Equilibrium Multiple ChoiceJanuary 1999 7. Consider the following graph: When equilibrium is reached, the rate of the forward reaction is A. 0.00 mol/min B. 0.25mol/min C. 1.0 mol/min D. 3.0 mol/min 8. Consider the following equilibrium: 2NO2 (g) N2O4 (g) + energy The equilibrium will shift to the left as a result of A. adding a catalyst. B. increasing the volume. C. removing some N2O4. D. decreasing the temperature. 9. Ethene, C2H4, can be produced in the following industrial system: C2H6 (g) + energy C2H4 (g) + H2 (g) The conditions that are necessary to maximize the equilibrium yield of C2H4 are A. low temperature and low pressure. B. low temperature and high pressure. C. high temperature and low pressure. D. high temperature and high pressure. 10. Consider the following equilibrium: H2 (g) + I2 (g) 2HI (g) The volume of the equilibrium system is increased and a new equilibrium is established. Compared to the rates in the original equilibrium, which of the following describes the rates of the forward and reverse reactions in the new equilibrium? 11. Consider the following equilibrium: N2 (g) + 3H2 (g) 2NH3 (g) + energy Certain conditions provide less than 10% yield of NH3 at equilibrium. Which of the following describes this equilibrium? 12. Which of the following best describes the relationship between Keq and temperature for an endothermic reaction? April 1999 7. Consider the following PE diagram for a reversible reaction: Which of the following describes this reaction? 8. Consider the following equilibrium: 2NO(g) + Br2(g) + energy 2NOBr(g) The equilibrium will shift to the left as a result of A. adding a catalyst. B. removing NOBr. C. increasing the volume. D. increasing the temperature. 9. Consider the following equilibrium: N2(g) + O2(g) + energy 2NO(g) When the temperature is increased, the equilibrium shifts to the A. left and Keq increases. B. left and Keq decreases. C. right and Keq increases. D. right and Keq decreases. 10. Consider the following equilibrium: 2CO(g) + O2(g) 2CO2 (g) + energy Some CO2 is added to the equilibrium system at constant volume and a new equilibrium is established. Compared to the original equilibrium, the rates of the forward and reverse reactions for the new equilibrium have 11. An indication that an equilibrium system favours the products is a A. large Keq . B. positive H. C. one step mechanism. D. low activation energy. 12. The relationship between Keq and the pressure of a gaseous equilibrium at constant temperature can be described by 13. Consider the following equilibrium: 2NO2(g) N2O4(g) A 1.00 L flask contains 0.030 mol NO2 and 0.040 mol N2O4 at equilibrium. The value of Keq is A. 0.023 B. 0.67 C. 1.3 D. 44 C. can be produced by the following: CO(g) + 2H2(g) CH3OH(g) + energy The conditions that are necessary to maximize the equilibrium yield of CH3OH are A.June 1999 7. adding a catalyst B. 10. B. Consider the following equilibrium: 2SO2(g) + O2(g) 2SO3(g) + energy Which of the following will cause this equilibrium to shift to the left? A. low temperature and low pressure. How are the forward and reverse reaction rates affected by the addition of the catalyst? . high temperature and high pressure. A catalyst is added to a system already at equilibrium. adding some SO2 C. low temperature and high pressure. Methanol. CH3OH. decreasing the temperature 9. increasing the volume D. high temperature and low pressure. D. Consider the following reaction: N2(g) + 3H2(g) 2NH3 (g) + energy Which of the following describes the changes in enthalpy and entropy as the reaction proceeds? 8. 4. Consider the following reaction: 2H2(g) + O2(g) 2H2O(l) What is the equilibrium constant expression for the reaction? A.7 101 mol .030 mol NO.0 102 mol D.11. 1.00 L flask contains 0.4 X 10-2 At equilibrium. The relationship between Keq and temperature for an exothermic reaction is represented by 13. a 1. Consider the following equilibrium: 2NOBr(g) 2NO(g) + Br2(g) Keq = 6. Keq= --------------- [H2]2[O2] 1 D.030 mol NOBr and 0.4 102 mol C. Keq = [H2]2[O2] [H2]2[O2] B. How many mol Br2 are present? A. 6.9 103 mol B. 3. Keq= --------------- [H2O]2 [H2O]2 C. Keq= ------------------ [H2]2[O2] 12. left and Keq remains constant. B. increasing the volume D. C. right and Keq increases. decreasing the temperature 9. adding H2O(g) B. right and Keq remains constant. At different conditions. the equilibrium shifts to the A. D. . the relationship between the forward and reverse rates of reaction in an equilibrium system can be represented by 8.August 1999 7. removing some NO (g) C. 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. Consider the following equilibrium: 2NO(g) + O2(g) 2NO2 (g) + energy When the volume of the container is increased. left and Keq decreases. 8. 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. 5.0500 mol PCl3 and 0. 13. The rates of the forward and reverse reactions for the new equilibrium compared to the original equilibrium have 11.00 . Consider the following reaction: 2Hg(g) + O2(g) 2HgO(s) The equilibrium constant expression for the reaction is 12.00 L flask contains 0.0200 mol PCl5. D. Consider the following equilibrium: PCl5(g) PCl3(g) + Cl2(g) A 1. B. 0. the temperature changes. the concentration of reactants changes. 2. 0. the surface area changes. a catalyst is added.50 C.125 B. The value of Keq changes when A. The value of Keq is A. C.0500 mol Cl2 at equilibrium.00 D.10. D. B.(aq) + H3O+ (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. N2(g) + 2H2(g) N2H4(l) C. 2C(s) + O2(g) 2CO(g) B. 9. Which of the following reactions results in an entropy increase? A. . the concentrations of chemical species remain constant. 2SO2(g) + O2(g) 2SO3(g) D. the addition of NaCH3COO. C. to a closed container. C. maximum randomness has been achieved. B. Consider the following equilibrium: N2(g) + 2O2(g) 2NO2(g) Equal moles of N2 and O2 are added. Consider the following equilibrium: CH3COOH(aq) + H2O(l) CH3COO. both reactants and products continue to form. under certain conditions. the addition of HCl. Ag+ (aq) + Cl. A chemical equilibrium is described as “dynamic” because A. decreasing the temperature.January 2000 7. the pressure and temperature do not change. Which of the following describes the changes in the reverse reaction which occur as the system proceeds toward equilibrium? 8.(aq) AgCl(s) 10. right and the Keq decreases. Which of the following describes the changes in concentrations as the reaction proceeds toward equilibrium? . left and the Keq increases. left and the Keq decreases. the equilibrium shifts to the A. What is the Keq expression for the following equilibrium? 3Fe(s) + 4H2O(g) Fe3O4(s) + 4H2(g) 13. D. 0. Consider the following potential energy diagram for an equilibrium system: When the temperature of the system is increased.D.0L container. C.10 mole of O2 are placed in a 1. increasing the volume of the container.10 mole of O3 and 0. 11. B. Consider the following equilibrium: 2O3(g) 3O2(g) Keq= 65 Initially. right and the Keq increases. 12. Ammonia. 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. KNO3 B. increasing the temperature and increasing the pressure B.(aq) + 3H2O(l) (yellow) (orange) An unknown solution is added to an orange equilibrium sample until the sample turns yellow. Which of the following applies to a chemical equilibrium? I. NH4NO3 D. Consider the following equilibrium: 2CrO4 2. Equilibrium can be achieved from either direction III.April 2000 7. II and III 8. I and II only C. NH3 . 2CO(g) + O2(g) 2CO2(g) H= -566kJ D. increasing the temperature and decreasing the pressure D. decreasing the temperature and decreasing the pressure . 2N2(g) + O2(g) 2N2O(g) H= +164kJ C. 2CO2(g) + 6H2O(g) 2C2H6(g) + 7O2(g) H= +3122kJ 9. Macroscopic properties are constant A. 2C(s) + O2(g) 2CO(g) H= -221kJ B. II and III only D. I only B.(aq) + 2H3O+ (aq) Cr2O7 2. In which of the following will the driving forces of minimum enthalpy and maximum entropy oppose one another? A. I. Forward and reverse reaction rates are equal II. decreasing the temperature and increasing the pressure C. NaOH C. The unknown solution could be A. CH3COOH 10. decreasing the temperature 13. When equilibrium is reached. The value of Keq is A.03 X 101 D.00220 mol/L. 5. [I2] = 0.00220 mol/L and [HI] = 0. To reach equilibrium. the pressure has increased.99 X 10-2 C. Consider the following reaction: C(s) + 2H2(g) CH4(g) H = -74. finely powdering the C (s) D. NO(g) and Cl2(g) . C.10 X 10-4 B.8KJ Which of the following will cause an increase in the value of Keq? A. .11. 1. 3. the reaction proceeded to the A. left because Trial Keq was less than Keq. 3. What is the Keq expression for the following reaction? SnO2(s) + 2CO(g) Sn(s) + 2CO2(g) 12. Consider the following equilibrium: H2(g) + I2(g) 2HI(g) At equilibrium [H2] = 0. Consider the following equilibrium: 2NOCl(g) 2NO(g) + Cl2(g) A flask of fixed volume is initially filled with NOCl(g). decreasing the volume C. right because Trial Keq was less than Keq.0156mol/L.22 X 103 June 2000 7. increasing [H2] B. B. left because Trial Keq was greater than Keq . Na2CO3(s) + HCl (aq) 2NaCl (aq) + CO2(g) + H2O(l) H= -28kJ 9. changing temperature 11. In which of the following do both minimum enthalpy and maximum entropy factors favour the reactants? A. Cl2(g) Cl2(aq) H= -25 kJ B. The equilibrium expression for a reaction is [H+]6 Keq = ------------------- [Bi3+]2[H2S]3 The reaction could be A. 6H+ (aq) + Bi2S3 (s) 2Bi 3+ (aq) + 3H2S(g) C. changing volume C. 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? 10. 2Bi 3+ (aq) + 3H2S (aq) Bi2S3(s) + 6H+(aq) . Consider the following equilibrium: CO(g) + H2O(g) CO2(g) + H2(g) H= -41kJ What will cause a shift in the equilibrium? A. 2CO2(g) + 3H2O(g) C2H5OH(l) + 3O2 H= +1239kJ D. C(s) + H2O(l) CO(g) + H2(g) H= +131kJ C. adding a catalyst B.D. 6H+ + BiS(s) 2Bi 3+ (aq) + 3H2S(g) B. right because Trial Keq was greater than Keq . 8. adding an inert gas D. 0 moles of gases present. 4. The macroscopic properties are constant.4 X 10-3 mol/L B. 6. Consider the following equilibrium: 2O3(g) 3O2(g) Keq = 36 What is the concentration of O3 when the equilibrium concentration Of O2 is 6. endothermic and the Keq has decreased.0 X 10-2 mol/L? A. 9.(aq) + 6H2O(l) (pink) (blue) When the temperature is increased. B. Forward and reverse reaction rates are equal.0 X 10-2 mol/L C.0 X 10-2 mo/L D. Based on this observation. Which of the following does not apply to all chemical equilibrium systems? A.0 X 10-2 mol/L August 2000 7. exothermic and the Keq has decreased. When equilibrium is reached. exothermic and the Keq has increased. 2. 8. endothermic and the Keq has increased. The reaction proceeded right because the Trial Keq > Keq D. There are equal concentrations of reactants and products. C. Initially there was a total of 5. They are closed. the reaction is A. 13. the solution turns a dark blue. The reaction proceeded left because the Trial Keq < Keq C.D. CoCl42. The reaction proceeded left because the Trial Keq > Keq B. Consider the following equilibrium: Co(H2O)6 2+ (aq) + 4Cl. D. The reaction proceeded right because the Trial Keq < Keq . D. Which of the following explains this observation? A. C. there is a total of 6. 2Bi 3+ (aq) + 3H2S (aq) Bi2S3 (aq) + 6H+ (aq) 12.0 moles of gases present. B. NO and Cl2. Consider the following equilibrium: 2NOCl(g) 2NO (g) + Cl2(g) A flask is filled with NOCl. decreasing the temperature.0 .9.0 What is the value Keq for the reaction rewritten as: 2HI (g) H2(g) + I2(g) Keq = ? A. –50. decreasing the volume by increasing the pressure. adding a catalyst. Consider the following equilibrium: 2NO2(g) N2O4 (g) + energy The number of moles of NO2 at equilibrium could be increased by A. 0. C.0 B.0200 C. 50.0 D. 11. adding N2O4 B. increases increases B. decreases increases D. 25. D. decreases decreases 10. Consider the following reaction: C3H8 (g) + 5O2(g) 3CO2(g) + 4H2O(g) H = -2202kJ Which of the following applies to the forward reaction? Entropy Enthalpy A. increases decreases C. Consider the following equilibrium: H2 (g) + I2(g) 2HI(g) Keq = 50. What is the Keq expression for Sb3+ (aq) + Cl-(aq) + H2O(l) SbOCl (s) + 2H+ (aq) 12. increasing increasing B. . rates that are continuing to change II. adding a catalyst. 0. decreasing increasing 9. II only B.22 mol/L B. 0. A.13. III only C.43 mol/L D. 0. decreasing the temperature. D. increasing the volume. 0. adding some NO (g).29 mol/L C. equal concentrations of products and reactants A. C. From the following.50 mol/L. decreasing decreasing D. I and II only D. All chemical equilibriums have: I. Calculate the equilibrium Concentration of N2O4 (g). select the situation where both enthalpy and entropy favour the reaction toward products: Enthalpy Entropy A. an equilibrium constant expression III. increasing decreasing C.58 mol/L January 2001 7. B. Consider the following equilibrium: 2NO(g) + Br2(g) 2NOBr(g) + energy The equilibrium will shift to the left as a result of A. Consider the following equilibrium: 2NO2(g) N2O4 (g) Keq = 1. I and III only 8.15 The equilibrium concentration of NO2 is 0. Which of the following best describes the equilibrium reaction and the change in Keq? A. N2 (g) + O2(g) 2NO(g) Keq= 1. decreased increased C. SO2(g) + NO2(g) SO3 (g) + NO(g) Keq= 3. exothermic and Keq decreases C. endothermic and Keq increases D. Consider the following equilibrium reaction: N2O4(g) 2NO2(g) At time t1. exothermic and Keq increases B. heat is applied to the system. How have the rates been affected? Rate (forward) Rate (reverse) A.0X10-31 12.4 C. which of the following equilibrium systems most favours the reactants? A. endothermic and Keq decreases . Starting with equal moles of reactants. decreased decreased D.4 B. CO(g) + H2O(g) CO2(g) + H2(g) Keq= 31. did not change did not change 11. increased decreased B. Consider the following equilibrium: PCl3(g) + 3NH3(g) P(NH2)3 (g) + 3HCl(g) The volume of the equilibrium system is increased and a new equilibrium is established.10. H2(g) + I2(g) 2HI(g) Keq= 10 D. spontaneous. 0. C. C.100mol Cl2. decreases decreases 8. . April 2001 7. and 0. increases decreases C. Consider the following equilibrium reaction: 2ICl(g) I2(g) + Cl2(g) Some ICl is added to an empty flask. exothermic.13. Consider the following equilibrium: 4CuO(s) + energy 2Cu2O(s) + O2(g) The equilibrium will shift to the right as a result of A. increases increases B. B. In an equilibrium system. complete. dynamic. decreases increases D.100mol PCl3. adding a catalyst. How do the reaction rates change as the system approaches equilibrium? Forward rate Reverse rate A. B. a 1. removing O2 (g). D. 9. D. continuing microscopic changes indicate that the equilibrium is A. decreasing the temperature.100mol PCl5 at 227°C. Use KTrial to predict the change in [Cl2] as equilibrium is established. adding CuO (s).45 at 227°C Initially.00L flask is filled with 0. Consider the following: PCl3(g) + Cl2(g) PCl5(g) Keq = 0. 07 X 10-4 mol COF2. CO(g) + Cl2(g) COCl2(g) Keq=4.07 X 10-4 B. and 1.9 X 10-2 C. which of the following will be closest to completion at equilibrium? A. left with Keq becoming smaller. 12.5 X 10 –9 D.1 X 10 -12 13.500 D. 11. the equilibrium will shift A. CH3O2 (g) + NO2(g) CH3O2NO2(g) Keq=2. 1.00 .00L container contains 7. 1. right with Keq becoming larger. C. right with Keq becoming smaller. PCl3(g) + Cl2(g) PCl5(g) Keq= 2. The equilibrium shifts A.00 X 10-3 mol CF4. C. 7. right since the forward rate is greater than the reverse rate. Starting with equal concentrations of reactants. 2. a 1. D. Consider the following equilibrium: N2(g) + 3H2(g) 2NH3(g) The volume of the system is decreased. D. Consider the following equilibrium: 2COF2(g) CO2(g) + CF4(g) At equilibrium. left since the forward rate is greater than the reverse rate. 0.00 X 10-3 mol CO2. left since the reverse rate is greater than the forward rate. right since the reverse rate is greater than the forward rate. Consider the following equilibrium: 2SO3(g) 2SO2(g) + O2(g) kJ When the temperature is increased. B. CO(g) + Cl2(g) COCl2(g) Keq=22 B.10. B. What is the value of Keq? A.41 X 10-3 C. left with Keq becoming larger. randomness. Consider the following equilibrium: Cu2+ (aq) + 4Br-(aq) + energy CuBr4 2-(aq) Blue colourless green Which of the following will cause this equilibrium to change from blue to green? A. heat content. C. decreasing the temperature 10. adding NaNO3 (s) C.June 2001 7. 9. add some CO B. adding NaBr (s) B. Consider the following reaction: 2ICl(g) I2(g) + Cl2(g) A closed container is initially filled with ICl (g). What are the changes in the rate of the forward reaction and [I2]. increase the temperature . Consider the following equilibrium: Ni(s) + 4CO(g) Ni(CO)2(l) kJ Which of the following will cause this equilibrium to shift to the left? A. stored chemical energy. D. remove some Ni(CO)4 D. adding a catalyst D. The entropy of a system is a term used to describe A. decrease the volume C. as the system approaches equilibrium? 8. average kinetic energy. B. 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 t = 1? 12. and [H2]= 0.013 mol/L C.30mol/L. Calculate the equilibrium [CO2]. Keq=--------------- [HI]2 [HI]2[S] C.20mol/L.90mol/L. Keq=--------------- [H2S]P[I2] [H2S]P[I2] D.11. 0. A.33 mol/L .0 At equilibrium. 0. [H2O]= 0. Consider the following equilibrium: CO(g) + H2O(g) CO2(g) + H2(g) Keq = 5. Consider the following equilibrium: H2S(g) + I2(s) 2HI(g) + S(s) What is the equilibrium expression for this reaction? [HI]2 A Keq=--------------- [H2S] [H2S] B. Keq=--------------- [HI]2[S] 13. the [CO]= 0. B. All chemical equilibriums must have A. decreases decreases C. D. [COF2]= 0. decreases increases 9. rate forward = rate reverse. right since Trial Keq > K eq August 2001 7. CH3Cl . Consider the following: CO2(g) + CF4(g) 2COF2(g) Keq= 0.30 mol/L To reach equilibrium. Consider the following equilibrium reaction: 4HCl(g) + O2(g) 2H2O(g) + 2Cl2(g) + 111. right since Trial Keq < K eq D. [reactants]=[products]. increases decreases B. C. HNO3 B. 1.(aq) CH3OH(aq) + Cl-(aq) The equilibrium will shift to the left as a result of the addition of A.066 mol/L D.50mol/L. KNO3 C.0mol/L 14.50mol/L. mass of reactants = mass of products. 8.50 In a reaction container the initial concentrations are: [CO2]= 0. how do enthalpy and entropy change? Enthalpy Entropy A. the reaction will proceed A. 0.4kJ For the forward reaction. Consider the following equilibrium: CH3Cl(aq) + OH. Keq = 1 B. left since Trial Keq > K eq C. increases increases D. [CF4]= 0. left since Trial Keq < K eq B. NaOH D. left because KTrial < K eq C. 0. 0. Keq= -------------- [CO]4 [Ni(CO)4(l)] C. Consider the following equilibrium at 25°C : Ni(s) + 4CO(g) Ni(CO)4(l) For this reaction A.0900 Initially.100mol of Cl2O and 0. a 1. left because KTrial > K eq B.100mol of H2O.100mol of HOCl. What t is [COF2] at equilibrium? A.00L flask is filled with 0. right because KTrial > K eq D. Consider the following equilibrium: H2O(g) + Cl2O(g) 2HOCl(g) Keq= 0.10.050 mol/L D. As equilibrium is established.0012 mol/L B.22 mol/L 12. 0.050mol/L and [CF4]=0.050mol/L.00 At equilibrium. Consider the following equilibrium: 2COF2(g) CO2(g) + CF4(g) Keq=2. Keq = [CO]4 1 B. Keq= ---------------- [CO]4 [Ni] [Ni(CO)4(l)] D. Keq= ---------------- [CO]4 11. 0. the reaction proceeds to the A.035 mol/L C. 0. right because KTrial < K eq . [CO2]=0. SO3 is added to an empty flask. decrease [CO2] . decrease [H2] . decrease [H2O] . Consider the following: 2SO2(g) + O2(g) 2SO3(g) Initially. increase [H2] . increase [H2O] C. Consider the following reaction: N2(g) + 3H2(g) 2NH3(g) + energy What positions do minimum enthalpy and maximum entropy tend toward? Use the following equilibrium equation to answer questions 9 and 10. increase [CO] B. How do the rate of the forward reaction and [SO3] change as the system proceeds to equilibrium? 8. CO2(g) + H2(g) H2O(g) + CO(g) 9.January 2002 7. increase [CO2] . decrease [CO] D. Which two stresses will each cause the equilibrium to shift to the left? A. increasing the temperature D. At equilibrium there is 0. decreasing the temperature . What will cause the Keq for an exothermic reaction to increase? A. What is the [H2] at this equilibrium? A. 0. 4NO2(aq) + 6H2O(l) 4NH3(g) + 7O2(g) D.030mol N2 present. 4NO2(g) + 6H2O(g) 4NH3(g) + 7O2(g) 13. some NH3 is placed into a 1. 0.060 mol/L D. 0. 0. decreasing [products] C. increasing [reactants] B.030 mol/L C.010 mol/L B. Consider the following: 2NH3 (g) N2(g) + 3H2(g) Initially.090 mol/L 12. 4NH3(g) + 7O2(g) 4NO2(g) + 6H2O(g) B. 4NH3(aq) + 7O2(g) 4NO2(aq) + 6H2O(l) C. Which of the following graphs represents the forward rate of reaction when H2O(g) is added to the above equilibrium at time t = 1 ? 11.0L container.10. Which reaction has the following equilibrium expression? [NO2]4[H2O]6 Keq=----------------- [NH3]4[O2]7 A. Which of the following two stresses will each cause the system to shift to the right? A. HI is added to an empty flask. increase temperature. decrease temperature. increase temperature. How do the rates of the forward and reverse reactions change as the system proceeds to equilibrium? 8. decrease temperature. Consider the following: H2(g) + I2(g) 2HI(g) Initially. increase volume B. decrease volume D. decrease volume . 2CO(g) + O2(g) 2CO2(g) + energy 9. increase volume C. Consider the following reaction: 2H2O(l) + energy 2H2 (g) + O2(g) Determine the enthalpy and entropy changes for the above reaction? Use the following equilibrium equation to answer questions 9 and 10.April 2002 7. 030 mol/L D. there is 0. Consider the following: 2SO2(g) + O2(g) 2SO3(g) Initially. 0. Keq=-------------------. Keq= --------------- [H2O][CO2] [CaCO3][HF]2 [H2O][CO2] [CaF2] [H2O][CO2] B. increasing the surface area C. 0. What is the [SO2] at equilibrium? A.10. decreasing the temperature .010 mol/L B. 0.020 mol O2 present. Which of the following shows the forward rate of reaction when the temperature of the system is increased at time t = 1 ? 11.030mol O2 are placed into a 1. 0. adding a catalyst B. Keq=---------------. D.0L container. What will cause the Keq for an endothermic reaction to decrease? A. What is the equilibrium expression for the following system? CaCO3(s) + 2HF(g) CaF2(s) + H2O(g) + CO2(g) [HF]2 [H2O][CO2] A. 0. At equilibrium. C. Keq= ---------------------- [HF]2 [CaCO3][HF]2 13.020 mol/L C.040 mol/L 12.030mol SO2 and 0. increasing the temperature D. increase temperature.June 2002 7) Consider the following : 2HBr(g) ⇄ H2(g) + Br2(g) Initially. HBr is added to an empty flask. How do the rate of the forward reaction and the [HBr] change as the system proceeds to equilibrium? Forward Rate [HBr] A. 2SO2(g) + O2(g) ⇄ 2SO3(g) + energy 8) Which of the following two stresses will each cause the system to shift to the right? A. increase temperature. decrease [O2] B. Decreases Increases C. decrease [SO3] D. Increases Decreases Use the following equilibrium equation to answer questions 8 and 9. Decreases Decreases B. increase [SO3] C. decrease temperature. decrease temperature. Increases Increases D. increase [SO2] 9) Which of the following graphs shows the reverse rate of reaction when a catalyst is added to the equilibrium at time = t1? . 080 mol D. products reactants C. 0.090 mol 12) What is the equilibrium expression for the following system? 4Fe(s) + 3O2(g) ⇄ 2Fe2O3(s) A.060 mol B. some HI is placed into a 1. Keq = [O2]3 1 B. 0. Keq = [O2]3 [Fe2O3]2 C. At equilibrium there is 0.010 mol H2. 0.010 mol I2 and 0.070 mol C.10) Consider the following: ? 2N2(g) + O2(g) + energy ⇄ 2N2O(g) What positions do minimum enthalpy and maximum entropy tend toward? Minimum Maximum Enthalpy Entropy A. reactants reactants 11) Consider the following: H2(g) + I2(g) ⇄ 2HI(g) Initially. 0. Keq = [Fe]4[O2]3 [2Fe2O3] D. reactants products D. keq = [4Fe][3O2] 13) What will cause the value of Keq for an endothermic reaction to increase? . 0. products products B.070 mol HI present.0L container. How many moles of HI were initially added to the container? A. 0L flask.8 × 102 August 2002 7) Consider the following: 2NH3(g) ⇄ N2(g) +3H2(g) Initially. 5.6 × 10-3 B. A.0 × 10-2 mol N2O4 and 1. decreasing the temperature 14) Consider the following equilibrium: N2O4(g) ⇄ 2NO2(g) An equilibrium mixture contains 4. Increases Increase B. decreasing [products] C.8 × 10-1 C. Reactants Reactants Use the following equilibrium equation to answer questions 9 and 10. Increases Decreases C. Reactants Products D. 1. Products Products B. increasing [products] B. 7. What is the value of Keq? A. How do the rates of the forward and Reverse reactions change as the system proceeds to equilibrium? Forward Rate Reverse Rate A. increasing the temperature D. NH3 is added to an empty flask. decreases decreases 8) Consider the following: ? H2(g) + Br2(l) ⇄ 2HBr(g) + energy What positions do minimum enthalpy and maximum entropy tend toward? Minimum Enthalpy Maximum Entropy A.5 × 10-2 mol NO2 In a 1. Decreases Increases D.5 × 10-1 D. H2(g) + I2(g) ⇄ 2HI(g) + energy . 3. Products Reactants C. increase temperature 10) Which of the following shows the reverse rate of reaction when the volume is decreased at time = t1? 11) Consider the following: 2SO3(g) ⇄ 2SO2(g) + O2(g) Initially. 0. increase [H2] C. some SO3 is placed into a 3. decrease volume D.9) Which of the following stresses will not cause s shift in equilibrium? A.030 mol/L 12) Which reaction has the following equilibrium expression? .030 mol SO2 present. What is the [O2] at equilibrium? A. 0. 0.015 mol/L D.0050 mol/L B. 0. decrease [I2] B.010 mol/L C.0L container. At equilibrium there is 0. PCl5(g) ⇄ PCl3(g) + Cl2(l) 13) What will cause the value of Keq for an exothermic reaction to decrease? A. increasing the temperature C.0 × 101 C. PCl3(g) + Cl2(l) ⇄ PCl5(g) C. 50 × 103 D. 2. increasing the pressure B. a constant temperature C. how must the entropy and enthalpy change? .0L container. 1. decreasing the temperature D. PCl5(g) ⇄ PCl3(g) + Cl2(g) D. 5.0 × 10-2 mol HI in a 1. equal concentrations of reactants and products 8) In order for a chemical reaction to go to completion.0 × 10-3 mol H2. 2. [PCl5] Keq = [PCl3][Cl2] A. equal forward and reverse reaction rates D.0 × 10-2 B. PCl3(g) + Cl2(g) ⇄ PCl5(g) B.0 × 10-3 mol I2 And 1.0 × 104 January 2003 7) Which of the factors below is not a condition necessary for equilibrium? A. decreasing the surface area 14) Consider the following equilibrium: H2(g) + I2(g) ⇄ 2HI(g) An equilibrium mixture contains 1. What is the value of Keq? A. a closed system B. Entropy Enthalpy A.2 × 104 If additional SO2 is added to the system. Decreases Decreases 11) Consider the following equilibrium system: 2KClO3(s) ⇄ 2KCl(s) + 3O2(g) . Increases Increases B. Shifts right No change D. Forward Rate Reverse Rate A. Shifts left Decreases B. Increases Increases B. Increases Decreases C. what happens to the equilibrium and The value of Keq? Equilibrium Keq A. No change No change 10) Consider the following equilibrium system: N2(g) + 3H2(g) ⇄ 2NH3(g) Determine the changes in reaction rates as a catalyst is added. Decreases Increases D. Increases Decreases C. Shifts right Increases C. Decreases Decreases 9) Consider the following equilibrium system: 2SO2(g) + O2(g) ⇄ 2SO3(g) Keq = 1. Decrease Increases D. 13) Consider the following equilibrium: N2O4(g) + energy ⇄ 2NO2(g) How are Keq is [N2O4] affected by the addition of Ne (an inert gas) into the Container at constant volume.0 At equilibrium. Keq [N2O4] A. D. Keq = [O2]3 [KClO3]2 C. C. Keq = [KCl]2[O2]3 [KCl]2[O2]3 D. [Cl2] = 1.0M and [NO] = 2. decreases increases 14) Consider the following equilibrium: Cl2(g) + 2NO(g) ⇄ 2NOCl(g) Keq = 5. Keq is slightly less than 1. Keq is very large. No change Increases C. What is the [NOCl] at equilibrium? . B. No change No change B.0M. Which of the following is the equilibrium constant expression? A. Keq is slightly greater than 1. Keq = [KClO3]2 12) Consider the following equilibrium: CO2(g) + 2H2O(g) ⇄ CH4(g) + 2O2(g) Which of the options below indicates that the reactants are favoured? A. Keq is aero. Increases Decreases D. Keq = [O2]3 1 B. 4.80 M B. 10 M April 2003 7) For the equilibrium system below: Cu(s) + 2Ag+(aq) ⇄ 2Ag(s) + Cu+2(aq) We would know the system is at equilibrium because A.89 M C.5 M D. D. Products Reactants B. Reactants Reactants D. 0. the mass of Cu(s) remains constant. the mass of the entire system remains constant. 8) For the reacting system: 2Li(s) + 2H2O(l) → 2LiOH(aq) + H2(g) ∆H = -433 KJ What will entropy and enthalpy factors favour? Entropy Enthalpy A. [H2] and Keq . 2[Cu+2] = [Ag+] C. A. Products Products C. [Cu+2] = [Ag+] B. 0. Reactants Products 9) Consider the following equilibrium: N2(g) + 3H2(g) ⇄ 2NH3(g) If some Ne gas is added at a constant volume then how will [N2]. [2CrO42-][2H+] [Cr2O72-][H2O] D. [CrO42-]2[H+]2 [Cr2O72-] C. [CrO42-]2[H+]2 12) A container is initially filled with pure SO3. Increases Increases Decreases B. The value of Ea increases. The concentration of products increases. After a period of time. Decreases Increases Does not change D. be affected? [N2] [H2] Keq A. D. Does not change Does not change Does not change 10) What is the effect of adding a catalyst to an equilibrium system? A. the following equilibrium is established: 2SO2(g) + O2(g) ⇄ 2SO3(g) Keq = 7. C.0 × 1025 What does this equilibrium mixture contain? . B. [Cr2O72-] [Cr2O72-] B. 11) Consider the following equilibrium: 2CrO42-(aq) + 2H+(aq) ⇄ Cr2O72-(aq) + H2O(l) What is the Keq expression? [CrO42-]2[H+]2 A. The value of Keq increases. Decreases Decreases Increases C. Forward and reverse rates increase. mostly products B. increase the pressure D. 2.0 × 10-5 C. 5. mostly reactants 3 2 C. reduce the temperature June 2003 7) Consider the following PE diagram: . 4. 13) Consider the following equilibrium: 2CO(g) + O2(g) ⇄ 2CO2(g) Keq = 4. add H2 B.0 × 10-10 B.0 × 104 D. A. equal amounts of reactants and products. 2. reactants and products 5 5 D.5 × 109 14) Consider the following equilibrium: H2(g) + Br2(g) ⇄ 2HBr(g) ∆H = -36KJ How could the value of Keq be increased? A. add HBr C.0 × 10-10 What is the value of Keq for 2CO2(g) ⇄ 2CO(g) + O2(g) ? A. an increase in the volume C. 4 8) In which of the following will entropy and enthalpy factors favour the establishment of an equilibrium? ? A. 3 D. an increase in the temperature 10) Consider the following equilibrium: PCl3(g) + Cl2(g) ⇄ PCl5(g) If the volume of the system is decreased. an addition of CO B. 2C(s) + 2H2(g) → C2H4(g) ∆H = +52. 2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(g) ∆H = -1560 KJ 9) 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. how will the reaction rates in the new . CaCO3(s) + 178KJ → CaO(s) + CO2(g) ? B. 1 B. Identify the activation energy for the forward uncatalysed reaction. Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) + 425KJ ? C. A.3KJ ? D. a decrease in the pressure D. 2 C. [CO2]3 A. B. D. Keq = [Fe2O3][CO]3 [Fe2O3][CO]3 D. The pressure remains constant. Increases Increases B. 12) Consider the following equilibrium: Fe2O3(s) + 3CO(g) ⇄ 2Fe(s) + 3CO2(g) Identify the equilibrium constant expression.Keq = [CO2]3[Fe]2 13) Consider the following equilibrium system: 2NO(g) + Cl2(g) ⇄ 2NOCl(g) ∆H = -77KJ In which direction will the equilibrium shifts and what happens to the value of . equilibrium compare with the rates in the original equilibrium? Forward Rate Reverse Rate A.9KJ Colourless purple colourless Which of the following would allow you to conclude that the system has reached equilibrium? A. The system shifts completely to the right. C. Decreases Decreases D. The reaction rates become zero. Increases Decreases C. Keq = [CO]3 [CO2] B. Keq = [CO] [CO2]3[Fe]2 C. The colour intensity remains constant. Decreases Increases 11) Consider the following equilibrium: H2(g) + I2(g) ⇄ 2HI(g) ∆H = -71. 51 D. Left Increases D. Right Decreases C. How will this shift affect the concentrations of the other gases? .94 × 10-2 B. Decrease Increase D. 0.0 August 2003 7) Consider the following equilibrium: H2(g) + I2(g) ⇄ 2HI(g) How will the forward and reverse equilibrium reaction rates change when additional H2 is added to the system? Forward Rate Reverse Rate A. Left Decreases 14) Consider the following equilibrium: CO(g) + 2H2(g) ⇄ CH3OH(g) At equilibrium it was found that [CO] = 0. 2. 9. 10. Which of the following is the equilibrium constant value? A. Keq when the temperature of the system is increased? Shift Keq A.105 mol/L. [H2] = 0. Right Increases B. No change No change 8) Consider the following system at equilibrium: H2O(g) + CO(g) ⇄ CO2(g) + H2(g) This equilibrium will shift right as the result of the addition of some extra H2O.398 C. Increase Decrease C.00261 mol/L.250 mol/L and [CH3OH] = 0. Increase Increase B. a temperature increase C. Decreases Increases Increases D. the addition for more N2(g) 10) Consider the following equilibrium: N2O4(g) + energy ⇄ 2NO2(g) Which of the following graphs shows the result of increasing the temperature at time t1? 11) Consider the following equilibrium and the table of experimental data: N2O4(g) ⇄ 2NO2(g) Initial Equilibrium [N2O4] [NO2] [N2O4] [NO2] . [CO] [CO2] [H2] A. a pressure decrease B. Increases Increases Decreases C. Increases Decreases Decreases B. Deceases Decreases Increases 9) Consider the following equilibrium: N2(g) + 3H2(g) ⇄ 2NH3(g) Which of the following factors will not alter the position of equilibrium? A. the presence of a catalyst D. 0000 0.2 × 10-4 C.0337 0. N2O(g) + NO2(g) ⇄ 3NO(g) Keq = 4. B. C.0429 0. N2O4(g) ⇄ 2NO2(g) Keq = 4.0200 0. 14) Consider the following system: 2CO(g) + O2(g) ⇄ 2CO2(g) A container is initially filled with CO and O2. decrease increase Answer Key January 1999 April 1999 June 1999 August 1999 7 C 7 D 7 C 7 A 8 B 8 C 8 C 8 A 9 C 9 C 9 C 9 C 10 A 10 A 10 A 10 A 11 D 11 A 11 D 11 A 12 C 12 D 12 A 12 B 13 C 13 D 13 B 13 A . 4. How will the [CO] and [CO2] change as the system reaches equilibrium? [CO] [CO2] A.64 × 10-3 B. 7.3 × 10-18 B. SO2(g) + NO2(g) ⇄ NO(g) + SO3(g) Keq = 85 13) Consider the following equilibrium: N2(g) + 3H2(g) ⇄ 2NH3(g) What is the final result of adding some NH3 gas to the system at constant volume? A. Keq increases.0600 0.5 D. 3. Decrease Decrease D. [NH3] decreases.42 × 10-1 D. 2H2O(g) ⇄ 2H2(g) + O2(g) Keq = 7.71 × 10-1 C. [H2] decreases. D. Keq remains unchanged.16 × 102 12) Which of the following is least likely to favour the formation of products? A.0125 Trial 2 0. Increase Decrease B. Trial 1 0. Increase Increase C.0400 0. 2.0141 Which of the following represents the Keq value? A. January 2000 April 2000 June 2000 August 2000 7 A 7 D 7 B 7 D 8 C 8 C 8 C 8 D 9 A 9 B 9 B 9 B 10 C 10 B 10 D 10 A 11 B 11 B 11 C 11 A 12 C 12 D 12 C 12 B 13 B 13 C 13 A 13 B January 2001 April 2001 June 2001 August 2001 7 A 7 C 7 A 7 C 8 D 8 A 8 A 8 B 9 C 9 B 9 A 9 A 10 C 10 D 10 D 10 B 11 D 11 B 11 C 11 B 12 C 12 A 12 A 12 A 13 A 13 D 13 C 14 C January 2002 April 2002 June 2002 August 2002 7 D 7 B 7 A 7 C 8 D 8 C 8 D 8 A 9 B 9 D 9 B 9 C 10 C 10 B 10 D 10 C 11 D 11 A 11 D 11 A 12 A 12 B 12 B 12 A 13 D 13 D 13 C 13 B 14 A 14 B January 2003 April 2003 June 2003 August 2003 7 D 7 C 7 B 7 A 8 B 8 B 8 A 8 C 9 C 9 D 9 A 9 C 10 A 10 C 10 A 10 A 11 A 11 B 11 C 11 A 12 C 12 A 12 A 12 A 13 A 13 D 13 D 13 D 14 C 14 D 14 B 14 D .