Chemistry 12 Provincial Workbook Unit 02: Chemical Equilibrium
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R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 1 / 63 Chemistry 12 Provincial Workbook Unit 02: Chemical Equilibrium Multiple Choice Questions 1. Consider the following... Which of the following lists these equilibria from the one that most favours products to the one that least favours products? A. I, II, III B. I, III, II C. II, III, I D. III, I, II 2. Consider the following equilibrium system... Ni(s)+4CO(g) Ni CO4 (g), ΔH= - 603kJ Which of the following statements is correct? A. Increasing CO will increase K eq . B. Increasing temperature will increase K eq . C. Increasing temperature will decrease K eq . D. Decreasing Ni CO 4 will decrease K eq . R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 2 / 63 3. Consider the equilibrium... N2 (g)+3H2 (g) 2NH3 (g), K eq =64 A 1.0L container is filled with 0.28 mol N2 , 0.16 mol H2 and 0.54 mol NH3 . In which direction will the reaction proceed and what will happen to the pressure of the system? 4. Consider the following equilibrium... NH4NO2 (s) N2 (g)+2H2O(g) Which of the following correctly represents the H2 O at equilibrium? A. H2 O = K eq N2 1 K eq B. H2 O = 2 N2 C. H2 O = D. H2 O = 5. K eq NH4NO2 N2 K eq NH4NO2 N2 Consider the following equilibrium: 4NH3 (g) 5O2 (g) 4NO(g) 6H2O(g) energy Which of the following will cause the equilibrium to shift to the left? A. adding H2 O(g) B. removing some NO(g) C. increasing the volume D. decreasing the temperature R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 3 / 63 6. Consider the following equilibrium… 2NO(g) O2 (g) 2NO2 (g) energy When the volume of the container is increased, the equilibrium shifts to the… A. left and K eq decreases B. right and K eq increases C. left and K eq remains constant D. right and K eq remains constant 7. Consider the following equilibrium… 4HCl(g) O2 (g) 2H2O(g) 2Cl2 (g) energy The temperature of the equilibrium system is increased and a new equilibrium is established. The rates of the forward and reverse reactions for the new equilibrium compared to the original equilibrium have… 8. The value of K eq changes when… A. a catalyst is added B. the temperature changes C. the surface area changes D. the concentration of reactants changes R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 4 / 63 9. Consider the following equilibrium… PCl5 (g) PCl3 (g) Cl(g) A 1.00 L flask contains 0.0200 mol PCl5 , 0.0500 mol PCl3 and 0.0500 mol Cl2 at equilibrium. The value of K eq is… A. 0.125 B. 2.50 C. 5.00 D. 8.00 10. Consider the following equilibrium… N2 (g) 2O2 (g) 2NO2 (g) Equal moles of N2 and O2 are added, under certain conditions, to a closed container. Which of the following describes the changes in the reverse reaction which occur as the system proceeds toward equilibrium? 11. A chemical equilibrium is described as “dynamic” because… A. maximum randomness has been achieved B. the pressure and temperature do not change C. both reactants and products continue to form D. the concentrations of chemical species remain constant R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 5 / 63 12. Which of the following reactions results in an entropy increase? A. 2C(s) O2 (g) 2CO(g) B. N2 (g) 2H2 (g) N2H4 (l) C. 2SO2 (g) O2 (g) 2SO3 (g) D. Ag (aq) Cl (aq) AgCl(s) 13. Consider the following equilibrium: CH3 COOH(aq) H2O(l) CH3 COO (aq) H3 O (aq) heat A stress was applied at time t1 and the data was plotted on the following graph… The stress that was imposed at time t1 is the result of… A. the addition of HCl B. decreasing the temperature C. the addition of NaCH3 COO D. increasing the volume of the container R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 6 / 63 14. Consider the following potential energy diagram for an equilibrium system… When the temperature of the system is increased, the equilibrium shifts to the… A. left and the K eq increases B. left and the K eq decreases C. right and the K eq increases D. right and the K eq decreases 15. Consider the following equilibrium… 2O3 (g) 3O2 (g), K eq 65 Initially, 0.10 mole of O3 and 0.10 mole of O2 are placed in a 1.0 L container. Which of the following describes the changes in concentrations as the reaction proceeds toward equilibrium? R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 7 / 63 16. Which of the following applies to a chemical equilibrium? I. II. III. Forward and reverse reaction rates are equal Equilibrium can be achieved from either direction Macroscopic properties are constant A. I only B. I and II only C. II and III only D. I, II and III 17. A. B. C. D. In which of the following will the driving forces of minimum enthalpy and maximum entropy oppose one another? 2C(s) O2 (g) 2CO(g), H 221kJ 2N2 (g) O2 (g) 2N2O(g),ΔH 164kJ 18. 2CO(g) O2 (g) 2CO2 (g),ΔH 566kJ 4CO2 (g) 6H2O(g) 2C2H6 (g) 7O2 (g), H 3122kJ Ammonia, NH3 , is produced by the following reaction… N2 (g) 3H2 (g) 2NH3 (g) energy Which of the following would result in the highest concentration of ammonia at equilibrium? A. increasing the temperature and increasing the pressure B. decreasing the temperature and increasing the pressure C. increasing the temperature and decreasing the pressure D. decreasing the temperature and decreasing the pressure 19. Consider the following reaction… C(s) 2H2 (g) CH4 (g), H 74.8kJ Which of the following will cause an increase in the value of K eq ? A. increasing H2 B. decreasing the volume C. finely powdering the C(s) D. decreasing the temperature R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 8 / 63 20. Consider the following equilibrium… H2 (g) I2 (g) 2HI(g) At equilibrium H2 0.00220mol/L , I2 0.00220mol/L and HI 0.0156mol/L . The value of K eq is… A. 3.10x104 B. 1.99x102 C. 5.03x101 D. 3.22x103 21. Consider the following equilibrium… 2NOCl(g) 2NO(g) Cl2 (g) A flask of fixed volume is initially filled with NOCl(g) , NO(g) and Cl2 (g) . When equilibrium is reached, the pressure has increased. To reach equilibrium, the reaction proceeded to the… A. left because Trial K eq was less than K eq B. right because Trial K eq was less than K eq C. left because Trial K eq was greater than K eq D. right because Trial K eq was greater than K eq 22. A. B. C. D. In which of the following do both minimum enthalpy and maximum entropy factors favour the reactants? Cl2 (g) Cl2 (aq), H 25kJ C(s) H2O(l) CO(g) H2 (g), H 131kJ 2CO2 (g) 3H2O(g) C2H5 OH(l) 3O2 (g), H 1239kJ Na2CO3 (s) HCl(aq) 2NaCl(aq) CO2 (g) H2 O(l), H 28kJ R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 9 / 63 23. Consider the following equilibrium… H2 (g) I2 (g) 2HI(g) Which graph represents what happens when some HI is removed and a new equilibrium is established? 24. Consider the following equilibrium… CO(g) H2O(g) CO2 (g) H2 (g), H 41kJ What will cause a shift in the equilibrium? A. adding a catalyst B. changing volume C. adding an inert gas D. changing temperature R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 10 / 63 25. The equilibrium expression for a reaction is… K eq H 6 Bi3 H2 S 2 3 The reaction could be… A. 6H (aq) BiS(s) 2Bi3 (aq) 3H2S(g) B. 6H (aq) Bi2S3 (s) 2Bi3 (aq) 3H2S(g) C. 2Bi3 (aq) 3H2S(aq) Bi2S3 (s) 6H (aq) D. 2Bi3 (aq) 3H2S(aq) Bi2S3 (aq) 6H (aq) 26. Consider the following… PCl3 (g) Cl2 (g) PCl5 (g), K eq 0.45 at 227°C Initially, a 1.00L flask is filled with 0.100 mol PCl3 , 0.100 mol Cl2 , and 0.100 mol PCl5 at 227°C. Use K trial to predict the change in Cl2 as equilibrium is established. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 11 / 63 27. Consider the following equilibrium reaction: 2ICI(g) I2 (g) Cl2 (g) Some ICI is added to an empty flask. How do the reaction rates change as the system approaches equilibrium? A. B. C. D. 28. Forward rate increases increases decreases decreases Reverse rate increases decreases increases decreases In an equilibrium system, continuing microscopic changes indicate that the equilibrium is… A. dynamic B. complete C. exothermic D. spontaneous 29. Consider the following equilibrium… 4CuO(s) energy 2Cu2O(s) O2 (g) The equilibrium will shift to the right as a result of… A. adding CuO(s) B. removing O2 (g) C. adding a catalyst D. decreasing the temperature 30. Consider the following equilibrium… N2 (g) 3H2 (g) 2NH3 (g) The volume of the system is decreased. The equilibrium shifts… A. left since the reverse rate is greater than the forward rate B. left since the forward rate is greater than the reverse rate C. right since the reverse rate is greater than the forward rate D. right since the forward rate is greater than the reverse rate R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 12 / 63 31. Consider the following equilibrium… 2SO3 (g) 2SO2 (g) O2 (g), H 198kJ When the temperature is increased, the equilibrium will shift… A. left with K eq becoming larger B. right with K eq becoming larger C. left with K eq becoming smaller D. right with K eq becoming smaller 32. Starting with equal concentrations of reactants, which of the following will be closest to completion at equilibrium? A. CO(g) Cl2 (g) COCl2 (g), Keq 22 B. PCl3 (g) Cl2 (g) PCl5 (g), K eq 2.9x102 C. CO(g) Cl2 (g) COCl2 (g), K eq 4.5x109 D. CH3 O2 (g) NO2 (g) CH3 O2NO2 (g), K eq 2.1x1012 33. Consider the following equilibrium… 2COF2 (g) CO2 (g) CF4 (g) At equilibrium, a 1.00L container contains 7.07x104 mol COF2 , 1.00x103 mol CO2 , and 1.00x103 mol CF4 . What is the value of K eq ? A. 7.07x104 B. 1.41x103 C. 0.500 D. 2.00 R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 13 / 63 34. Consider the following reaction… 2ICI(g) I2 (g) Cl2 (g) A closed container is initially filled with ICI(g) . What are the changes in the rate of the forward reaction and I2 , as the system approaches equilibrium? 35. The entropy of a system is a term used to describe A. randomness B. heat content C. average kinetic energy D. stored chemical energy 36. Consider the following equilibrium… Cu2 (aq) blue 4Br colourless (aq) energy CuBr42- (aq) green Which of the following will cause this equilibrium to change from blue to green? A. adding NaBr(s) B. adding NaNO3 (s) C. adding a catalyst D. decreasing the temperature R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 14 / 63 37. Consider the following equilibrium: Ni(s) 4CO(g) Ni(CO)2 (l), H -160.8kJ Which of the following will cause this equilibrium to shift to the left? A. add some CO B. decrease the volume C. remove some Ni(CO)4 D. increase the temperature 38. Consider the following equilibrium… N2O4 (g) energy 2NO2 (g) Which of the following shows the relationship between concentration and time as a result of adding a catalyst at time t1 ? R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 15 / 63 39. Consider the following equilibrium… H2S(g) I2 (s) 2HI(g) S(s) What is the equilibrium expression for this reaction? HI A. K eq H2 S H2 S B. K eq 2 HI 2 HI S C. K eq H2SI2 H2SI2 D. K eq 2 HI S 2 40. Consider the following equilibrium… CO(g) H2O(g) CO2 (g) H2 (g), K eq 5.0 At equilibrium, the CO 0.20mol/L , H2 O 0.30mol/L , and H2 0.90mol/L . Calculate the equilibrium CO2 . A. B. C. D. 0.013mol/L 0.066mol/L 0.33mol/L 1.0mol/L R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 16 / 63 41. Consider the following… CO2 (g) CF4 (g) 2COF2 (g), K eq 0.50 In a reaction container the initial concentrations are… CO2 0.50mol/L , CF4 0.50mol/L , COF2 0.30mol/L To reach equilibrium, the reaction will proceed… A. left since Trial K eq < K eq B. left since Trial K eq > K eq C. right since Trial K eq < K eq D. right since Trial K eq > K eq 42. All chemical equilibriums must have… A. K eq 1 B. reactants products C. rate forward = rate reverse D. mass of reactants = mass of products 43. Consider the following equilibrium reaction… 4HCl(g) O2 (g) 2H2O(g) 2Cl2 (g) 111.4kJ For the forward reaction, how do enthalpy and entropy change? A. B. C. D. Enthalpy increases decreases increases decreases Entropy decreases decreases increases increases R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 17 / 63 44. Consider the following equilibrium… CH3 Cl(aq) OH (aq) CH3 OH(aq) Cl (aq) The equilibrium will shift to the left as a result of the addition of… A. B. C. D. HNO3 KNO3 NaOH CH3 Cl 45. Consider the following equilibrium at 25°C… Ni(s) 4CO(g) Ni(CO)4 (l) For this reaction… A. K eq CO 4 B. K eq 1 CO Ni(CO)4 C. K eq 4 CO NI Ni(CO)4 D. K eq 4 CO 46. 4 Consider the following equilibrium… 2COF2 (g) CO2 (g) CF4 (g), K eq 2.00 At equilibrium, CO2 0.050mol/L and CF4 0.050mol/L . What is COF2 at equilibrium? A. B. C. D. 0.0012mol/L 0.035mol/L 0.050mol/L 0.22mol/L R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 18 / 63 47. Consider the following equilibrium… H2 O(g) Cl2O(g) 2HOCl(g), K eq 0.0900 Initially, a 1.00L flask is filled with 0.100 mol of H2 O , 0.100 mol of Cl2 O and 0.100 mol of HOCl . As equilibrium is established, the reaction proceeds to the… A. left because Trial K eq > K eq B. left because Trial K eq < K eq C. right because Trial K eq > K eq D. right because Trial K eq < K eq 48. What will cause the value of K eq for an endothermic reaction to increase? A. increasing [products] B. decreasing [products] C. increasing the temperature D. decreasing the temperature 49. Consider the following equilibrium… N2 O4 (g) 2NO2 (g) An equilibrium mixture contains 4.0x102mol N2 O4 and 1.5x102mol NO2 in a 1.0 L flask. What is the value of K eq ? A. B. C. D. 5.6x103 3.8x101 7.5x101 1.8x102 50. Which of the factors below is not a condition necessary for equilibrium? A. a closed system B. a constant temperature C. equal forward and reverse reaction rates D. equal concentrations of reactants and products R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 19 / 63 51. In order for a chemical reaction to go to completion, how must the entropy and enthalpy change? 52. Consider the following equilibrium system… 2SO2 (g) O2 (g) 2SO3 (g),K eq 1.2x104 If additional SO2 is added to the system, what happens to the equilibrium and the value of K eq ? 53. Consider the following equilibrium system… N2 (g) 3H2 (g) 2NH3 (g) Determine the changes in reaction rates as a catalyst is added. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 20 / 63 54. Consider the following equilibrium system… 2KClO3 (s) 2KCl(s) 3O2 (g) Which of the following is the equilibrium constant expression? A. K eq O2 3 B. K eq 1 O2 2 KClO3 C. K eq 2 3 KCl O2 2 3 KCl O2 D. K eq 2 KClO3 55. 3 Consider the following equilibrium… CO2 (g) 2H2O(g) CH4 (g) 2O2 (g) Which of the options below indicates that the reactants are favoured? A. K eq is zero B. K eq is very large C. K eq is slightly less than 1 D. K eq is slightly greater than 1 56. Consider the following equilibrium… N2O4 (g) energy 2NO2 (g) How are K eq and N2 O4 affected by the addition of neon (an inert gas) into the container at constant volume. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 21 / 63 57. Consider the following equilibrium… Cl2 (g) 2NO(g) 2NOCl(g), K eq 5.0 At equilibrium, Cl2 1.0M and NO 2.0M . What is the NOCl at equilibrium? A. 0.80 M B. 0.89 M C. 4.5 M D. 10 M 58. For the equilibrium system below… Cu(s) 2Ag (aq) 2Ag(s) Cu2 (aq) We would know the system is at equilibrium because… A. Cu2 Ag B. 2 Cu2 Ag C. the mass of Cu(s) remains constant D. the mass of the entire system remains constant 59. For the reacting system… ? 2Li(s) 2H2 O(l) 2LiOH(aq) H2 (g), H 433kJ What will entropy and enthalpy factors favour? R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 22 / 63 60. Consider the following equilibrium… N2 (g) 3H2 (g) 2NH3 (g) If some Ne gas is added at a constant volume then how will N2 , H2 , and K eq be affected? 61. What is the effect of adding a catalyst to an equilibrium system? A. The value of Ea increases B. The value of K eq increases C. Forward and reverse rates increase D. The concentration of products increases 62. Consider the following equilibrium… 2CrO42 (aq) 2H (aq) Cr2O72 H2O(l) What is the K eq expression? 2 CrO4 2 H A. Cr2 O7 2 B. C. D. 2 Cr2 O7 2 2 CrO4 2 H Cr2 O72 2 2CrO42 2H Cr2 O7 2 H2 O 2 CrO4 2 H 2 R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 23 / 63 63. A container is initially filled with pure SO3 . After a period of time, the following equilibrium is established… 2SO2 (g) O2 (g) 2SO3 (g), K eq 7.0x1025 What does this equilibrium mixture contain? A. mostly products B. mostly reactants 3 2 C. reactants and products 5 5 D. equal amounts of reactants and products 64. Consider the following equilibrium… 2CO(g) O2 (g) 2CO2 (g), K eq 4.0x1010 What is the value of K eq for 2CO2 (g) 2CO(g) O2 (g) ? A. B. C. D. 4.0x1010 2.0x105 5.0x104 2.5x109 65. Consider the following equilibrium… H2 (g) Br2 (g) 2HBr(g), H 36kJ How could the value of K eq be increased? A. add H2 B. add HBr C. increase the pressure D. reduce the temperature R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 24 / 63 66. A student places some HI (g) into a closed reaction container and the following equilibrium is established... 2HI(g) I2 (g)+H2 (g) Which of the following describes the forward and reverse reaction rates? 67. Consider the equilibrium... H2 (g)+FeO(s) H2O(g)+Fe(s) The following chemicals are placed in separate 1.0 L containers. In which container(s) will the equilibrium be established? A. Container III only B. Container IV only C. Containers I and II only D. Containers III and IV only R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 25 / 63 68. Consider the following... energy+6CO2 (g)+6H2O(l) C6H12O6 (s)+6O2 g Which of the following describes how enthalpy and entropy change in the forward direction? 69. Consider the following system at equilibrium... energy+N2H6 CO2 (s) 2NH3 (g)+CO2 (g) Which of the following is correct when the volume of the system is increased? 70. Consider the following system at equilibrium... 2NO(g)+O2 (g) 2NO2 (g) Some O2 is added to the equilibrium. Which of the following describes how the forward and reverse reaction rates change as a new equilibrium is being established? R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 26 / 63 Consider the following PE diagram… 71. Identify the activation energy for the forward uncatalyzed reaction. A. 1 B. 2 C. 3 D. 4 72. In which of the following will entropy and enthalpy factors favour the establishment of an equilibrium? ? A. CaCO3 (s) 178kJ CaO(s) CO2 (g) ? MgCl2 (aq) H2 (g) 425kJ B. Mg(s) 2HCl(aq) ? C2H4 (g), H 52.3kJ C. 2C(s) 2H2 (g) ? 4CO2 (g) 6H2O(g),H 1560kJ D. 2C2H6 (g) 7O2 (g) 73. (A09062003) Consider the following equilibrium… CO(g) 2H2 (g) CH3OH(g), H 91kJ Which of the factors below would increase the concentration of CH3OH at equilibrium? A. an addition of CO B. an increase in the volume C. a decrease in the pressure D. an increase in the temperature R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 27 / 63 74. Consider the following equilibrium… PCl3 (g) Cl2 (g) PCl5 (g) If the volume of the system is decreased, how will the reaction rates in the new equilibrium compare with the rates in the original equilibrium? 75. Consider the following equilibrium… H2 (g) I2 (g) colourless purple 2HI(g) colourless , H 71.9kJ Which of the following would allow you to conclude that the system has reached equilibrium? A. The pressure remains constant. B. The reaction rates become zero. C. The colour intensity remains constant. D. The system shifts completely to the right. 76. Consider the following equilibrium… Fe2O3 (s) 3CO(g) 2Fe(s) 3CO2 (g) Identify the equilibrium constant expression. CO2 A. K eq 3 CO CO2 B. K eq CO 3 2 CO2 Fe C. K eq 3 CO Fe2O3 3 Fe2 O3 CO D. K eq 3 2 CO2 Fe 3 R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 28 / 63 77. Consider the following equilibrium system… 2NO(g) Cl2 (g) 2NOCl(g), H 77kJ In which direction will the equilibrium shift and what happens to the value of K eq when the temperature of the system is increased? 78. Consider the following equilibrium… CO(g) 2H2 (g) CH3OH(g) At equilibrium it was found that CO 0.105 mol/L , H2 0.250 mol/L and CH3OH 0.00261 mol/L . Which of the following is the equilibrium constant value? A. 9.94x102 B. 0.398 C. 2.51 D. 10.0 79. In a certain reaction H 136kJ and Ea 96kJ . Which of the following is true of its reverse reaction? A. The reverse reaction is exothermic and Ea 40J B. The reverse reaction is exothermic and Ea 40kJ C. The reverse reaction is endothermic and Ea 96kJ D. The reverse reaction is endothermic and Ea 232kJ R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 29 / 63 80. Two experiments were performed involving the following equilibrium. The temperature was the same in both experiments. H2 (g) I2 (g) 2HI(g) In experiment A, 1.0 M H2 and 1.0 M I2 were initially added to a flask and equilibrium was established. In experiment B, 2.0 M HI was initially added to a second flask and equilibrium was established. Which of the following statements is always true about the equilibrium concentrations? A. H2 equals HI in experiment A B. HI equals 2 H2 in experiment A C. HI in experiment A equals HI in experiment B D. HI in experiment A equals 81. A. B. C. D. 1 I2 in experiment B 2 Which of the following reactions is accompanied by an increase in enthalpy? 2NO(g) O2 (g) 2NO2 (g) 113kJ 2H2 (g) O2 (g) 484kJ 2H2O(g) 82. 2SO3 2SO2 (g) O2 (g), H 197kJ 4HCl(g) O2 (g) 2H2O(g) 2Cl(g), H 111.4kJ Two substances are mixed and no reaction occurs. With respect to enthalpy and entropy, which of the following could explain why no reaction occurs? R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 30 / 63 83. Consider the following reaction… N2 (g) 3H2 (g) 2NH3 (g) Which of the following diagrams represents what happens to the forward and reverse reaction rates when the catalyst Fe3 O4 is added? 84. Temperature is gradually decreased then held constant in an exothermic equilibrium. Which of the following represents the change in the reverse reaction rate? R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 31 / 63 85. If N2 O4 is placed in a flask at a constant temperature, which of the following is true as the system approaches equilibrium? N2 O4 (g) colourless 2NO2 (g) brown A. The colour gets darker as NO2 increases B. The colour gets lighter as NO2 decreases C. The colour gets darker as N2 O4 increases D. The colour gets lighter as N2 O4 decreases 86. The system above reaches equilibrium. Considering enthalpy and entropy factors, which of the following is true with respect to the forward reaction? N2 O4 (g) colourless 2NO2 (g) brown A. The entropy is increasing and the reaction is exothermic B. The entropy is decreasing and the reaction is exothermic C. The entropy is increasing and the reaction is endothermic D. The entropy is decreasing and the reaction is endothermic 87. In which of the following reactions do the tendencies for minimum enthalpy and maximum entropy both favour reactants? ? A. 3O2 (g) 2O3 (g),H 285kJ ? B. N2 (g) 3H2 (g) 2NH3 (g), H 92kJ ? Br2 (g) Cl2 (g), H 29.3kJ C. 2BrCl(g) ? D. CaCO3 (s) CaO(s) CO2 (g), H 175kJ R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 32 / 63 88. Consider the following equilibrium… CaCO3 (s) CaO(s) CO2 (g), H 175kJ Which of the following diagrams best represents the change in the concentration of CO2 as temperature is decreased at time t1 ? 89. The Haber Process is used to produce ammonia commercially according to the following equilibrium… N2 (g) 3H2 (g) 2NH3 (g) energy Which of the following conditions will produce the highest yield of ammonia? A. increase temperature and increase pressure B. increase temperature and decrease pressure C. decrease temperature and increase pressure D. decrease temperature and decrease pressure R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 33 / 63 90. Consider the following equilibrium… Cr2O72 (aq) 2OH (aq) 2CrO42 (aq) H2 O(l), Keq 4.14 The concentration of ions at equilibrium was measured at a specific temperature and found to be CrO72 0.100M and OH 0.020M . What is the equilibrium CrO42 A. 1.7x104M B. 3.1x103M C. 1.3x102M D. 2.0x101M 91. In which of the following equilibria does the concentration of reactants equal the concentration of products? A. N2 O4 (g) 2NO2 (g), K eq 0.71 B. H (aq) OH (aq) H2O(l), K eq 1.0x1014 C. CO2 (g) H2 (g) CO(g) H2O(g), K eq 0.279 D. SnO2 (s) 2H2 (g) Sn(s) 2H2O(g),K eq 1.00 92. Consider the following equilibrium… C(s) H2O(g) CO(g) H2 (g) At equilibrium 4.0x102 mol CO , 1.0x102 mol H2 O ,and 1.0x102 mol C were present in a 1.0 L container. What is the value of K eq ? A. 0.063 B. 0.16 C. 6.3 D. 16 R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 34 / 63 93. Consider the following equilibrium… 2COF2 (g) CO2 (g) CF4 (g) Initially, 0.12 M CO2 and 0.20 M CF4 are placed in a container. At equilibrium, it is found that the COF2 is 0.040 M. What is the value of K eq ? A. 0.089 B. 0.45 C. 8 0 D. 11 94. Which of the following represents the value for the activation energy of the forward reaction in an equilibrium system? A. Ea(forward) Ea(reverse) H B. Ea(forward) Ea(reverse) H C. Ea(forward) ΔH Ea(reverse) D. Ea(forward) ΔH Ea(reverse) 95. Consider the following equilibrium… CaCO3 (s) CaO(s) CO2 (g) In which of the flasks will this equilibrium be established? A. 1, 2, 3 only B. 1, 2, 4 only C. 1, 3, 4 only D. 3, 4 only R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 35 / 63 96. Which of the following forward reactions demonstrates decreasing enthalpy and increasing entropy? 1 ? A. Hg(l) O2 (g) HgO(s), H 91kJ 2 ? B. 2HCl(g) H2 (g) Cl2 (g), H 185kJ ? C. 2HgO(s) 2Hg(l) O2 (g),H 182kJ ? D. 2SO3 (g) 2SO2 (g) O2 (g), H 200kJ 97. Which of the following would cause the amount of NH3 at equilibrium to increase? 4NH3 (g) 3O2 (g) 2N2 (g) 6H2O(l), H 1530kJ A. an increase in O2 B. a decrease in volume C. a decrease in temperature D. an increase in temperature 98. What happens when O2 is added to the above system? 4NH3 (g) 3O2 (g) 2N2 (g) 6H2O(l), H 1530kJ R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 36 / 63 99. If some O2 is injected into the system, what happens to the forward and reverse reaction rates during the shift to re-establish equilibrium? 4NH3 (g) 3O2 (g) 2N2 (g) 6H2O(l), H 1530kJ 100. Consider the equilibrium expression K eq(01) for reaction 01… 1 SO2 (g) O2 (g) SO3 (g) 2 and the equilibrium expression K eq(02) for reaction 02… 2SO3 (g) O2 (g) 2SO2 (g) How is K eq(01) related to K eq(02) ? A. K eq(01) K eq(02) B. K eq(02) K eq(01) 2 1 C. K eq(02) K eq(01) 1 K eq(01) D. K eq(02) 2 R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 37 / 63 Written Questions 1. Consider the following equilibrium: H2 (g) I2 (g) 2HI(g), K eq 49 A 1.00 L container is initially filled with 0.180 moles of HI . Calculate the concentration of HI at equilibrium. (2 marks) 2. Consider the following diagram for a chemical system containing three substances represented by A, B and C: A. What feature of the graph indicates that the system reaches equilibrium? (1 mark) B. Write a balanced equation for the equilibrium reaction. (2 marks) C. Calculate K eq at equilibrium. (2 marks) R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 38 / 63 3. Describe how enthalpy and entropy change, in the forward direction, as an exothermic reaction reaches equilibrium. Explain your reasoning. (2 marks) 4. Consider the graph below representing the following equilibrium... CH3 CH2 CH2 CH3 (g) CH3 CH(CH3 )2 (g) n butane isobutane Data for the graph was obtained from various equilibrium mixtures. Calculate the value of K eq for the equilibrium. (2 marks) R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 39 / 63 5. Consider the following equilibrium system... N2 (g) 3H2 (g) 2NH3 (g) energy A 1.00 L container is filled with 5.0 mol NH3 and the system proceeds to equilibrium as indicated by the graph. A. Draw and label the graph for N2 and H2 . (2 marks) B. Calculate the K eq for N2 (g) 3H2 (g) 2NH3 (g) energy (2 marks) 6. State Le Chatelier’s Principle. (2 marks) 7. Consider the following equilibrium... 4HCl(g) O2 (g) 2H2O(g) 2Cl2 (g) energy A. How does the entropy change in the forward direction? Explain your reasoning. (1 mark) R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 40 / 63 B. How does the enthalpy change in the forward direction? Explain your reasoning. (1 mark) 8. Consider the following equilibrium... H2 (g) I2 (g) 2HI(g), K eq 1.2x102 A 2.0 L flask is filled with 0.10 mol HI . Calculate the concentration of H2 at equilibrium. (3 marks) 9. Consider the following equilibrium... Fe3 (aq) SCN (aq) FeSCN2 (aq) Initially, 50.0mL of 0.10M Fe3 SCN . At equilibrium, the concentration of FeSCN2 is found to be 0.050M. Calculate the K eq for the reaction. (4 marks) 10. Methanol, CH3 OH , is produced industrially by the following reaction... CO(g) 2H2 (g) CH3 OH(g) heat A. State two different methods of shifting the equilibrium to the right. (1 mark) B. In terms of rates, explain why these methods cause the equilibrium to shift to the right. (1 mark) R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 41 / 63 11. Consider the following equilibrium... H2 (g) I2 (g) 2HI(g) A 2.0L container is filled with 0.070 mol of H2 and 0.060 mol of I2 . Equilibrium is reached after 15.0 minutes at which time there is 0.060 mol of HI present. Sketch and label the graphs for the changes in concentrations of H2 , I2 and HI for the time period of 0 to 30.0 minutes. (3 marks) R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 42 / 63 12. Consider the observations for the following equilibrium... N2 O4 (g) 2NO2 (g) colourless brown A. Sketch the potential energy curve on the graph below for this equilibrium. (1 mark) B. Explain the colour change using Le Chatelier’s Principle. (1 mark) C. Other than changing temperature, what could be done to cause a shift to the left? (1 mark) R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 43 / 63 13. Consider the data obtained for the following equilibrium... Fe3 (aq) SCN (aq) FeSCN2 (aq) A. Calculate the FeSCN2 in experiment #2. (3 marks) 14. Consider the following reaction… Fe3 (aq) SCN (aq) FeSCN2 (aq) yellow colourless red When a few drops of 6.0 M NaOH is added to 25.0 mL of the above system, a precipitate of Fe OH3 forms and the solution turns pale yellow. A. Explain this colour change in terms of Le Chatelier’s Principle. (2 marks) B. Describe the effect on the rate of the reverse reaction as the color change occurs. (1 mark) 15. Consider the following equilibrium: 3I2 (g) 3F2 (g) 2IF2 (g) I4F2 (g) Initially, 2.00x101mol of I2 and 3.00x101mol of F2 and put into a 10.00L flask. At equilibrium, I4F2 is 2.00x103M . Calculate the K eq . (4 marks) R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 44 / 63 16. Consider the following equilibrium system: 2COF2 (g) CO2 (g) CF4 (g), K eq 2.00 A 2.00 L container is filled with 0.500 mol of COF2 . Calculate the COF2 at equilibrium. (5 marks) 17. Consider the following equilibrium system: Cu2 (aq) blue 4Br (aq) colourless CuBr42- (aq) green Cooling the equilibrium changes the colour from green to blue. What effect will the decrease in temperature have on K eq ? Explain, using Le Chatelier’s Principle. (2 marks) 18. A flask is initially filled with some HI . At equilibrium, the HI 0.80mol/L . What is the H2 at equilibrium? (3 marks) 2HI(g) H2 (g) I2 (g), K eq 0.25 19. Consider the following equilibrium system: 2NOCl(g) 2NO(g) Cl2 (g),K eq 1.6x105 A 1.00 L flask is filled with 0.20 mol NOCl , 0.10 mol NO and 0.10 mol Cl2 . State and show by calculation the direction in which the reaction proceeds to reach equilibrium. (4 marks) R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 45 / 63 20. Write four statements that apply to all chemical equilibrium systems. (2 marks) 21. Consider the following equilibrium system… H2 (g) Br2 (g) 2HBr(g), K eq 14.8 A closed container was initially filled with equal moles of H2 and Br2 . When equilibrium is reached, the HBr is 0.329 mol/L. What was the initial H2 ? (4 marks) 22. Consider the following graph for the reaction… H2 (g) I2 (g) 2HI(g) A. The temperature is increased at t1 and equilibrium is re-established at t 2 . On the above graph, sketch the line representing the HI between time t1 and t 3 . (1 mark) b. Calculate the value of K eq after t 2 . (2 marks) R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 46 / 63 23. Consider the following equilibrium system… 2SO2 (g) O2 (g) 2SO3 (g) A 1.00 L container is initially filled with 0.100 mol SO2 , 0.100 mol O2 . At equilibrium the O2 concentration is 0.060 mol/L. Calculate the value of K eq . (4 marks) 24. Consider the following equilibrium... 2NF2 (g) N2F2 (g) Equilibrium shifts to the right when the volume is decreased. Describe the changes in reaction rates that cause this shift to the right. (2 marks) 25. Consider the following... Initially, 0.200 mol of H2 and o.200 mol of I2 are added to an empty 2.00 L container. At equilibrium, the I2 is 0.020 mol/L . What is the value of K eq ? (4 marks) 26. State Le Chatelier’s Principle. (2 marks) 27. Consider the following... CH4 (g)+H2O(g) CO(g)+3H2 (g) Initially, 0.060 mol H2 O , 0.280 mol CO and 0.740 mol H2 are placed into a 4.00 L container. At equilibrium, the H2 is 0.200 mol/L . What is the value of K eq ? (4 marks) R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 47 / 63 28. Given the reacting system... H2 (g)+I2 (g) 2HI(g), K eq =64 Equal moles of H2 , I2 and HI are placed in a 1.0 L container. Use calculations to determine the direction the reaction will proceed in order to reach equilibrium. (3 marks) 29. Consider the following equilibrium system... H2 (g)+I2 (g) 2HI(g) The system is said to shift right as a result of the addition of extra H2 (g) . Describe the sequence of changes in both forward and reverse reaction rates as the system goes from the original equilibrium to the new equilibrium. (3 marks) 30. Consider the following equilibrium system... 2NO(g)+Cl2 (g) 2NOCl(g), Keq =8.5 A closed flask is found to contain 0.40 M NO(g) , 0.32 M Cl2 (g) and 5.6 M NOCl(g) . Use appropriate calculations to determine the direction the reaction proceeds to reach equilibrium. (3 marks) R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 48 / 63 Multiple Choice Question Answer Key 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 D C B A A C A B A A C A C B B D C B D C 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 B C B D C A C A B D B A D A A A D C A C 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 C C B A B B A C A D B C A A C A C C B D 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 C B A D D A D A C C B A A A C A D B D C 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 C B A B A C A A C C D B D A C D D C D D R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 49 / 63 Written Question Answer Key 1. 2. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 50 / 63 3. 4. 5. Consider R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 51 / 63 6. 7. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 52 / 63 8. Consider R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 53 / 63 9. 10. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 54 / 63 11. Consider R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 55 / 63 12. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 56 / 63 13. 14. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 57 / 63 15. 16. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 58 / 63 17. 18. 19. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 59 / 63 20. 21. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 60 / 63 22. 23. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 61 / 63 24. 25. 26. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 62 / 63 27. 28. R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 63 / 63 29. 30.
