13_Test_Bank

Chemistry, 6e (McMurry/Fay) Chapter 13 Chemical Equilibrium 13.1 Multiple-Choice Questions 1) Which one of the following statements does not describe the equilibrium state? A) Equilibrium is dynamic and there is no net conversion to reactants and products. B) The concentration of the reactants is equal to the concentration of the products. C) The concentration of the reactants and products reach a constant level. D) The rate of the forward reaction is equal to the rate of the reverse reaction. Answer: B Topic: Section 13.1 The Equilibrium State 2) The equilibrium equation is also known as the law of A) coefficients. B) constant concentration. C) dynamic equilibrium. D) mass action. Answer: D Topic: Section 13.2 The Equilibrium Constant Kc 3) Which of the following statements is false regarding the equilibrium constant, Kc? A) Kc for a reaction at a particular temperature always has the same value. B) Kc for the reverse reaction is the negative of Kc for the forward reaction. C) The numerical value of Kc depends on the form of the balanced equation. D) When quoting Kc it is customary to omit units. Answer: B Topic: Section 13.2 The Equilibrium Constant Kc 4) Which statement about the equilibrium constant is true? The value of Kc A) changes as product concentration changes. B) changes as reactant concentration changes. C) changes as temperature changes. D) never changes. Answer: C Topic: Section 13.2 The Equilibrium Constant Kc 5) If Kc is the equilibrium constant for a forward reaction what is Kc´ for the reverse reaction? A) - Kc B) Kc C) (Kc)-1 D) none of these Answer: C Topic: Section 13.2 The Equilibrium Constant Kc 1 Copyright © 2012 Pearson Education, Inc. 6) If Kc is the equilibrium constant for a forward reaction, 2 A⇌ B, what is Kc´ for the reaction 4 A⇌ 2B? 1 A) Kc 2 B) Kc C) 2 Kc D) (Kc)2 Answer: D Topic: Section 13.2 The Equilibrium Constant Kc 7) Write the equilibrium equation for the forward reaction: 2 CH4 (g) + 3 O2 (g) ⇌ 2 CO (g) + 4 H2O (g) 2[CO] + 4[H 2O] A) Kc = 2[CH 4 ] + 3[O2 ] 2[CH 4 ] + 3[O2 ] B) Kc = 2[CO] + 4[H 2O] [CO]2[H 2O]4 C) Kc = [CH 4 ]2 [O2 ]3 [CH 4 ]2 + [O2 ]3 D) Kc = [CO]2 + [H 2O]4 Answer: C Topic: Section 13.2 The Equilibrium Constant Kc 8) Write the equilibrium equation for the reverse reaction: 2 CH4 (g) + 3 O2 (g) ⇌ 2 CO (g) + 4 H2O (g) 2[CO] + 4[H 2O] A) Kc´ = 2[CH 4 ] + 3[O2 ] 2[CO4 ] + 3[O2 ] B) Kc´ = 2[CO] + 4[H 2O] [CO]2 [H 2O]4 C) Kc´ = [CH 4 ]2 [H 2O]4 [CH 4 ]2 + [O2 ]3 D) Kc´ = [CO]2 + [H 2O]4 Answer: D Topic: Section 13.2 The Equilibrium Constant Kc 2 Copyright © 2012 Pearson Education, Inc. 9) Nitric oxide reacts with oxygen to form nitrogen dioxide: 2 NO(g) + O2(g) ⇌ 2 NO2(g) What is Kc for the forward reaction if the equilibrium concentration of NO is 0.200 M, O2 is 0.100 M, and NO2 is 0.250 M at 25°C? A) 8.00 × 10-2 B) 6.41 × 10-2 C) 12.5 D) 15.6 Answer: D Topic: Section 13.2 The Equilibrium Constant Kc 10) Nitric oxide reacts with oxygen to form nitrogen dioxide: 2 NO(g) + O2(g) ⇌ 2 NO2(g) What is Kc' for the reverse reaction if the equilibrium concentration of NO is 0.300 M, O2 is 0.200 M, and NO2 is 0.530 M at 25°C? A) 0.0340 B) 0.0641 C) 0.624 D) 15.6 Answer: B Topic: Section 13.2 The Equilibrium Constant Kc 11) A mixture of carbon monoxide, hydrogen, and methanol is at equilibrium. The balanced chemical equation is: CO(g) + 2H2(g) ⇌ CH3OH(g). At 250°C, the mixture contains 0.0960 M CO, 0.191 M H2, and 0.150 M CH3OH. What is the value for Kc? A) 2.33 × 10-2 B) 0.244 C) 4.09 D) 42.8 Answer: D Topic: Section 13.2 The Equilibrium Constant Kc 12) Given the reaction: 2 HI ⇌ H2 + I2. If Kc' for the reverse reaction is 1.85 × 10-2 at 425°C, what is Kc for the forward reaction at the same temperature? A) -1.85 × 10-2 B) 1.85 × 10-2 C) 3.70 × 10-2 D) 54.1 Answer: D Topic: Section 13.2 The Equilibrium Constant Kc 3 Copyright © 2012 Pearson Education, Inc. 13) For the reaction: N2(g) + 2 O2(g) ⇌ 2 NO2(g), Kc = 8.3 × 10-10 at 25°C. What is the concentration of N2 gas at equilibrium when the concentration of NO2 is twice the concentration of O2 gas? A) 2.1 × 10-10 M B) 4.2 × 10-10 M C) 2.4 × 109 M D) 4.8 × 109 M Answer: D Topic: Section 13.2 The Equilibrium Constant Kc 14) If Kc = 7.04 × 10-2 for the reaction: 2 HBr(g) ⇌ H2(g) + Br2(g), what is the value of Kc for the reaction: 1/2 H2(g) + 1/2 Br2(g) == HBr(g)? A) 3.52 × 10-2 B) 0.265 C) 3.77 D) 28.4 Answer: C Topic: Section 13.2 The Equilibrium Constant Kc 15) If Kc equals 0.11 at 25°C for the reaction: N2O4(g) ⇌ 2 NO2(g), what is Kc for the reaction: NO2(g) ⇌ 1/2 N2O4(g)? A) 0.33 B) 3.0 C) 4.5 D) 9.1 Answer: B Topic: Section 13.2 The Equilibrium Constant Kc 16) Which one of the following statements about the equilibrium constant, Kp, is false? A) Δn is equal to the sum of the coefficients of the gaseous products minus the sum of the coefficients of the gaseous reactants. B) The relationship between Kp and Kc is: Kp = Kc (RT)Δn C) The units for Kp are usually omitted. D) Total pressures are used in the equilibrium equation in place of molar concentrations. Answer: D Topic: Section 13.3 The Equilibrium Constant Kp 17) Kp is related to Kc by the equation Kp = Kc (RT)n. What is the value of n for the reaction below? NH4NO3(s) ⇌ N2O(g) + 2 H2O(g) A) -2 B) -1 C) +1 D) +2 Answer: D Topic: Section 13.3 The Equilibrium Constant Kp 4 Copyright © 2012 Pearson Education, Inc. 18) What is the equilibrium equation for the reaction: NH4NO3(s) ⇌ N2O(g) + 2 H2O(g)? A) Kp = [N2O] B) Kp = [N2O][H2O] C) Kp = [N2O][H2O]2 2 D) Kp = [N 2O][H 2O] [NH 4 NO3 ] Answer: C Topic: Section 13. .3 The Equilibrium Constant Kp 20) Write the equilibrium equation for the reverse reaction: 2 CH4(g) + 3 O2(g) ⇌ 2 CO(g) + 4 H2O(g) [PCH ]2 [PO ]3 4 2 '= A) Kp 2 [P [PCO ] H O ]4 2 [PCO ]2[PH O ]4 2 B) Kp' = 2[P ]3 [PCH ] O 4 2 2[PCO ] + 4[PH O ] 2 C) Kp' = 2[PCH ] + 3[PO ] 4 2 2[PCH ] + 3[PO ] 4 2 D) Kp' = 2[PCO ] + 4[PH O ] 2 Answer: A Topic: Section 13.3 The Equilibrium Constant Kp 5 Copyright © 2012 Pearson Education.3 The Equilibrium Constant Kp 19) Write the equilibrium equation for the forward reaction: 2 CH4(g) + 3 O2(g) ⇌ 2 CO(g) + 4 H2O(g) [PCH ]2 [PO ]3 4 2 A) Kp = 2 [P [PCO ] H O ]4 2 2 [P [PCO ] H O ]4 2 B) Kp= 2[P ]3 [PCH ] O 4 2 C) Kp = D) Kp = 2[PCO ] + 4[PH O ] 2 2[PCH ] + 3[PO ] 4 2 2[PCH ] + 3[PO ] 4 2 2[PCO ] + 4[PH O ] 2 Answer: B Topic: Section 13. Inc. 3 The Equilibrium Constant Kp 22) What is true about the relationship of Kp and Kc for the reaction: 2 CH4(g) + 3 O2(g) ⇌ 2 CO(g) + 4 H2O(g)? A) Kp < Kc B) Kp = Kc C) Kp > Kc D) Kp and Kc are not related.3 The Equilibrium Constant Kp 23) The oxidation of sulfur dioxide by oxygen to sulfur trioxide has been implicated as an important step in the formation of acid rain: 2 SO2(g) + O2(g) ⇌ 2 SO3(g).3 The Equilibrium Constant Kp 24) Given the reaction at a certain temperature: 2 HI(g) ⇌ H2(g) + I2(g). What is the value of Kp for the reaction: 2 N2(g) + 6 H2(g) ⇌ 4 NH3(g)? A) 4. and the partial pressures for H2 and I2 are 0. Inc.79 D) 8.8 × 10-3 atm. the partial pressure of HI is 1. A) 3.2 × 10-4 B) 5.3 × 10-4 C) 6.6 × 101 C) 3. O2.21) Kp = 1.1 × 103 D) 3.10 atm each.5 × 103 at 400°C for the reaction 2 NH3(g) ⇌ N2(g) + 3 H2(g).102 atm.7 × 10-4 D) 2.3 × 106 Answer: A Topic: Section 13. Answer: C Topic: Section 13. and SO3 are 0. . 0.11 Answer: B Topic: Section 13. If the equilibrium partial pressures of SO2. At equilibrium.564 atm.42 C) 5.3 The Equilibrium Constant Kp 6 Copyright © 2012 Pearson Education. and 0.1 × 104 Answer: C Topic: Section 13.292 B) 3. what is Kp at that temperature? A) 0.333 atm respectively at 1000 K. Find Kp at that temperature.4 × 10-7 B) 3. 50 B) 1.5 × 103 at 400°C.2 × 1031 B) 9. If Kp is 1.25 atm at equilibrium.0 x 1033 at 25°C. then find Kp at the same temperature. If the partial pressure of ammonia is 1.7 × 1032 C) 2.5 × 103 D) 4.4 × 106 atm Answer: B Topic: Section 13.3 The Equilibrium Constant Kp 27) The decomposition of ammonia is: 2 NH3(g) = N2(g) + 3 H2(g).0 × 1033 D) 4.15 atm? A) 2.1 × 103 atm D) 4.6 × 106 Answer: A Topic: Section 13. for the following reaction: H2(g) + Cl2(g) ⇌ 2 HCl(g). If Kc = 1.6 × 10-3 atm and the partial pressures of N2 and H2 are each 0.4 C) 1.10 atm and H2 is 0.2 × 10-2 B) 8.2 × 10-7 atm B) 4.9 × 1034 Answer: C Topic: Section 13.25) If Kc = 2.8 at 250°C. . Inc.3 The Equilibrium Constant Kp 7 Copyright © 2012 Pearson Education. what is the value for Kc at 400°C for the forward reaction? A) 0.3 The Equilibrium Constant Kp 26) Phosphorus pentachloride decomposes to phosphorus trichloride and chlorine gas at elevated temperatures by the following reaction: PCl5(g) ⇌ PCl3(g) + Cl2(g).7 × 10-4 atm C) 2.3 The Equilibrium Constant Kp 28) The decomposition of ammonia is: 2 NH3(g) ⇌ N2(g) + 3 H2(g). A) 8. What is the value of Kp at the same temperature? A) 4.8 × 10-2 C) 65 D) 77 Answer: D Topic: Section 13. what is the partial pressure of ammonia at equilibrium when N2 is 0. 4 Heterogeneous Equilibria 8 Copyright © 2012 Pearson Education. Inc. gases A) I.150 mol of Br2. III Answer: A Topic: Section 13. IV C) III.0 × 10-3 atm.29) The decomposition of ammonia is: 2 NH3(g) ⇌ N2(g) + 3 H2(g).2 × 10-4 B) -1.28 × 102 D) 1.20 atm.6 × 103 C) 6. aqueous solutions IV. What is the value of Kp for the reaction below? 2 NO(g) + Br2(g) ⇌ 2 NOBr(g) A) 2. 0. what is the value for Kp' at 400°C for the reverse reaction? A) -6.2 × 10-4 D) 1. and 0. II B) I. and the pressures of N2 and H2 are each 0. If the pressure of ammonia is 1.56 B) 62.5 C) 1. pure solids III. which of the following phases are not included in the equilibrium constant expression? I.53 × 103 Answer: A Topic: Section 13.3 The Equilibrium Constant Kp 31) As a rule. pure liquids II. . IV D) II.100 mol of NO.4 Heterogeneous Equilibria 32) Which equilibrium below is homogeneous? A) BaSO4(s) ⇌ Ba2+(aq) + SO42-(aq) B) 2 H2O2(l) ⇌ 2 H2O(l) + O2(g) C) NH4NO3(s) ⇌ N2O(g) + 2 H2O(g) D) 2 CO(g) + O2(g) ⇌ 2 CO2(g) Answer: D Topic: Section 13.250 mol of NOBr at 25°C.50 L vessel contains an equilibrium mixture of 0.6 × 103 Answer: C Topic: Section 13.3 The Equilibrium Constant Kp 30) A 1. 4 Heterogeneous Equilibria 34) What is the equilibrium equation for the following reaction? C2H4 (g) + 3 O2 (g) ⇌ 2 CO2 (g) + 2 H2O (l) [PCO ]2[PH O ]2 2 2 A) Kp = [PC H ][PO ]3 2 4 2 [PC H ][PO ]3 2 4 2 B) Kp = [PCO ]2 2 [PC H ][PO ]3 2 4 2 C) Kp = 2[P [PCO ] H O ]2 2 2 [PCO ]2 2 D) Kp = [PC H ][PO ]3 2 4 2 Answer: D Topic: Section 13. .] + C) Kc = [H3O ][HCOO ] [HCOOH] [HCOOH] D) Kc = [H3O+ ][HCOO.] A) Kc = 3 [HCOOH][H 2O] [HCOOH][H 2O] B) Kc = [H3O+ ][HCOO.33) What is the equilibrium equation for the dissociation of formic acid in water? HCOOH (aq) + H2O (l) ⇌ H3O+ (aq) + HCOO. Inc.(aq) [H O+ ][HCOO.4 Heterogeneous Equilibria 9 Copyright © 2012 Pearson Education.] Answer: C Topic: Section 13. 6 × 10-7 B) 1.6 × 10-5 C) 6.3 × 106 Answer: B Topic: Section 13. [Pb2+] = 1. Inc.] B) Kc = 3 [H 2O]2 [H 2O]2 C) Kc = [H3O+ ][OH.] D) Kc = [H3O+] [OH–] Answer: D Topic: Section 13.2 × 10-2 M at equilibrium? (The molar mass of PbCl2(s) is 278 g/mol and its density is 5. .35) What is the equilibrium equation for the following reaction? FeS(s) + 2 H3O+ (aq) ⇌ Fe2+(aq) + H2S (aq) + 2 H2O (l) [Fe2+ ][H 2S][H 2O]2 A) Kc = [FeS][H3O+ ]2 [Fe2+ ][H 2S][H 2O]2 B) Kc = [H3O+ ]2 [Fe2+ ][H 2S] C) Kc = [FeS][H3O+ ]2 [Fe2+ ][H 2S] D) Kc = [H3O + ]2 Answer: D Topic: Section 13.50 grams.4 Heterogeneous Equilibria 37) What is the value for Kc for the following reaction: PbCl2(s) ⇌ Pb2+(aq) + 2 Cl-(aq). if PbCl2(s) = 1.) A) 7.85 g/cm3.6 × 10-2 M and [Cl-] = 3.2 × 104 D) 1.4 Heterogeneous Equilibria 36) What is the equilibrium equation for the following reaction? 2 H2O (l) ⇌ H3O+ (aq) + OH– (aq) [H O+ ][OH.] A) Kc = 3 [H 2O] [H O+ ][OH.4 Heterogeneous Equilibria 10 Copyright © 2012 Pearson Education. Answer: C Topic: Section 13.4 Heterogeneous Equilibria 39) For which one of the following reactions will Kc = Kp? A) CO(g) + 2 H2(g) ⇌ CH3OH(g) B) ZnO(s) + CO(g) ⇌ Zn(s) + CO2(g) C) 2 O3(g) ⇌ 3 O2(g) D) COCl2(g) ⇌ CO(g) + Cl2(g) Answer: B Topic: Section 13. which of the equations below could represent the reaction at 25°C? A) A(g) + B(s) ⇌ 3 C(g) B) A(l) + 2 B(g) ⇌ 2 C(g) C) B(g) ⇌ C(l) + D(l) D) A(g) ⇌ 2 C(s) + D(g) Answer: A Topic: Section 13.4 Heterogeneous Equilibria 40) If Kc = 0. The molar mass and density of Hg(l) is 201 g/mol. Inc. and 1.38) What is the equilibrium constant. Kp = 0. for the reaction: 2 Hg(l) + O2(g) ⇌ 2 HgO(s) if the amounts of reactants and products at equilibrium are: 1.46 × 103 Answer: C Topic: Section 13. C) The reaction is favored in the reverse direction.00 g of HgO(s).) A) 6.45 at 250°C.0105 and Kc = 0.4 Heterogeneous Equilibria 42) For the reaction.6 g/mL. A(g) + 2 B(g) ⇌ 2 C(g).60 M O2(g)? (The molar mass and density of HgO(s) is 217 g/mol. and Kp = 538 for a hypothetical reaction.00 mL of Hg(l). 2. D) The value of Kp will be larger than the value for Kc.4 Heterogeneous Equilibria 41) Given the hypothetical reaction: 2 A(s) + x B(g) ⇌ 3 C(g). and 13. .5 Using the Equilibrium Constant 11 Copyright © 2012 Pearson Education. Kc = 1 × 10-10 at 25°C. Kc.66 × 10-2 C) 0.10 g/cm3. and 1. What is the value of the coefficient x? A) 1 B) 2 C) 3 D) 4 Answer: D Topic: Section 13.900.625 D) 1.85 × 10-4 B) 4. Which of the following statements is true? A) Δn = +1 B) The concentration of the products is greater than the concentration of the reactants. 40 at 25°C for the isomerization reaction: cis-2-butene ⇌ trans-2-butene. B) [O2] will increase.5 Using the Equilibrium Constant 44) For the reaction: 4 HCl(g) + O2(g) ⇌ 2 Cl2(g) + 2 H2O(l). C) not at equilibrium and will shift to the left to achieve an equilibrium state. Answer: A Topic: Section 13. Inc. the system is A) at equilibrium. D) not at equilibrium and will shift to the right to achieve an equilibrium state.43 × 10-12? A) Increasing the temperature will not change the value of Kc. B) There are appreciable concentrations of both reactants and products.45 M. C) [Cl2] will decrease. Answer: C Topic: Section 13. C) The reaction proceeds hardly at all towards completion. D) The system is not at equilibrium and will remain in an unequilibrated state. Kp. B) It will shift right. C) The system is already at equilibrium. If initial concentrations are [SO2] = 1.100. D) The reaction proceeds nearly all the way to completion.80 M. . equals 3. If a flask initially contains 1. If the reaction quotient is 0. which of the following statements is not correct? A) [HCl] will increase.43) Which statement is true for a reaction with Kc equal to 2.20 M.00 at 1300 K for the reaction: 2 SO2(g) + O2(g) ⇌ 2 SO3(g). and [SO3] = 1. the equilibrium constant is 0. Answer: B Topic: Section 13.5 Using the Equilibrium Constant 45) The equilibrium constant is equal to 5. Answer: D Topic: Section 13.5 Using the Equilibrium Constant 12 Copyright © 2012 Pearson Education.5 Using the Equilibrium Constant 46) The equilibrium constant. B) not at equilibrium and will remain in an unequilibrated state.00 atm of each gas. [O2] = 0.063 at 400 K. in what direction will the system shift to reach equilibrium? A) It will shift left. D) [H2O] will increase. C) is already at equilibrium. and NOBr are mixed.4 × 102 for the reaction: 2 CO(g) + O2(g) ⇌ 2 CO2(g).8 × 10-6 M B) 2. O2 and CO2 at a certain temperature contains 0.200 M and 0. Answer: B Topic: Section 13. The system A) will shift left. the concentration of NOBr increases. bromine and nitric oxide react to form nitrosyl bromide: Br2(g) + 2 NO(g) ⇌ 2 NOBr(g). Kc.5 Using the Equilibrium Constant 48) At a certain temperature. Which statement below is true? A) Kc < 36 B) Kc > 36 C) Kc < 90 D) Kc > 90 Answer: C Topic: Section 13. bromine and nitric oxide react to form nitrosyl bromide: Br2(g) + 2 NO(g) ⇌ 2 NOBr(g). NO.5 Using the Equilibrium Constant 50) An equilibrium mixture of CO. predict the direction the reaction will shift if the initial concentrations of C6H12 and MCP are 0.2 × 10-3 M C) 9. . Answer: A Topic: Section 13.47) Cyclohexane (C6H12) undergoes a molecular rearrangement in the presence of AlCl3 to form methylcyclopentane (MCP) according to the equation: C6H12 ⇌ MCP If Kc = 0.1 × 10-1 M Answer: B Topic: Section 13.010 mol Br2 is mixed with 0.143 at 25°C for this reaction. D) is not at equilibrium and will remain in an unequilibrated state. Inc.025 mol NO and 0. At this temperature.3 × 10-2 M D) 3. equals 1.5 Using the Equilibrium Constant 49) At a certain temperature.100 M.5 Using the Equilibrium Constant 13 Copyright © 2012 Pearson Education.0015 M O2. B) will shift right. When initial amounts of Br2.50 L flask. What is the equilibrium concentration of CO? A) 4. When 0.015 mol NOBr in a 2. the concentration of NOBr decreases. respectively.0010 M CO2 and 0. Which statement below is true? A) Kc < Q B) Kc > Q C) Kc = Q D) More information is needed to make a statement about Kc. 50 M and the product is 0. Kc equals 1.82 M and [product] = 0.57 at 25°C and the initial concentration of the reactant is 0.51) At a certain temperature.24 M B) [reactant] = 0. If the initial pressures of butane and isobutane are 10.44 M D) [reactant] = 0.76 M and [product] = 0. Inc.5 Using the Equilibrium Constant 53) The following two isomers of C3H7NO exist in equilibrium with each other in solution: If Kc = 0. .400 mol of CO2 and 0.100 mol of O2 at equilibrium.169 mol C) 0. how many moles of CO are also present in the flask? A) 0. respectively. what are the pressures of the two gases at equilibrium? A) P(butane) = 0.40 atm Answer: A Topic: Section 13. what are the concentrations at equilibrium? A) [reactant] = 0.70 M.50-L flask contains 0. If a 2.6 atm and P(isobutane) = 0.6 atm B) P(butane) = 0.38 atm and P(isobutane) = 9.0114 mol Answer: B Topic: Section 13.43 M and [product] = 0.4 × 102 for the reaction: 2 CO(g) + O2(g) ⇌ 2 CO2(g).107 mol D) 0.5 Using the Equilibrium Constant 52) For the isomerization reaction: butane ⇌ isobutane Kp equals 25 at 500°C.67 M and [product] = 0.47 M Answer: C Topic: Section 13.38 M C) [reactant] = 0.40 atm and P(isobutane) = 10.422 mol B) 0.5 Using the Equilibrium Constant 14 Copyright © 2012 Pearson Education. atm and 0.38 atm D) P(butane) = 10 atm and P(isobutane) = 0.0 atm. atm C) P(butane) = 9. 250 M PCl5 is added to a flask. respectively. P(trans-2-butene) = 0.018 M Answer: C Topic: Section 13. what is the equilibrium pressure of each gas? A) P(cis-2-butene) = 0. equals 3.5 Using the Equilibrium Constant 55) At a certain temperature the equilibrium constant.25 M. P(trans-2-butene) = 0.75 mol of I2 and 0.11 for the reaction: 2 ICl(g) ⇌ I2(g) + Cl2(g).5 Using the Equilibrium Constant 56) The equilibrium constant.282 and [CH3C5H9] = 0.162 M C) [C6H12] = 0.0-L flask? A) 0.75 mol of Cl2 are initially mixed in a 2.048 atm. what are the equilibrium concentrations of each gas? A) [PCl5] = 0.5 Using the Equilibrium Constant 15 Copyright © 2012 Pearson Education.165 atm C) P(cis-2-butene) = 0.27 M. P(trans-2-butene) = 0.40 for the isomerization reaction: cis-2-butene ⇌ trans-2-butene. [PCl3] = 1.80 M D) [PCl5] = 2. [Cl2] = 2. Inc. [PCl3] = 2.138 and [CH3C5H9] = 0. If Kc = 1.80 M. [Cl2] = 0. P(trans-2-butene) = 0.23 M B) 0.290 atm Answer: D Topic: Section 13.125 atm of trans-2-butene. If a flask initially contains 0.474 M. [Cl2] = 0.222 M.56 Answer: C Topic: Section 13. . What is the equilibrium concentration of ICl if 0.54) Cyclohexane (C6H12) undergoes a molecular rearrangement in the presence of AlCl3 to form methylcyclopentane (CH3C5H9) according to the equation: C6H12 ⇌ CH3C5H9 If Kc = 0.474 M C) [PCl5] = 1.143 at 25°C for this reaction. [PCl3] = 0.074 atm.02 M. 0.02 M Answer: A Topic: Section 13.262 M and [CH3C5H9] = 0.222 M B) [PCl5] = 1.80 M. A) [C6H12] = 0.037 atm.125 atm B) P(cis-2-butene) = 0.45 M D) 0.100 M. find the equilibrium concentrations of C6H12 and CH3C5H9 if the initial concentrations are 0. [PCl3] = 0.250 atm D) P(cis-2-butene) = 0.80.250 atm of cis-2-butene and 0.0280 M.085 atm.28 M C) 0.200 M and 0. equals 0.062 M B) [C6H12] = 0. Kp. Kc.038 M D) [C6H12] = 0.5 Using the Equilibrium Constant 57) Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the reaction: PCl5(g) ⇌ PCl3(g) + Cl2(g) At 250°C. [Cl2] = 1.0625 and [CH3C5H9] = 0. 00 × 10-4 C) 1.4228 D) 1.07428 B) 0.3 C) 4.43 B) 2.5 Using the Equilibrium Constant 61) Ammonium carbamate can dissociate into gases at 25°C according to the reaction: NH2COONH4(s) ⇌ 2 NH3(g) + CO2(g) If sufficient ammonium carbamate is sealed in a flask. 0. What is the value of Kp at 25°C? A) 2. What is the value of Kp at that temperature? A) 0.00 mol of acid in a 1.70 at 731 K for the reaction: H2(g) + I2(g) ⇌ 2 HI(g).08592 atm each of H2 and I2 and 1. What is the value of the equilibrium constant.0000 atm of HI.6 D) 5.5 Using the Equilibrium Constant 60) When baking soda is heated it decomposes according to the following reaction: 2 NaHCO3(s) ⇌ Na2CO3(s) + H2O(g) + CO2(g) If sufficient baking soda is placed in a container and heated to 90°C.7955 atm B) 0.4 Answer: D Topic: Section 13.00 L flask. the total pressure of the gases is 0.58) The esterification of acetic acid and ethanol is given by the reaction below: C2H5OH(aq) + CH3COOH(aq) ⇌ CH3COOC2H5(aq) + H2O(l) When 1.00 mol of ethanol was mixed with 2.5 Using the Equilibrium Constant 59) Kp is equal to 48.9108 atm C) 0.9140 atm D) 0.5 Using the Equilibrium Constant 16 Copyright © 2012 Pearson Education.42 × 10-1 Answer: A Topic: Section 13.60 × 10-3 D) 3.9498 atm Answer: B Topic: Section 13. . Inc.117 atm at equilibrium. Kc? A) 0.86 mol of ester was formed at room temperature.5451 atm.091 Answer: A Topic: Section 13. the total pressure will be 0. What is the pressure of HI at equilibrium? A) 0. Initially the mixture contains 0.2973 C) 0.37 × 10-4 B) 2. A) 4.40 × 10-2 C) 3.9 × 10-2 and Kc2 = 6.2 × 102 Answer: A Topic: Section 13.00 × 1014 D) 2. What is the value of Kc at that temperature if the flask contains 0. K3. Inc. and K2 = 1.104 mol of H2 at equilibrium? A) 7. the result is reaction (3). find the equilibrium constant. At a certain temperature a 2.00 × 1014.00 × 10-2 D) 2.50 × 1010 C) 1.04 × 10-2 B) 4.600 mol of HBr.9 × 10-2 D) 9.5 Using the Equilibrium Constant 64) Oxalic acid can donate two protons to water in successive reactions: (1) H2C2O4(aq) + H2O(l) ⇌ H3O+(aq) + HC2O4-(aq) (2) HC2O4-(aq) + H2O(l) ⇌ H3O+(aq) + C2O42-(aq) If Kc1 = 5. . what is the value of Kc for reaction (3)? (3) H2C2O4(aq) + 2 H2O(l) ⇌ 2 H3O+(aq) + C2O42-(aq) A) 3.4 × 10-5 at 25°C.22 × 1017 Answer: B Topic: Section 13.1 × 10-3 C) 5.10 × 10-1 Answer: A Topic: Section 13.8 × 10-6 B) 1.5 Using the Equilibrium Constant 17 Copyright © 2012 Pearson Education.00 L flask is initially filled only with 0.50 × 10-18 B) 4.5 Using the Equilibrium Constant 63) When reaction (1) and (2) below are added together.50 × 10-4. 1) H2O(l) + HNO2(aq) ⇌ H3O+(aq) + NO2-(aq) 2) H3O+(aq) + OH-(aq) ⇌ 2 H2O(l) 3) HNO2(aq) + OH-(aq) ⇌ NO2-(aq) + H2O(l) If K1 = 4.62) Gaseous hydrogen bromide decomposes at elevated temperatures according to the following equation: 2 HBr(g) ⇌ H2(g) + Br2(g). 65) Acids donate protons to water according to the general equation: HA(aq) + H2O(l) ⇌ H3O+(aq) + A-(aq) Consider the following acids and their equilibrium constants for reaction with water at 25°C.] C) Kc = 3 = 4. Kc = 3.5 × 10–4 [HF] + B) Kc = [H3O ][OCl ] = 3. Kc = 4.9 × 10-4 M Answer: C Topic: Section 13.0 × 10-9 B) HNO2.e.5 × 10–2 M C) 1.5 × 10-4.0 M? A) 1.5 Using the Equilibrium Constant 66) For acid solutions of the same molarity acid strength is proportional to the equilibrium concentration of H3O+. Inc. . which is the strongest acid (i. For equimolar solutions of acids. which donates the most protons to water)? A) HBrO. What is the equilibrium concentration of H3O+ if the initial concentration of HF is 1. Kc = 2. Kc = 1. If all the acids have the same initial concentration.5 × 10-4 D) HIO3.5 Using the Equilibrium Constant 67) The equilibrium constant Kc for the reaction HF(aq) + H2O(l) ⇌ H3O+(aq) +F-(aq) is 3. which equilibrium expression below corresponds to the strongest acid? + A) Kc = [H3O ][F ] = 3.5 × 10–4 [HNO2 ] + D) Kc = [H3O ][CN ] = 4.5 Using the Equilibrium Constant 18 Copyright © 2012 Pearson Education.0 M B) 3.5 × 10-4 C) HF.9 × 10–2 M D) 1.5 × 10–8 [HOCl] [H O+ ][NO2.9 × 10–10 [HCN] Answer: C Topic: Section 13.7 × 10-1 Answer: D Topic: Section 13. 5 Using the Equilibrium Constant 70) "If a stress is applied to a reaction mixture at equilibrium. the reaction occurs in the direction that will relieve the stress.6 Factors That Alter the Composition of an Equilibrium Mixture: Le Chatelier's Principle 19 Copyright © 2012 Pearson Education. C) the Law of Mass Action.8 × 10-6 B) CaCO3. B) the Law of Combining Volumes. Answer: D Topic: Section 13. . Given the following salts and their equilibrium constants for the reaction above at 25°C. Kc = 2. Kc = 1.2 × 10-5 C) CaCO3. D) Le Châtelier's principle. Kc = 5.68) The solubility of 1:1 salts is measured by the equilibrium constant for the general reaction: MX(s) = Mn+(aq) + Xn-(aq).0 × 10-9 C) SrCO3.6 × 10-10 D) BaCO3.6 × 10-9 Answer: C Topic: Section 13. Answer: D Topic: Section 13. Kc = 1. Kc = 2. Kc = 5." This statement is called A) the First Law of Thermodynamics. Kc = 1. Inc.6 × 10-9 D) CaF2. Kc = 6. Given the following salts and their equilibrium constants for the reaction above at 25°C.5 Using the Equilibrium Constant 69) Salt solubilities can be compared by the concentration of cation formed when the salt dissolves in the general reaction: MaXb(s) ⇌ a Mb+(aq) + b Xa-(aq).8 × 10-10 B) Ag2SO4.5 × 10–10 Answer: A Topic: Section 13.6 Factors That Alter the Composition of an Equilibrium Mixture: Le Chatelier's Principle 71) Which of the following changes in reaction conditions will alter the composition of an equilibrium mixture of gases for a reaction having unequal moles of gaseous products and gaseous reactants? A) addition of reactants or products B) decreasing the pressure or volume C) increasing the temperature D) All of these will alter the equilibrium concentrations. which salt is the least soluble? A) MgCO3. which salt is the least soluble? A) AgCl. Inc.increases.decreases. which change in conditions made to the system at equilibrium will result in a net reaction to the right to form more product? C(s) + 2 H2(g) ⇌ CH4(g) ΔH° = –74. D) No color change is observed. which of the following changes in reaction conditions will not alter the equilibrium concentrations? A) addition of an inert gas to the reaction mixture B) addition of reactants or products C) decreasing the pressure or volume D) increasing the temperature Answer: A Topic: Section 13. what happens to the solution? If the concentration of [Co(H2O)6] A) The concentration of [CoCl4]2.7 Altering an Equilibrium Mixture: Changes in Concentration 20 Copyright © 2012 Pearson Education. Answer: A Topic: Section 13.6 Factors That Alter the Composition of an Equilibrium Mixture: Le Chatelier's Principle 73) For the reaction shown below.8 kJ A) adding more C B) decreasing the concentration of H2 C) increasing the concentration of H2 D) increasing the concentration of CH4 Answer: C Topic: Section 13.7 Altering an Equilibrium Mixture: Changes in Concentration 75) Iron oxide ores are reduced to iron metal by exothermic reaction with carbon monoxide: FeO(s) + CO(g) ⇌ Fe(s) + CO2(g) Which of the following changes in condition will cause the equilibrium to shift to the right? A) add FeO B) add CO C) add CO2 D) raise the temperature Answer: B Topic: Section 13.(aq) ⇌ [CoCl4]2. B) The concentration of [CoCl4]2.72) For a homogeneous equilibrium of gases.(aq) + 6 H2O (l) (pink) (blue) 2+ is increased.7 Altering an Equilibrium Mixture: Changes in Concentration 74) The pink and blue species below form a violet colored mixture at equilibrium: [Co(H2O)6]2+ (aq) + 4 Cl. . C) The solution becomes colorless. which change in conditions made to the system at equilibrium will result in a net reaction to the right to form more product? C(s) + 2 H2(g) ⇌ CH4(g) ΔH° = – 74. If the reaction takes place in a closed container.8 Altering an Equilibrium Mixture: Changes in Pressure and Volume 21 Copyright © 2012 Pearson Education. .8 kJ A) adding He B) adding more C C) decreasing the volume D) increasing the volume Answer: C Topic: Section 13.7 Altering an Equilibrium Mixture: Changes in Concentration 77) A crude type of disappearing ink is based on the following endothermic equilibrium: [Co(H2O)6]Cl2 (aq) ⇌ [CoCl2(H2O)4] (aq) + 2 H2O (l) (colorless) (blue) If the reactant solution is used to write on a piece of paper and the paper is allowed to partially dry.8 Altering an Equilibrium Mixture: Changes in Pressure and Volume 79) Which change in the system will drive equilibrium to the left in the reaction below? N2O5(g) ⇌ NO2(g) + NO3(g) A) decrease the amount of NO3 B) increase the amount of N2O5 C) increase the pressure D) increase the volume Answer: C Topic: Section 13. Inc. what can be done to bring out the colored handwriting? A) add water B) decrease the volume C) put the paper in a freezer D) put the paper in an oven Answer: D Topic: Section 13.7 Altering an Equilibrium Mixture: Changes in Concentration 78) For the reaction shown below. which one of the following reaction conditions will not decrease the concentration of water vapor? 2 NaHCO3(s) ⇌ Na2CO3(s) + CO2(g) + H2O(g) A) add CO2 B) cool the container C) decrease the volume of the container D) remove some NaHCO3 Answer: D Topic: Section 13.76) The enthalpy for the following reaction is 136 kJ. depending on whether the reaction is exothermic or endothermic.9 Altering an Equilibrium Mixture: Changes in Temperature 83) The overall reaction for photosynthesis can be represented by the following equation: 6 CO2(g) + 6 H2O(l) ⇌ C6H12O6(s) + 6 O2(g) The enthalpy change for this reaction is 2802 kJ. Inc. . C) The value of Kp always increases with an increase in temperature. which change in reaction conditions below will cause the equilibrium to shift to the right? A) add more NH3 B) add more NH4Br C) decrease the temperature D) double the volume of the container Answer: D Topic: Section 13.80) Ammonium bromide is a crystalline solid that decomposes endothermically when heated: NH4Br(s) ⇌ NH3(g) + HBr(g). Answer: D Topic: Section 13. When solid NH4Br is added to an evacuated flask at 300°C.9 Altering an Equilibrium Mixture: Changes in Temperature 82) What effect will a change in temperature have on the value of Kp? A) It will have no effect on the value of Kp. B) The value of Kp always decreases with an increase in temperature.8 kJ A) adding more C B) increasing the volume C) lowering the temperature D) raising the temperature Answer: C Topic: Section 13.8 Altering an Equilibrium Mixture: Changes in Pressure and Volume 81) For the reaction shown below. Which of the following changes in condition will shift the equilibrium to the right? A) increase the pressure of O2 B) increase the temperature C) remove CO2 by reaction with CaO(s) D) remove one-half of C6H12O6(s) Answer: B Topic: Section 13.9 Altering an Equilibrium Mixture: Changes in Temperature 22 Copyright © 2012 Pearson Education. which change in conditions made to the system at equilibrium will result in a net reaction to the right to form more product? C(s) + 2 H2(g) ⇌ CH4(g) ΔH° = –74. D) The value of Kp will decrease or increase with an increase in temperature. 10 The Effect of a Catalyst on Equilibrium 23 Copyright © 2012 Pearson Education. D) The Ca(OH)2(s) completely dissolves.ion B) add an anion with which Ca2+ is even less soluble than calcium carbonate C) increase the temperature D) All of these will shift reaction to the right.84) The dissolution of calcium hydroxide is exothermic. . Inc.9 Altering an Equilibrium Mixture: Changes in Temperature 86) The decomposition of nitrosyl bromide is exothermic: 2 NOBr(g) ⇌ 2 NO(g) + Br2(g). B) The amount of Ca(OH)2(s) increases. Answer: D Topic: Section 13. Which of the following changes in reaction condition will shift the reaction to the left? A) add more NOBr B) decrease the temperature C) increase the container volume D) None of these Answer: D Topic: Section 13. Ca(OH)2(s) ⇌ Ca2+(aq) + 2 OH-(aq) What happens when the solution of Ca(OH)2 is heated? A) The amount of Ca(OH)2(s) decreases.9 Altering an Equilibrium Mixture: Changes in Temperature 87) Which will not alter the composition of an equilibrium mixture? A) addition of a catalyst B) addition of heat C) addition of more product D) addition of more reactant Answer: A Topic: Section 13. Which change in reaction condition below will shift the equilibrium to the right? A) add an acid to react with CO32.9 Altering an Equilibrium Mixture: Changes in Temperature 85) Calcium carbonate is relatively insoluble and the dissolution reaction is endothermic: CaCO3(s) ⇌ Ca2+(aq) + CO32-(aq). C) The amount of Ca(OH)2(s) remains unchanged.10 The Effect of a Catalyst on Equilibrium 88) Which of the following changes in reaction conditions will not alter the composition of a homogeneous equilibrium mixture of gases in a reaction having unequal moles of gaseous products and reactants? A) addition of a catalyst B) addition of reactants or products C) decreasing the temperature D) increasing the pressure or volume Answer: A Topic: Section 13. Answer: B Topic: Section 13. B) A catalyst increases the temperature of a reaction.7 × 10-12 C) 1. B) kfwd equals krev. C) opposing reactions cease and the system is static. Answer: D Topic: Section 13.10 The Effect of a Catalyst on Equilibrium 91) A catalyst increases the rate of a chemical reaction by providing a lower-energy mechanism for the reaction. C) A catalyst is consumed in a chemical reaction.11 The Link Between Chemical Equilibrium and Chemical Kinetics 93) Find the equilibrium constant for the reaction: A(g) + B(g) ⇌ 2C(g) at 25°C when k equals 1.7 × 10-13 M-1s-1 for the reaction: 2 C(g) ⇌ A(g) + B(g) at 25°C. Inc. for A) both the forward reaction and the reverse reaction. Answer: D Topic: Section 13. A) 3. Ea.10 The Effect of a Catalyst on Equilibrium 92) A reaction reaches dynamic equilibrium at a given temperature when A) the amount of products exceeds the amount of reactants. Answer: A Topic: Section 13.1 × 10-12 D) 5. B) neither the forward reaction nor the reverse reaction.10 The Effect of a Catalyst on Equilibrium 90) A catalyst increases the overall rate of reaction by lowering the activation energy. D) only the reverse reaction.89) Which of the following statements about a catalyst is true? A) A catalyst changes the position of the equilibrium in a reaction. which one of the following is not affected? A) activation energy for the forward reaction B) activation energy for the reverse reaction C) equilibrium constant D) rate of the reverse reaction Answer: C Topic: Section 13.4 × 1012 M-1s-1 for the reaction A(g) + B(g) ⇌ 2C(g) at 25°C and k equals 2. D) the relative amounts of reactants and products are constant and ratefwd = raterev. C) only the forward reaction. When this occurs.11 The Link Between Chemical Equilibrium and Chemical Kinetics 24 Copyright © 2012 Pearson Education.2 Answer: D Topic: Section 13. . D) A catalyst provides a lower energy pathway for a reaction.8 × 10-25 B) 1. 18. Which statement is true? A) The activation energy decreases with increasing temperature. Answer: D Topic: Section 13. Kp = 4. solutions of hexaammine cobalt(III) can be stored in acidic solution for months without noticeable decomposition. D) Unstable species react rapidly. Inc.18 × 10-3 s-1 C) 2. C) Keq < 103 and Ea is very large. C) The reaction is endothermic.11 The Link Between Chemical Equilibrium and Chemical Kinetics 96) The hexaammine cobalt(III) ion is very unstable in acidic aqueous solution: [Co(NH3)6]3+(aq) + 6 H3O+(aq) → [Co(H2O)6]4+(aq) + 6 NH4+(aq) However. C) Stable species do not react rapidly.54 × 103 and at 1125 K. B) Stable species can react rapidly. Which statement below about the equilibrium constant and the activation energy for the reaction is true? A) Keq < 103 and Ea is very small. a certain first order reaction has a rate constant equal to 1. incorporation of 14C labelled cyanide ion (14CN-) is very rapid: [Ni(CN)4]2-(aq) + 4 14CN-(aq) = [Ni(14CN)4]2-(aq) + 4 CN-(aq) Which statement below is correct with regard to stability and rate of reaction? A) Equilibrium is static. B) Keq > 103 and Ea is very small. Kp = 1.18 × 103 s-1 Answer: A Topic: Section 13. D) The reaction is exothermic.11 The Link Between Chemical Equilibrium and Chemical Kinetics 95) Nickel metal can be prepared by the reduction of nickel oxide: NiO(s) + CO(g) ⇌ CO2(g) + Ni(s) At 936 K.11 The Link Between Chemical Equilibrium and Chemical Kinetics 97) The reaction below virtually goes to completion because cyanide ion forms very stable complexes with Ni2+ ion: [Ni(H2O)6]2+(aq) + 4 CN-(aq) → [Ni(CN)4]2-(aq) + 6 H2O(l) At the same time. D) Keq > 103 and Ea is very large. Answer: B Topic: Section 13. B) The activation energy increases with increasing temperature.39 × 10-4 s-1 B) 4.58 × 103. Answer: D Topic: Section 13. .11 The Link Between Chemical Equilibrium and Chemical Kinetics 25 Copyright © 2012 Pearson Education.00 × 10-3 s-1 and an equilibrium constant.94) At 25°C. equal to 4.39 × 102 s-1 D) 4. What is the rate constant for the reverse reaction? A) 2. Kc. Inc. Each of the following series of pictures represents a separate experiment in which time increases from left to right.Consider the interconversion of A molecules (shaded spheres) and B molecules (unshaded spheres) according to the reaction A ⇌ B. 98) Which of these experiments has resulted in an equilibrium state? A) all of the experiments except experiment (1) B) all of the experiments except experiment (2) C) all of the experiments except experiment (3) D) all of the experiments except experiment (4) Answer: B Topic: Conceptual Problems 99) What is the value of the equilibrium constant Kc for the reaction A ⇌ B? A) Kc = 0.0 C) Kc = 12 D) Kc = 27 Answer: B Topic: Conceptual Problems 26 Copyright © 2012 Pearson Education.33 B) Kc = 3. . The following pictures represent reaction mixtures that contain A2 molecules (shaded) and B2 molecules (unshaded). X atoms are shaded. C. Which reaction mixture is at equilibrium? A) reaction mixture (1) B) reaction mixture (2) C) reaction mixture (3) D) reaction mixture (4) Answer: B Topic: Conceptual Problems 27 Copyright © 2012 Pearson Education. and AB molecules. 100) Which reaction has the largest equilibrium constant? A) A2 + B2 ⇌ 2 AB B) A2 + C2 ⇌ 2 AC C) A2 + D2 ⇌ 2 AD D) A2 + E2 ⇌2 AE Answer: A Topic: Conceptual Problems 101) Which reaction has the smallest equilibrium constant? A) A2 + B2 ⇌ 2 AB B) A2 + C2 ⇌ 2 AC C) A2 + D2 ⇌ 2 AD D) A2 + E2 ⇌ 2 AE Answer: C Topic: Conceptual Problems 102) The reaction A2 + B2 ⇌ 2 AB has an equilibrium constant Kc = 1.The following pictures represent the equilibrium state for four different reactions of the type A2 + X2 ⇌ 2 AX (X = B. .8. Inc. A atoms are unshaded. D. E). which interconvert according to the equation cis-C2H2X2 ⇌ trans-C2H2X2. which of the other mixtures are also at equilibrium? A) mixture (2) B) mixture (3) C) mixture (4) D) None of the other mixtures are at equilibrium.103) The following pictures represent mixtures of cis-C2H2X2 molecules and trans-C2H2X2 molecules. . If mixture (1) is at equilibrium. which of the other mixtures are also at equilibrium? A) mixture (2) B) mixture (3) C) mixture (4) D) None of the other mixtures are at equilibrium. which interconvert according to the equation cis-C2H2X2 ⇌ trans-C2H2X2. Answer: D Topic: Conceptual Problems 28 Copyright © 2012 Pearson Education. If mixture (1) is at equilibrium. Inc. Answer: B Topic: Conceptual Problems 104) The following pictures represent mixtures of cis-C2H2X2 molecules and trans-C2H2X2 molecules. which interconvert according to the equation A2B4 ⇌ 2 AB2. If mixture (1) is at equilibrium. If mixture (1) is at equilibrium. . Answer: A Topic: Conceptual Problems 106) The following pictures represent mixtures of A2B4 molecules and AB2 molecules. which of the other mixtures are also at equilibrium? A) mixture (2) B) mixture (3) C) mixture (4) D) None of the other mixtures are at equilibrium. Inc. which interconvert according to the equation A2B4 ⇌ 2 AB2.105) The following pictures represent mixtures of A2B4 molecules and AB2 molecules. Answer: C Topic: Conceptual Problems 29 Copyright © 2012 Pearson Education. which of the other mixtures are also at equilibrium? A) mixture (2) B) mixture (3) C) mixture (4) D) None of the other mixtures are at equilibrium. For this reaction the value of the equilibrium constant is A) Kc < 1. time plot for the reaction A ⇌ B.107) Shown below is a concentration vs. D) Kc > 1. B) Kc = 0. C) Kc = 1. D) Kc > 1. Answer: A Topic: Conceptual Problems 30 Copyright © 2012 Pearson Education. Inc. . B) Kc = 0. For this reaction the value of the equilibrium constant is A) Kc < 1. Answer: D Topic: Conceptual Problems 108) Shown below is a concentration vs. time plot for the reaction A ⇌ 2B. C) Kc = 1. For this reaction the value of the equilibrium constant is A) Kc < 1. . time plot for the reaction A ⇌ B. B) Kc = 0. time plot for the reaction A ⇌ 2B. Answer: C Topic: Conceptual Problems 110) Shown below is a concentration vs. C) Kc = 1. B) Kc = 0.109) Shown below is a concentration vs. D) Kc > 1. For this reaction the value of the equilibrium constant is A) Kc < 1. D) Kc > 1. Inc. Answer: A Topic: Conceptual Problems 31 Copyright © 2012 Pearson Education. C) Kc = 1. time plot for the reaction A ⇌ 2B. Answer: A Topic: Conceptual Problems 112) Shown below is a concentration vs. B) Kc = 0. C) Kc = 1. C) Kc = 1. D) Kc > 1. Answer: A Topic: Conceptual Problems 32 Copyright © 2012 Pearson Education.111) Shown below is a concentration vs. D) Kc > 1. Inc. B) Kc = 0. . time plot for the reaction A ⇌ B. For this reaction the value of the equilibrium constant is A) Kc < 1. For this reaction the value of the equilibrium constant is A) Kc < 1. kf. kf. What is the relationship between the rate constant for the forward reaction. What is the relationship between the rate constant for the forward reaction.113) The following picture represents the equilibrium state for the reaction A2 + B2 ⇌ 2AB. and the rate constant for the reverse reaction kr? A) kf < kr B) kf = kr = 0 C) kf = kr D) kf > kr Answer: C Topic: Conceptual Problems 114) The following picture represents the equilibrium state for the reaction A2 + B2 ⇌ 2AB. . Inc. and the rate constant for the reverse reaction kr? A) kf < kr B) kf = kr = 0 C) kf = kr D) kf > kr Answer: D Topic: Conceptual Problems 33 Copyright © 2012 Pearson Education. 8. and the rate constant for the reverse reaction kr? A) kf < kr B) kf = kr = 0 C) kf = kr D) kf > kr Answer: A Topic: Conceptual Problems The reaction A2 + B2 ⇌ 2AB has an equilibrium constant Kc = 1. The following pictures represent reaction mixtures that contain A2 molecules (shaded) and B2 molecules (unshaded).115) The following picture represents the equilibrium state for the reaction A2 + B2 ⇌ 2AB. 116) Which nonequilibrium mixture will react in the forward direction to reach equilibrium? A) reaction mixture (1) B) reaction mixture (2) C) reaction mixture (3) D) reaction mixture (4) Answer: C Topic: Conceptual Problems 117) Which nonequilibrium mixtures will react in the reverse direction to reach equilibrium? A) reaction mixtures (1) and (2) B) reaction mixtures (1) and (4) C) reaction mixtures (2) and (3) D) reaction mixtures (3) and (4) Answer: B Topic: Conceptual Problems 34 Copyright © 2012 Pearson Education. . kf. and AB molecules. What is the relationship between the rate constant for the forward reaction. Inc. the number of B atoms will decrease. what will happen to the number of AB molecules and the number of B atoms? A) The number of AB molecules and the number of B atoms will both decrease. B) The number of AB molecules will increase. Answer: B Topic: Conceptual Problems 35 Copyright © 2012 Pearson Education. Inc.The following pictures represent the initial state and the equilibrium state for the gaseous state reaction of A2 molecules (shaded spheres) with B atoms (unshaded spheres) to give AB molecules. C) The number of AB molecules will decrease. the number of B atoms will increase. D) The number of AB molecules and the number of B atoms will both increase. 118) What is the best balanced chemical equation for the reaction? A) A2 + B ⇌ A2B B) A2 + 2 B ⇌ A2B2 C) A2 + 2 B ⇌ 2 AB D) 6 A2 + 9 B ⇌ 3 A2 + 3B + 6 AB Answer: C Topic: Conceptual Problems 119) If the volume of the equilibrium mixture is decreased. . Consider the reaction A + B ⇌ 2 AB. what will be observed? A) The reaction will go in the forward direction decreasing the number of A atoms and B atoms and increasing the number of AB molecules. Answer: D Topic: Conceptual Problems Picture (1) represents the equilibrium mixture for the reaction A + B ⇌ 2 AB at 298 K. B) The reaction will go in the forward direction increasing the number of A atoms and B atoms and decreasing the number of AB molecules. which picture (2)-(4) represents the equilibrium mixture at 400 K? A) picture (2) B) picture (3) C) picture (4) D) None of these Answer: B Topic: Conceptual Problems 36 Copyright © 2012 Pearson Education. which picture (2)-(4) represents the equilibrium mixture at 400 K? A) picture (2) B) picture (3) C) picture (4) D) None of these Answer: C Topic: Conceptual Problems 122) If this reaction is endothermic. B atoms (unshaded spheres). Inc. 121) If this reaction is exothermic. C) The reaction will go in the reverse direction decreasing the number of A atoms and B atoms and increasing the number of AB molecules. 120) If the barrier between the two vessels is removed and the contents of the two vessels are allowed to mix. The vessel on the right contains an equilibrium mixture of A atoms (shaded spheres). . and AB molecules. D) The reaction will go in the reverse direction increasing the number of A atoms and B atoms and decreasing the number of AB molecules. which picture (2)-(4) represents the equilibrium at the reduced volume? A) picture (2) B) picture (3) C) picture (4) D) None of these Answer: A Topic: Conceptual Problems Picture (1) represents an equilibrium mixture of solid CaCO3. solid CaO. 124) Which picture (2)-(4) represents the equilibrium mixture after addition of four more CO2 molecules? A) picture (2) B) picture (3) C) picture (4) D) None of these Answer: A Topic: Conceptual Problems 125) Which picture (2)-(4) represents the equilibrium mixture at a higher temperature? A) picture (2) B) picture (3) C) picture (4) D) None of these Answer: C Topic: Conceptual Problems 37 Copyright © 2012 Pearson Education.123) Picture (1) represents the equilibrium mixture for the gas-phase reaction A + B ⇌ 2 AB at 298 K. and gaseous CO2. . If the volume of the equilibrium mixture is decreased. Inc. obtained as a result of the endothermic decomposition of CaCO3. 11 M B) 1.3 × 10.126) Which picture (2)-(4) represents the equilibrium mixture when a catalyst is added? A) picture (2) B) picture (3) C) picture (4) D) All of these Answer: A Topic: Conceptual Problems 127) Which picture (2)-(4) represents the equilibrium mixture when more solid CaCO3 is added? A) picture (2) B) picture (3) C) picture (4) D) All of these Answer: A Topic: Conceptual Problems 128) Which picture (2)-(4) represents the equilibrium mixture when more solid CaO is added? A) picture (2) B) picture (3) C) picture (4) D) All of these Answer: A Topic: Conceptual Problems 13.3 × 10-10 at 25°C.2 × 10. What is the concentration of N2 gas at equilibrium when the concentration of NO2 is five times the concentration of O2 gas? A) 3.7 × 10-10 M C) 6. Inc. If Kp is 1.0 × 109 M D) 3.7 atm B) 4.7 × 10.1 × 103 atm D) 4.4 atm C) 2.2 Algorithmic Questions 1) For the reaction: N2(g) + 2 O2(g) ⇌ 2 NO2(g).5 × 103 at 400°C. what is the partial pressure of ammonia at equilibrium when N2 is 0. Kc = 8.3 The Equilibrium Constant Kp 38 Copyright © 2012 Pearson Education. . 10 atm and H2 is 0.4 × 106 atm Answer: B Topic: Section 13.0 × 1010 M Answer: D Topic: Section 13.2 The Equilibrium Constant Kc 2) The decomposition of ammonia is: 2 NH3(g) = N2(g) + 3 H2(g).15 atm? A) 2. 45 M. the concentration of NH3 increases.5 Using the Equilibrium Constant 6) At a certain temperature. D) not at equilibrium and will shift to the right to achieve an equilibrium state. predict the direction in which the system will shift if the initial concentrations of C6H12 and MCP are 0. respectively. the system is A) at equilibrium.143 at 25°C for this reaction.5 Using the Equilibrium Constant 4) The equilibrium constant. D) is not at equilibrium and will remain in an unequilibrated state. H2. and NH3 are mixed. 0400 M and 0. [O2] = 0.00 M. 0200 M. The system A) will shift left. Kp. Which statement below is true? A) Kc < Q B) Kc > Q C) Kc = Q D) More information is needed to make a statement about Kc. Answer: B Topic: Section 13. B) will shift right. B) not at equilibrium and will remain in an unequilibrated state.00 atm of each gas. nitrogen and hydrogen react to form ammonia: N2(g) + 3 H2(g) ⇌ 2 NH3(g). C) The system is already at equilibrium. If a flask initially contains 5.3) The equilibrium constant is equal to 5. Inc. B) It will shift right.00 at 1300 K for the reaction: 2 SO2(g) + O2(g) ⇌ 2 SO3(g). If initial concentrations are [SO2] = 6.00 M. C) not at equilibrium and will shift to the left to achieve an equilibrium state. When initial amounts of N2. and [SO3] = 9. equals 3. Answer: A Topic: Section 13. Answer: B Topic: Section 13. C) is already at equilibrium. Answer: A Topic: Section 13.5 Using the Equilibrium Constant 5) Cyclohexane (C6H12) undergoes a molecular rearrangement in the presence of AlCl3 to form methylcyclopentane (MCP) according to the equation: C6H12 ⇌ MCP If Kc = 0. . D) The system is not at equilibrium and will remain in an unequilibrated state.5 Using the Equilibrium Constant 39 Copyright © 2012 Pearson Education.40 at 25°C for the isomerization reaction: cis-2-butene ⇌ trans-2-butene. in what direction will the system shift to reach equilibrium? A) It will shift left. [CH3C5H9] = 0.0010 M CO2 and 0.0114 mol Answer: B Topic: Section 13. What is the equilibrium concentration of CO? A) 7. 253 M. [CH3C5H9] = 0.4 × 102 for the reaction: 2 CO(g) + O2(g) ⇌ 2 CO2(g).400 mol of CO2 and 0. how many moles of CO are also present in the flask? A) 0. C6H12.80 atm Answer: A Topic: Section 13.143 at 25°C for this reaction. At this temperature. respectively. atm C) P(butane) = 19. 159 M.100 mol of O2 at equilibrium. 041 M. undergoes a molecular rearrangement in the presence of AlCl3 to form methylcyclopentane.00-L flask contains 0.0 atm.80 atm and P(isobutane) = 20.4 × 10-2 M D) 1. 241 M. 075 M.7) An equilibrium mixture of CO.4 M C) 1. [CH3C5H9] = 0. 185 mol C) 0.2 atm B) P(butane) = 0. CH3C5H9. [CH3C5H9] = 0.5 Using the Equilibrium Constant 10) Cyclohexane.77 atm D) P(butane) = 20 atm and P(isobutane) = 0.5 Using the Equilibrium Constant 40 Copyright © 2012 Pearson Education. respectively. A) [C6H12] = 0.4 × 10.1 × 10. .107 mol D) 0. 034 M D) [C6H12] = 0. 022 M Answer: C Topic: Section 13. 116 M C) [C6H12] = 0. atm and 0. Kc equals 1. find the equilibrium concentrations of C6H12 and CH3C5H9 if the initial concentrations are 0.2 × 10-1 M Answer: B Topic: Section 13.2 atm and P(isobutane) = 0. If the initial pressures of butane and isobutane are 20. what are the pressures of the two gases at equilibrium? A) P(butane) = 0. Inc.5 Using the Equilibrium Constant 9) For the isomerization reaction: butane ⇌ isobutane Kp equals 25 at 500°C.555 mol B) 0.5 Using the Equilibrium Constant 8) At a certain temperature. If a 3. Kc equals 1. 0100 M O2.77 atm and P(isobutane) = 19.7 M B) 8.4 × 102 for the reaction: 2 CO(g) + O2(g) ⇌ 2 CO2(g). according to the equation: C6H12 ⇌ CH3C5H9 If Kc = 0. O2 and CO2 at a certain temperature contains 0.200 M and 0. 041 M B) [C6H12] = 0. 0200 M Fe3+ is initially mixed with 1.250 atm of cis-2-butene and 0.0-L flask? A) 0.83 M. and [Cl2] = 0.5 Using the Equilibrium Constant 14) Kc is 1.83 M Answer: A Topic: Section 13.0 426 atm and P(trans-2-butene) = 0.250 atm D) P(cis-2-butene) = 0.0100 M C) 8. 335 M C) [PCl5] = 1.11 for the reaction: 2 ICl(g) ⇌ I2(g) + Cl2(g). 45 M D) 0. 305 atm Answer: D Topic: Section 13. [PCl3] = 3. 145 atm B) P(cis-2-butene) = 0.96 M. 75 mol of Cl2 are initially mixed in a 2.11) At a certain temperature the equilibrium constant.00 M oxalate ion. What is the equilibrium concentration of ICl if 0.80 M.40 for the isomerization reaction: cis-2-butene ⇌ trans-2-butene. 22 M B) 0. [PCl3] = 1. 335 M. and [Cl2] = 3. [PCl3] = 0. equals 3. . If 0. what is the equilibrium pressure of each gas? A) P(cis-2-butene) = 0.44 × 10-22 M B) 0. If a flask initially contains 0. 160 atm C) P(cis-2-butene) = 0. 56 M Answer: C Topic: Section 13. 0625 M. Inc. 117 M B) [PCl5] = 0.94 × 1021 M Answer: A Topic: Section 13. 28 M C) 0.35 × 1019 M D) 6.5 Using the Equilibrium Constant 12) The equilibrium constant. 145 atm of trans-2-butene. what are the equilibrium concentrations of each gas? A) [PCl5] = 0. 117 M. and [Cl2] = 0. what is the concentration of Fe3+ ion at equilibrium? A) 1.67 × 1020 at 25°C for the formation of iron(III) oxalate complex ion: Fe3+(aq) + 3 C2O42-(aq) ⇌ [Fe(C2O4)3]3-(aq).0 735 atm and P(trans-2-butene) = 0.80 M.5 Using the Equilibrium Constant 41 Copyright © 2012 Pearson Education. If Kc = 1. Kc. 0898 atm and P(trans-2-butene) = 0. Kp.0 0765 M. 125 M PCl5 is added to the flask.80 M D) [PCl5] = 3.0 471 atm and P(trans-2-butene) = 0. 75 mol of I2 and 0.5 Using the Equilibrium Constant 13) Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the equation: PCl5(g) ⇌ PCl3(g) + Cl2(g) At 250° 0.80. [PCl3] = 0. equals 0. and [Cl2] = 1. 3 The Equilibrium Constant Kp 8) At 298 K. less than) 1.001 × 10-3.7 × 10-56 for the reaction 3 O2(g) ⇌ 2 O3(g). Kc. if the rate constant for the forward reaction is greater than the rate constant for the reverse reaction.13.3 The Equilibrium Constant Kp 42 Copyright © 2012 Pearson Education.64 × 10–3 Topic: Section 13. greater than.3 The Equilibrium Constant Kp 7) At 298 K. Answer: greater than Topic: Section 13.3 The Equilibrium Constant Kp 6) For the reaction shown below the value of Kp is ________ than the value of Kc. Answer: equilibrium Topic: Section 13. the value of Kc must be ________ (equal to.160 × 10-4 and [NO2]eq = 1.1 The Equilibrium State 3) For the reaction H2(g) + S(s) ⇌ H2S(g). the reaction is at ________.1 × 104 for the reaction CO(g) + 2 H2(g) ⇌ CH3OH(g). N2O4(g) ⇌ 2 NO2(g) Answer: 4. N2O4 and NO2 have equilibrium concentrations. when the rate of the forward reaction equals the rate of the reverse reaction.9 × 10-57 Topic: Section 13. for this reaction equals ________. Answer: PO2 Topic: Section 13. 1 Topic: Section 13. [N2O4]eq = 2. respectively. Kc = 1. Inc. What is the value of Kc at this temperature? Answer: 1.2 The Equilibrium Constant Kc 5) For the reaction CaCO3(s) ⇌ CaO(s) + O2(g) the equilibrium expression is Kp = ________. Kp = 2.2 The Equilibrium Constant Kc 4) For the reaction shown below. . What is the value of Kp at this temperature? Answer: 6. The equilibrium constant. because Δn = ________.3 Short Answer Questions 1) A reaction in which reactants form products in the forward reaction and products simultaneously form reactants in the reverse reaction is said to be ________.3 × 107 Topic: Section 13. N2O4(g) ⇌ 2 NO2(g) Answer: greater. Answer: reversible Topic: Section 13.1 The Equilibrium State 2) In a reversible reaction. 0 at 700 K for the reaction shown below. Inc. a net ________ (forward. H2(g) + I2(g) ⇌ 2 HI(g) If [H2(g)] = [I2(g)] = 0. Kp = 19. and Br2 are 1. HF(aq) + H2O(l) ⇌ H3O+(aq) + F–(aq) Answer: Topic: Section 13.7 × 10-7 Topic: Section 13. reverse) reaction must occur in order to achieve equilibrium.25 atm. Kp = 19. Kc Topic: Section 13.2 × 10-9 for the reaction 2 HBr(g) ⇌ H2(g) + Br2(g). and 2.45 atm.9 for the reaction Fe2O3(s) + 3 CO(g) ⇌ 2 Fe(s) + 3 CO2(g). 0.50 atm.3 The Equilibrium Constant Kp 10) At 1000 K. the molar concentration [HI((g)] = ________ at equilibrium.0 × 10-2 atm.9) At 1000 K. and Cl2 are 0. NO. Answer: right.9 for the reaction Fe2O3(s) + 3 CO(g) ⇌ 2 Fe(s) + 3 CO2(g). Answer: 1.2 × 10–22 M. and 0.0 × 10-4 atm. respectively. Kp = 0. left.5 Using the Equilibrium Constant 15) At an elevated temperature. Answer: forward Topic: Section 13.0503 Topic: Section 13. what is the equilibrium partial pressure of H2? Answer: 6.5 Using the Equilibrium Constant 43 Copyright © 2012 Pearson Education. .51 Topic: Section 13. Kp = 4. If the initial partial pressures of HBr. in order to achieve equilibrium a net reaction must occur from ________ to ________ until Qc = ________.27 × 10-4 Topic: Section 13.19 for the reaction 2 NOCl(g) ⇌ 2 NO(g) + Cl2(g).4 Heterogeneous Equilibria 12) Kc = 57. What is the value of Kp for the reaction 2 Fe(s) + 3 CO2(g) ⇌ Fe2O3(s) + 3 CO(g)? Answer: 0.3 The Equilibrium Constant Kp 11) For the reaction shown below the equilibrium constant expression for Kc = ________.5 Using the Equilibrium Constant 14) At an elevated temperature. 2. What is the value of Kp for the reaction 6 Fe(s) + 9 CO2(g) ⇌ 3 Fe2O3(s) + 9 CO(g)? Answer: 1.0 × 10-4 atm. respectively.200 M at equilibrium.2 × 10-42 at 500 K for the reaction shown below. If the initial partial pressures of NOCl.5 Using the Equilibrium Constant 13) Kc = 1. H2(g) ⇌ 2 H(g) If [H2] = 1 × 10-2 M and [H] = 1. H2. 7 Altering an Equilibrium Mixture: Changes in Concentration 20) According to Le Châtelier's principle. H Topic: Section 13. The reaction is not at equilibrium. Le Châtelier's principle predicts a net reaction from ________ to ________. The reaction is not at equilibrium. Fe3+(aq) + SCN-(aq) ⇌ FeSCN2+(aq) yellow colorless red Answer: left. Answer: forward Topic: Section 13. H2(g) ⇌ 2 H(g) Answer: H2. Inc. The effect of increasing the total volume of the system at equilibrium will ________ (decrease.5 Using the Equilibrium Constant 18) If additional SCN– is added to the equilibrium system shown below.7 Altering an Equilibrium Mixture: Changes in Concentration 19) The reaction CaCO3(s) ⇌ CaO(s) + O2(g) is endothermic 298 K. have no effect on) the total quantity of CaCO3 once equilibrium is reestablished. increase. causing the red color to become ________. Answer: decrease Topic: Section 13. there will be an increase in the concentration of ________ and a decrease in the concentration of ________. increase. reverse) direction in order to achieve equilibrium. right.8 Altering an Equilibrium Mixture: Changes in Pressure and Volume 21) The reaction CaCO3(s) ⇌ CaO(s) + O2(g) is endothermic 298 K. In order to attain equilibrium the reaction must proceed in the ________ (forward. if the volume of the vessel containing the equilibrium system shown below is decreased. . darker Topic: Section 13. reverse) direction in order to achieve equilibrium. the rate of the forward reaction is 0.25 M/s and the rate of the reverse reaction is 0. Answer: have no effect on Topic: Section 13. The effect of adding additional CaO to the system at equilibrium will ________ (decrease. In order to attain equilibrium the reaction must proceed in the ________ (forward.5 Using the Equilibrium Constant 17) For the reaction A2 + 2 B3 ⇌ 2 AB3. have no effect on) the total quantity of CaCO3 once equilibrium is reestablished.16) For the reaction 2 A + B2 ⇌ 2 AB. Answer: reverse Topic: Section 13. increase. the rate of the forward reaction is 0.8 Altering an Equilibrium Mixture: Changes in Pressure and Volume 22) The reaction CaCO3(s) ⇌ CaO(s) + O2(g) is endothermic 298 K.75 M/s.8 Altering an Equilibrium Mixture: Changes in Pressure and Volume 44 Copyright © 2012 Pearson Education. have no effect on) the total quantity of CaCO3 once equilibrium is reestablished. Answer: increase Topic: Section 13.25 M/s.75 M/s and the rate of the reverse reaction is 0. The effect of increasing the partial pressure of O2 in the system at equilibrium will ________ (decrease. have no effect on) the total quantity of CaCO3 once equilibrium is reestablished. increase. darker Topic: Section 13.9 Altering an Equilibrium Mixture: Changes in Temperature 25) The reaction CaCO3(s) ⇌ CaO(s) + O2(g) is endothermic 298 K. and the brown color will become ________.9 Altering an Equilibrium Mixture: Changes in Temperature 24) The reaction CaCO3(s) ⇌ CaO(s) + O2(g) is endothermic 298 K. . according to Le Châtelier's principle. The effect of increasing the temperature of the system at equilibrium will ________ (decrease. Inc. right.2 kJ colorless brown Answer: left.23) The reaction below is heated from 20°C to 90°C. there will be a net reaction from ________ to ________. Answer: have no effect on Topic: Section 13. N2O4(g) ⇌ 2 NO2(g) ΔH°= + 57. have no effect on) the total quantity of CaCO3 once equilibrium is reestablished. Answer: decrease Topic: Section 13. increase. The effect of adding a catalyst to the system at equilibrium will ________ (decrease.10 The Effect of a Catalyst on Equilibrium 45 Copyright © 2012 Pearson Education.