Download Exam Review Chapter 18-Equilibrium

Exam Review Chapter 18-Equilibrium
Key concepts:
Collisions theory
Factors affecting reaction rates (Incl. affect of catalysts, activation energy)
Dynamic equilibrium
LeChatelier’s Principle
Keq
Ksp
1. What effect does increasing the concentration have on rates of reactions?
a. Increases the number of collisions
b. Increases the energy with which molecules collide
c. Both a and b
d. None of the above
2. Which of the following is not true about the effect of a catalyst
a. Permit reactions to proceed along a lower energy path
b. Are not used up in the reaction
c. Must be combined with increased temperature
d. Inhibitors interfere with the effects of a catalyst
3. When 0.1M HCl is added to the following system at equilibrium:
AgCl(s) ↔Ag+(aq)+ Cl-(aq)
the point of equilibrium will shift to the
a. right and the concentration of Ag+(aq) will decrease.
b. right and the concentration of Ag+(aq) will increase.
c. left and the concentration of Ag+(aq) will decrease.
d. left and the concentration of Ag+(aq) will increase.
4. What is the expression for Keq for this reaction?
5. In an equilibrium reaction with a Keq of 1 x108
a. reactants are favored.
c. products are favored.
b. the reaction is nonspontaneous. d. the reaction is exothermic.
6. What is the effect of adding more CO2 to the following equilibrium
reaction?
CO2 + H2O↔ H2CO3
a. More H2CO3 is produced.
b. More H2O is produced.
c. The equilibrium
d. No Change
7. Two opposing reactions (A + B ↔C + D) occurring simultaneously
at the same rate is an example of:
a. reversibility.
c. neither a nor b
b. chemical equilibrium. d. both a and b
8. According to collision theory, in order for a chemical reaction to
occur, the reactant atoms must:
a. make contact with each other.
b. have a minimum level of kinetic energy.
c. form an activated complex.
d. all of the above
9. In general, increasing temperature causes the rate of most chemical
reactions to:
a. increase. c. remain the same.
b. decrease. d. vary unpredictably.
10. Which of the following is true concerning the impact of increasing
temperature on reaction rates?
a. The number of collisions between reactant atoms is increased.
b. The energy of each reactant atom is increased.
c. The percentage of collisions with sufficient energy to cross the
activation energy barrier is increased.
d. all of the above
11. Given the following system at equilibrium:
N2(g) +3H2(g) ↔2NH3(g)
what would be the effect of removing NH3(g) as it is formed?
a. The equilibrium would shift to the left.
b. More N2(g) would be produced.
c. More H2(g) would be produced.
d. The equilibrium would shift to the right
12. Given the following system at equilibrium:
H2O(l) +heat ↔H2O(g) how would a decrease in temperature affect the
system?
a. The equilibrium would shift to the right.
b. More H2O(l) would be produced.
c. More H2O(g) would be produced.
d. The levels of reactants and products would remain the same.
13. Which of the following would increase the yield of CO(g) in the
following equilibrium system?
C(s) +H2O(g) + heat ↔CO(g) + H2(g)
a. decreasing temperature
c. adding H2(g)
b. increasing pressure
d. adding H2O(g)
14. What is the expression for Keq for the following reaction?
15. Calculate the value of Keq for this reaction at equilibrium.
2NOCl(g) ↔2NO(g) + Cl2(g)
An analysis of the equilibrium mixture in a 1-L flask gives the following
results:
NOCl, 0.30 mol; NO, 1.2 mol; Cl2, 0.60 mol.
16. Carbon monoxide and hydrogen are combined in the commercial
preparation of methyl alcohol. At a certain set of conditions, the equilibrium
mixture contains 0.020 mol/L of CO, 0.60 mol/L of H2, and the equilibrium
constant is 2.2 x102. What is the concentration of CH3OH in the equilibrium
mixture?
17. Predict the changes in the equilibrium position for this reaction when the
following changes are made:
2A(g) + B(g) ↔4C(g) + heat
a. decrease the concentration of C
b. add more heat
c. increase the concentration of A
d. increase the pressure
In each case, state whether the change causes a shift that favors the
formation of reactants or of products.
18. Which compound, PbF2 (Ksp = 3.6 x10-8) or AgBr (Ksp= 5.0 x10-13) has
the higher solubility?
19. Caculate the Sulfide ion concentration in a saturated ZnS solution if the
Ksp is 3.0 x 10-23.
20. Write the Ksp expression for a saturated solution of Ca(OH)2.
21. Calculate the concentration of Pb2+ ions in a saturated solution of
PbCrO4 if the Ksp is 1.8 x 10-14.
22. A 5.0 L vessel contained 6.0 mol of SO2, 2.5 mol of NO2 and 1.0 mol of SO3. At
equilibrium the vessel was found to contain 3.0 mol of SO3. Calculate Keq.
SO2 (g) + NO2 (g) ↔
SO2
SO3 (g) + NO (g)
NO2
SO3
NO
I
C
E
23. A 10.0 L bulb is filled with 4.0 mol of SO2, 2.2 mol of O2 and 5.6 mol of SO3. After
equilibrium of the formation reaction, there was 2.6 mol of SO2. Calculate Keq.
2SO2 (g) + O2 (g) ↔
SO2
2SO3 (g)
O2
SO3
I
C
E
24. Consider the equilibrium 3I2(g) + 6F2(g) <--> 2IF5(g) + I4F2(g)
a) At a certain temperature 3.0mol of F2 and 2.0 mol of I2 are introduced into
a 10.0L container. At equilibrium the concentration of I4F2 is 0.020 mol/L.
Calculate Keq.