Chapters 10 and 11 Practice MC

Transcription

1 Chapters 10 and 11 Practice MC Multiple Choice Identify the choice that best completes the statement or answers the question. d 1. Which of the following best describes the rates of chemical reaction? a. Most chemical reactions occur very slowly. b. Most chemical reactions occur at moderate rates. c. Most chemical reactions occur very rapidly. d. Chemical reactions have a wide range of rates, from extremely fast to extremely slow. _c 2. Which of the following is true of effective collisions? a. The number of effective collisions determines the reaction rate. b. The number of effective collisions increases as the temperature is increased. _d 3. Many molecular collisions do not result in chemical reaction. Why is this? a. The colliding molecules are not the correct chemicals. b. The colliding molecules do not have sufficient energy. c. The colliding molecules do not have the correct orientations. d. all of the above c 4. Given that the reaction 2 H 2(g) O 2(g) 2 H 2O(g) is exothermic, which of the following is true of the reaction 2 H 2O(g) 2 H 2(g) O 2(g)? a. Its activation energy is lower than that of 2 H 2(g) O 2(g ) 2 H 2O(g). b. Its activation energy is the same as that of 2 H 2(g) O 2(g ) 2 H 2O(g). c. Its activation energy is higher than that of 2 H 2(g) O 2(g ) 2 H 2O(g). d. There is no relationship between its activation energy and that of 2 H 2(g) O 2(g ) 2 H 2O(g). c 5. In an energy diagram for an exothermic chemical reaction which of the following is true? a. The energy of the products is lower than that of the reactants. b. The activation energy is higher than that of the reactants b 6. In an energy diagram for an endothermic chemical reaction which of the following is true? a. The energy of the products is lower than that of the reactants. b. The activation energy is higher than the energy of the reactants. _c 7. Which of the following is the best definition of a catalyst? a. A catalyst is a material which speeds up the rate of a chemical reaction. b. A catalyst is a material which speeds up the rate of a chemical reaction without participating in the reaction. c. A catalyst is a material which speeds up the rate of a chemical reaction without being consumed during the reaction. d. All of the above are equally good definitions. a 8. A catalyst speeds up a chemical reaction as a result of which of the following? a. It provides an alternate pathway with a lower activation energy. b. It increases the number of collisions between reacting molecules. c. It makes the reaction more endothermic. d. It makes the reaction more exothermic.

2 c 9. Which of the following is true of a reaction which has reached equilibrium? a. The reactants have been completely converted to products. b. The rate of the forward reaction is faster than the rate of the reverse reaction. c. The rate of the forward reaction is equal to the rate of the reverse reaction. d. The rate of the forward reaction is slower than the rate of the reverse reaction. c 10. In writing the equilibrium constant expression we use square brackets. The notation [A] means which of the following? a. the mass of A c. the molar concentration of A b. the number of moles of A d. none of the above a 11. Which of the following must we know in order to write the equilibrium constant expression for a chemical reaction? a. the balanced chemical equation for the reaction b. the rate at which the reaction occurs c 12. For the reaction which of the following is the equilibrium constant expression? a. K eq = [H 2][N 2]/[NH 3] c. K eq = [H 2] 3 [N 2]/[NH 3] 2 b. K eq = [NH 3]/[H 2][N 2] d. K eq = [NH 3] 2 /[H 2] 3 [N 2] a 13. For the reaction at 25 C equilibrium is established when [NOCl] = 2.6 M, [NO] = 1.4 M and [Cl 2] = 0.34 M. What is the value of the equilibrium constant for this reaction? a c. 5.4 b d d 14. Which of the following could be the equilibrium constant for a reaction which proceeds very far in the direction of the products? a c b d c 15. Which of the following is generally not included when writing an equilibrium constant expression? a. liquids b. solids c 16. Which of the following will change the numerical value of the equilibrium constant of a particular reaction? a. increasing the concentration of reactants b. increasing the concentration of products c. increasing the temperature d. all of the above b 17. A particular reaction has an equilibrium constant of Which of the following best describes the relationship between the equilibrium constant and the reaction rate? a. Because the equilibrium constant is large the reaction proceeds rapidly. b. There is no relationship between the size of the equilibrium constant and the rate of the reaction. c. Both a and b are true. d. Neither a nor b is true.

3 c 18. Le Châtelier s Principle applies to which of the following systems? a. a system in which the reaction is moving left to right b. a system in which the reaction is moving right to left c. a system which has reached equilibrium d. all of the above b 19. What is the effect of adding H 2O(g) to a container in which the reaction has reached equilibrium? a. The reaction will shift left to right. b. The reaction will shift right to left. c. There will be no effect. d. What happens depends on the temperature. b 20. If the exothermic reaction H 2(g) I 2(g) 2HI(g) has reached equilibrium, what is the effect of raising the temperature of the reaction vessel? a. The reaction will shift left to right. b. The reaction will shift right to left. c. There will be no effect. d. What happens depends on the initial temperature. b 21. If the endothermic reaction has reached equilibrium, what is the effect of lowering the temperature of the reaction vessel? a. The reaction will shift left to right. b. The reaction will shift right to left. c. There will be no further reaction. d. What happens depends on the temperature. d 22. When considering the effect of a catalyst on a system to which Le Chatelier s Principle can be applied, which of the following is true? a. Addition of a catalyst has absolutely no effect on the reaction. b. Addition of a catalyst speeds up the forward reaction. c. Addition of a catalyst speeds up the reverse reaction. d. Addition of a catalyst speeds up both the forward and reverse reaction by the same amount. Consider the following energy diagram for a reaction for questions 23-26

4 _b 23. Which of the following correctly represents this reaction? a. The energy of the products is less than that of the reactants so the reaction is endothermic. b. The energy of the products is greater than that of the reactants so the reaction is endothermic. c. The energy of the products is less than that of the reactants so the reaction is exothermic. d. The energy of the products is greater than that of the reactants so the reaction is exothermic. b 24. Which letter represents the activation energy for the reaction? a. A b. B c. C d. D e. E _d 25. Which letter represents the net energy change of the reaction? a. A b. B c. C d. D e. E b 26. If a catalyst was added to the reaction represented, which of the following would change position? a. A b. B c. C d. D e. E f. A and E g. B and C c 27. The species H 3O known as a. heavy water c. The hydronium ion b. The hydrogen ion d. all of these c 28. The species H can be called which of the following? a. hydrogen ion c. either a or b b. proton c 29. Which of the following occurs when NaOH is dissolved in water to form a basic solution? a. A complex between NaOH and water is formed. b. NaOH breaks up to form Na (aq), H (aq) and O 2 (aq). c. NaOH breaks up to form Na (aq) and OH (aq). d. The water molecule loses an H. Use the following equation for ammonia dissolved in water to answer questions NH 3(aq) H 2O (l) NH 4 (aq) OH - (aq) b 30. Which of the following occurs when ammonia, NH 3, is dissolved in water? a. A very small number of ammonia molecules break up. b. A very small number of ammonia molecules take an H from the water. c. A very small number of molecules of NH 4OH are formed. d. A very small number of water molecules take an H from ammonia.

5 d 31. Which of the following terms best describes aqueous ammonia? a. It is a strong acid b. it is a strong base c. it is a weak acid d. it is a weak base c 32. Why does the label ammonium hydroxide, NH 4OH (aq), on a bottle give a false impression about the bottle s contents? a. There is a large amount of NH 4 (aq) but only a small amount of OH (aq). b. There is a small amount of NH 4 (aq) but only a large amount of OH (aq). c. There is a large amount of NH 3(aq) but only small amount of NH 4 (aq) and OH (aq). d. None of the above, the label accurately describes the contents. c 33. Which of the following is the Brønsted-Lowry definition of an acid? a. a hydroxide ion acceptor c. a proton donor b. a proton acceptor d. none of these b 34. Which of the following is the Brønsted-Lowry definition of a base? a. a hydroxide ion acceptor c. a proton donor b. a proton acceptor d. none of these c 35. Which of the following is the conjugate base of water? a. H 3O c. OH b. NaOH d. O 2 _b 36. Which of the following is the conjugate acid of water? a. HCl c. NH 4 b. H 3O d. OH d 37. Which of the following is not an acid? a. H 3O 2 c. HPO 4 b. H 2CO 3 d. None, they are all acids. b 38. What is the name of the acid which dissociates to give the nitrate ion, NO 3? a. hydronitric acid c. nitritic acid b. nitric acid d. nitrous acid d 39. Sulfites, salts of the anion, SO 3 2 are found in wines as preservatives. The acid associated with the sulfite ion is H 2SO 3. What is the name of H 2SO 3? a. hydrosulfuric acid c. sulfuric acid b. hydrosulfuous acid d. sulfurous acid d 40. What are the two acids in the following reaction? a. NH 4 and HPO 42 b. NH 4 and NH 3 c. HPO 42 and H 2PO 4 d. NH 4 and H 2PO 4 NH 4 (aq) HPO 4 2 NH 3 H 2PO 4 _d 41. Which of the following is the correct expression for K w of water? a. [H 3O ][OH ]/[H 2O] c. [H 3O ][OH ]/[H 2O] 2 b. [H 2O]/[ H 3O ][OH ] d. [H 3O ][OH ] d 42. Which of the following is the numerical value of K w for water at room temperature? a c b d

6 b 43. Which of the following is true of pure water? a. [H 3O ] < [OH ] c. [H 3O ] > [OH ] b. [H 3O ] = [OH ] d. pure water is an electrolyte b 44. In an aqueous solution the [H 3O ] is 1.0 x 10-6 M. What is the [OH-]? a M c M b M d M c 45. Which of the following is the definition of ph? a ph c. log[h 3O ] b. log[h 3O ] d. none of these c 46. Which of the following is the correct relationship between ph and poh? a. (ph) (poh) = 14 c. ph poh = 14 b. ph/poh = 14 d. ph poh = 14 a 47. Which of the following ph s corresponds to a highly acidic solution? a. 2.8 c. 7.2 b. 6.8 d c 48. Which of the following ph s corresponds to a slightly basic solution? a. 2.8 c. 7.2 b. 6.8 d d 49. A solution has a ph of 5.4. What is its poh? a. 8.6 c. 5.4 b. 5.4 d. 8.6 c 50. An ammonia solution has a ph of 8.30, what is the [H 3O ] in this solution? a M c M b M d M _b 51. An ammonia solution has a ph of 8.30, what is the [OH ] in this solution? a M c M b M d M