g) are present in a reactor, calculate the reaction quotient, Q.

 

b.      Is the system at equilibrium?  If not, which direction must the mixture shift in order to achieve equilibrium?

c.      When the system reaches equilibrium, will the partial pressure of ammonia be higher or lower than the partial pressure of ammonia shown in part a?

d.      What is the value of Kp for the reaction 2 NH3 (g)          N2 (g) + 3 H2 (g)?

 

 

8.      A 2.000 L reactor is filled with 1.000 mol H2 (g) and 2.000 mol I2 (g) at 448oC.  The value of the rate constant, Kc, for the reaction H2 (g) + I2 (g)           2 HI (g) at 448oC is 50.5.  What are the concentrations of H2, I2, and HI at equilibrium?

 

9.      Kc for the decomposition of iodine monobromide gas to form iodine and bromine vapors is 8.5 x 10-3.  Calculate the concentration of all reactants and products when a mixture 0.100 M in each of the reactants and products is allowed to reach equilibrium

 

10.  Given the reaction NO (g) + O3 (g)          NO2 (g) + O2 (g)  DH = -199 kJ, what happens when:

a.      NO is added?

b.      NO2 is added?

c.      The volume of the container is doubled?

d.      The reaction is heated?

e.      O3 is removed?

f.        NO2 is removed?

g.      Ar (g) is added to increase the total pressure?

h.      Powdered nickel is added as a catalyst?

 

 

11.  Given a saturated solution of aluminum hydroxide, what happens to the [Al3+] when each of the following changes is made?  (Hint: Write a balanced equation first for this equilibrium system.)

a.   0.25 g of solid aluminum hydroxide is added

b.   0.25 g of solid sodium hydroxide is added

c.   6 mL of 12 M HCl is added

 

12.  A student measured the equilibrium constant for the formation of [Fe(SCN)]2+ from Fe3+ and SCN-.  In one experiment a solution prepared by mixing 5.00 mL of 0.00800 M Fe(NO3)3, 10.0 mL of 0.00400 M KSCN, and 5.00 mL of 0.500 M HNO3 contained 4.83 x 10-4 M [Fe(SCN)]2+ at equilibrium.  Calculate the equilibrium constant for the reaction.