Chapter Practice Test

Transcription

1 Name: Class: Date: Chapter Practice Test Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Examining a chemical system before and after a reaction reveals the a. net chemical change. c. intermediates. b. reaction mechanism. d. activated complex. 2. In the reaction represented by the following equation, a possible intermediate is H 2 (g) + I 2 (g) 2HI(g) a. H 2. c. H 2 I. b. HI. d. I Reactions whose reactants and products exist in a single phase are called a. reaction mechanisms. c. homogeneous reactions. b. heterogeneous reactions. d. activated complexes. 4. What is the overall equation for the formation of hydrogen iodide from its elements? a. H(g) + I(g) HI(g) b. H 2 (g) + I 2 (g) 2HI(g) c. H(g) + I 2 (g) HI(g) + I(g) d. H 2 (g) + I(g) HI(g) + H(g) 5. To react, gas particles must a. be in the same physical state. c. have different energies. b. have the same energy. d. collide. 6. If colliding molecules have an orientation that favors reaction, they have a. the correct angles and distances between atoms. b. sufficient energy for each molecule. c. speeds that are neither too fast nor too slow. d. entropy values in the proper range. 7. Which attempts to explain chemical reactions and physical interactions of molecules? a. chemical kinetics c. thermodynamics b. collision theory d. thermochemistry 8. If a collision between molecules is very gentle, the molecules are a. more likely to be favorably oriented. b. less likely to be favorably oriented. c. more likely to react. d. more likely to rebound without reacting. 9. A short-lived structure formed during a collision is a(n) a. reagent. c. activated complex. b. catalyst. d. inhibitor. 1

2 Name: 10. How does the energy of the activated complex compare with the energies of reactants and products? a. It is lower than the energy of both reactants and products. b. It is lower than the energy of reactants but higher than the energy of products. c. It is higher than the energy of reactants but lower than the energy of products. d. It is higher than the energy of both reactants and products. 11. Activation energy is a. the energy required to form the activated complex. b. the net energy required to turn reactants into products. c. the enthalpy of reaction. d. free energy. 12. In an energy-profile graph, the activated complex is represented at the a. left end of the curve. c. bottom of the curve. b. right end of the curve. d. top of the curve. 13. In a diagram of an activated complex, broken lines represent a. actual bonds. c. electrons. b. partial bonds. d. bond energies. 14. Raising the temperature of reactants in a system a. increases the average kinetic energy of the molecules. b. decreases the average kinetic energy of the molecules. c. decreases the rate of collision of molecules. d. has no effect on the average kinetic energy of molecules. 15. Raising the temperature of reactants in a system a. increases the average molecular motion. b. decreases the average molecular motion. c. has no effect on the average molecular motion. d. disturbs the system so that the collision theory no longer applies. 16. If a collision between molecules is oriented properly, the molecules are a. more likely to react. c. less likely to form an intermediate. b. more likely to rebound without interacting. d. less likely to react. 17. The energy change, ΔE, for a reaction is the energy difference between the a. product and the intermediate. c. product and the activated complex. b. product and the reactant. d. reactant and the intermediate. 18. The activation energy for a reaction is the energy difference between the a. product and the intermediate. c. reactant and the activated complex. b. product and the reactant. d. reactant and the intermediate. 19. Which of the following is true in an endothermic reaction? a. energy of products < activation energy < energy of reactants b. energy of reactants < activation energy < energy of products c. energy of products < energy of reactants < activation energy d. energy of reactants < energy of products < activation energy 2

3 Name: 20. Which of the following is true in an exothermic reaction? a. energy of products < activation energy < energy of reactants b. energy of reactants < activation energy < energy of products c. energy of products < energy of reactants < activation energy d. energy of reactants < energy of products < activation energy 21. Which branch of chemistry studies reaction rates? a. thermochemistry c. chemical kinetics b. thermodynamics d. calorimetry 22. Which branch of chemistry studies reaction mechanisms? a. thermochemistry c. chemical kinetics b. thermodynamics d. calorimetry 23. The usual condition for reaction, a favorable orientation, is not necessary for a. synthesis reactions. c. single-displacement reactions. b. decomposition reactions. d. double-displacement reactions. 24. Chemical kinetics studies a. the factors that affect the rate of reaction. b. the mathematical expressions for the rate of reaction. c. the factors that affect the rate of reaction and the mathematical expressions for the rate of reaction. d. the effect of quantum kinetics on chemical reactions. 25. How fast something changes with time is a(n) a. area. c. order. b. rate. d. collision. 26. Reaction rate depends upon a. both collision frequency and efficiency. b. average kinetic energy. c. collision efficiency. d. average potential energy. 27. The decrease in reactant concentration per unit time in a reaction is a measure of the a. reaction rate. c. overall reaction. b. heterogeneous reaction. d. reaction mechanism. 28. Which substance naturally combines most rapidly with oxygen? a. platinum c. iron b. sodium d. coal 29. If the surface area of reactants is larger, a. the reaction rate is generally higher. c. the reaction rate is not affected. b. the reaction rate is generally lower. d. the rate-determining step is eliminated. 30. In heterogeneous reactions, the reactants a. have unequal masses. c. have unequal volumes. b. are not equally reactive. d. are in different phases. 3

4 Name: 31. Changing the pressure of a gas is another way of changing its a. temperature. c. surface area. b. concentration. d. composition. 32. Which process is used to speed up chemical reactions? a. calorimetry c. activation b. catalysis d. inhibition 33. Which term describes a catalyst in the same phase as the reactants and products? a. homogenous c. activated b. heterogeneous d. inhibited 34. Adsorption of reactants on the surface of a metal catalyst changes the reaction rate by affecting the a. concentration of the reactants. c. properties of the reactants. b. temperature of the system. d. surface area of the reactants. 35. A substance that slows down chemical processes is called a(n) a. inhibitor. c. catalyst. b. reactant. d. indicator. 36. Catalysts generally affect chemical reactions by a. increasing the temperature of the system. b. increasing the surface area of the reactants. c. providing an alternate pathway with a lower activation energy. d. providing an alternate pathway with a higher activation energy. 37. How is a heterogeneous catalyst different from the reactants in a chemical reaction? a. The mass of the catalyst is different. b. The chemical properties of the catalyst are different. c. The energy of the catalyst is different. d. The phase of the catalyst is different. 38. In a net equation, catalysts a. are shown with the reactants. b. are shown with the products. c. are shown with both reactants and products. d. are not shown. 39. For a cost-sensitive reaction, catalysts can be a. thrown away. c. regenerated and reused. b. used as reaction inhibitors. d. used as reaction indicators. 40. A rate law relates a. reaction rate and temperature. b. reaction rate and concentrations of reactants. c. temperature and concentrations of reactants. d. energy and concentrations of reactants. 41. The letter R in a rate law stands for a. a proportionality constant. c. temperature. b. concentration. d. reaction rate. 4

5 Name: 42. The value of k in a rate law a. is the same under all conditions. c. varies with time. b. varies with concentration. d. varies with temperature. 43. How are the units for a rate always expressed? a. change in concentration unit time elapsed b. Ê ËÁ change in concentration ˆ Ê ËÁ unit time elapsed ˆ c. unit time elapsed change in concentration d. unit time elapsed 44. In the rate law for the following equation, R=k[A] n [B] m, the units for [A] and [B] are a. g -1 s -1. c. M. b. M -1 s -1. d. Ms A reaction is zero order in reactant A and second order in reactant B. What happens to the reaction rate when the concentrations of both reactants are doubled? a. The reaction rate remains the same. b. The reaction rate increases by a factor of two. c. The reaction rate increases by a factor of four. d. The reaction rate increases by a factor of eight. 46. If doubling the concentration of a reactant quadruples the rate of the reaction, the concentration of the reactant appears in the rate law with a(n) a. exponent of 1. c. exponent of 4. b. exponent of 2. d. coefficient of If a chemical reaction proceeds in a sequence of steps, the slowest step is called a. the kinetic step. c. the problem step. b. the constant step. d. the rate-determining step. 48. At equilibrium, a. all reactions have ceased. b. only the forward reaction continues. c. only the reverse reaction continues. d. both the forward and reverse reactions continue. 49. At equilibrium, a. the forward reaction rate is lower than the reverse reaction rate. b. the forward reaction rate is higher than the reverse reaction rate. c. the forward reaction rate is equal to the reverse reaction rate. d. no reactions take place. 50. What two processes are at equilibrium in a saturated sugar solution? a. evaporation and condensation c. decomposition and synthesis b. dissolving and crystallization d. ionization and recombination 5

6 Name: 51. What symbol represents the equilibrium constant? a. k c. c b. K d. R 52. A very high value of K indicates that a. equilibrium is reached slowly. c. reactants are favored. b. products are favored. d. equilibrium has been reached. 53. A value of K near 1 indicates that at equilibrium probably a. only products are present. b. only reactants are present. c. significant quantities of both products and reactants are present. d. the reactions occur at a moderate rate. 54. The equilibrium constant depends on changes in a. pressure. b. concentrations. c. temperature. d. pressure, concentrations, and temperature. 55. What is the chemical equilibrium expression for the equation 2A 2 B + 3CD A 4 D + C 3 B 2? a. È 6 A 2 B È A 2 B [ CD] È È A 4 D C3 B c. È È 2 A 4 D 2 b. È È A 4 D È È 2 A 4 D 2 È 6 A 2 B d. È A 2 B [ CD] 56. If the pressure on the equilibrium system N 2 (g) + O 2 (g) a. the quantity of N 2 (g) decreases. b. the quantity of NO(g) increases. c. the quantity of NO(g) decreases. d. the quantities in the system do not change. 2NO(g) decreases, 57. If the temperature of the equilibrium system CH 3 OH(g) kj a. [CH 3 OH] increases and [CO] decreases. b. [CH 3 OH] decreases and [CO] increases. c. [CH 3 OH] increases and [CO] increases. d. the concentrations in the system do not change. CO(g) + 2H 2 (g) increases, 58. If more CO(g) is added to the system 2CO(g) + O 2 (g) 2CO 2 (g) at constant temperature, K a. increases. c. increases or decreases. b. decreases. d. does not change. 6

7 Name: 59. If the temperature of the equilibrium system X + Y XY + 25 kj decreases, a. [X] decreases and [XY] increases. b. [X] increases and [XY] decreases. c. [X] decreases and [XY] decreases. d. the concentrations of reactants and products do not change. 60. Reactions tend to run to completion if a. a gaseous product forms and escapes. b. a product in the same phase as the reactants forms. c. one product is highly ionized. d. one product is highly soluble. 61. Reactions tend to run to completion if a product a. has a high melting point. c. is precipitated as a solid. b. is a liquid. d. is ionic. 62. The common-ion effect promotes a. dissolving. c. boiling. b. precipitation. d. ionization. 63. In which solution does adding hydrogen chloride promote precipitation? a. H 2 SO 4 c. AgNO 3 b. KBr d. NaH 64. The common-ion effect is a consequence of a. Boyle's law. c. Avogadro's principle. b. Le Châtelier's principle. d. chemical kinetics. 65. What is the symbol for the solubility-product constant? a. K c. K a b. K h d. K sp 66. If the ion product for two ions whose solutions have just been mixed is greater than the value of K sp, a. the solution is unsaturated. c. equilibrium cannot be achieved. b. precipitation occurs. d. a decomposition reaction occurs. 67. What is the solubility-product constant of barium carbonate, BaCO 3? Its solubility is g/100 g H 2 O. The molar mass of BaCO 3 is g/mol. Note: 1 g H 2 O = 1 ml a c b d What is the solubility-product constant of magnesium hydroxide, Mg(OH) 2? Its solubility is g/100 g H 2 O. The molar mass of Mg(OH) 2 is g/mol. Note: 1 g H 2 O = 1 ml a c b d What is the solubility in mol/l of silver iodide, AgI? Its K sp value is a c b d

8 Name: 70. What is the solubility in mol/l of cobalt(ii) sulfide, CoS? Its K sp value is a c b d What is the solubility in mol/l of copper(i) chloride, CuCl? Its K sp value is a c b d What is the solubility in mol/l of copper(ii) sulfide, CuS? Its K sp value is a c b d What is the solubility in mol/l of copper(i) sulfide, Cu 2 S? Its K sp value is a c b d Calculate the ion product for mixing 50. ml of M CuNO 3 with 100. ml of M NaCl. K sp for CuCl is Does a precipitate form? a ; yes c ; yes b ; no d ; no 75. Calculate the ion product for mixing 250 ml of M Cd(NO 3 ) 2 with 150 ml of M K 2 S. K sp for CdS is Does a precipitate form? a ; no c ; no b ; yes d ; yes 76. Calculate the ion product for mixing 300 ml of M Sr(NO 3 ) 2 with 200 ml of M K 2 SO 4. K sp for SrSO 4 is Does a precipitate form? a ; yes c ; yes b ; no d ; no 77. Given the following values, calculate E a for the reaction. ΔEforward = -10 kj/mol Ea = 40 kj/mol a. -30 kj/mol c. 30 kj/mol b. 10 kj/mol d. 20 kj/mol 78. The following data relate to the reaction A + B --> C. Find the rate law equation. [A] (M) [B] (M) Rate (M/s) a. R = k[a] 2 [B] 2 c. R = k[a] 2 [B] b. R = k[a][b] d. R = k[a] 3 [B] 2 8

9 Name: 79. Given the following rate law, how is the rate affected when the concentration of A is doubled, but the concentration of B is cut in half? R = k[a][b] 2 a. Rate is doubled c. Rate is halved b. Rate stays the same d. Not enough information 80. At 450 degrees C, the value of the equilibrium constant for the following system is 6.59 x If [NH 3 ] = 1.23 x 10-4 M and [H 2 ] = 2.75 x 10-2 M at equilibrium, determine the concentration of N 2 at that point. N 2(g) + 3H 2(g) ---><--- 2NH 3(g) a M c x 10-3 M b x 10-2 M d M 9