Chem 2 Chapter 14

107) Which statement is true for the following reaction at equilibrium at 25 C? H2(g) + Br2(g) ⇌ HBr(g); K= 1.9 × 1019 A) Concentration of HBr is high. B) Concentration of H2 and Br2 are high. C) The rate of the reaction is very slow. D) The reverse reaction does not happen.

A) Concentration of HBr is high.

106) Which statement is true for the following reaction at equilibrium at 25 C? N2(g) + O2(g) ⇌2NO(g); K= 4.1 × 10-31 A) Concentration of NO is high B) Concentration of N2 and O2 are high C) The rate of the reaction is very slow D) The reaction does not go in the forward direction

B) Concentration of N2 and O2 are high

90)At a certain temperature, nitrogen and hydrogen react to form ammonia: N2(g) + 3 H2(g) ⇌2 NH3(g) When initial amounts of N2, H2, and NH3 are mixed, the concentration of NH3 increases. 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.

B) Kc> Q

9) The equilibrium constant is given for one of the reactions below. Determine the value of the missing equilibrium constant. H2(g) + Br2(g) ⇌2 HBr(g) Kc= 3.8 × 10^4 2HBr(g) ⇌H2(g) + Br2(g) Kc= ? A) 1.9 × 10^4 B) 5.3 × 10^-5 C) 2.6 × 10^-5 D) 6.4 × 10^-4 E) 1.6 × 10^3

C) 2.6 × 10^-5 Note: Reverse the equation for K'=1/Kc which is 1/3.8x10^4 which is 2.6 × 10^-5

12) The equilibrium constant is given for one of the reactions below. Determine the value of the missing equilibrium constant. N2O4(g) ⇌2 NO2(g)Kc= 1.463 N2O4(g) ⇌6 NO2(g)Kc= ? A) 2.13 B) 0.685 C) 3.11 D) 1.46 E) 1.13

C) 3.11 Note: LOOK into this

14) The equilibrium constant is given for two of the reactions below. Determine the value of the missing equilibrium constant. A(g) + 2B(g) ⇌AB2(g) Kc = 59 AB2(g) + B(g) ⇌AB3(g) Kc= ? A(g) + 3B(g) ⇌AB3(g) Kc= 478 A) 3.5 × 10-5 B) 2.8 × 104 C) 8.1 D) 0.12 E) 89

C) 8.1 Note: KC2 = KC3 / KC1 = 478 / 59 = 8.107

40) Which of the following statements is true? A) If Q < K, it means the reverse reaction will proceed to form more reactants. B) If Q > K, it means the forward reaction will proceed to form more products. C) If Q = K, it means the reaction is at equilibrium. D) All of the above are true. E) None of the above are true.

C) If Q = K, it means the reaction is at equilibrium.

41) Consider the following reaction and its equilibrium constant: SO2(g) + NO2(g) ⇌SO3(g) + NO(g) Kc= 0.33A reaction mixture contains 0.39 M SO2, 0.14 M NO2, 0.11 M SO3 and 0.14 M NO. Which of the following statements is true concerning this system? A) The reaction will shift in the direction of reactants. B) The equilibrium constant will decrease. C) The reaction will shift in the direction of products. D) The reaction quotient will decrease. E) The system is at equilibrium.

C) The reaction will shift in the direction of products.

92) Cyclohexane, C6H12, undergoes a molecular rearrangement in the presence of AlCl3 to form methylcyclopentane, CH3C5H9, according to the equation: C6H12⇌CH3C5H9 If Kc= 0.143 at 25°C for this reaction, find the equilibrium concentrations of C6H12 and CH3C5H9 if the initial concentrations are 0.200 M and 0.075 M, respectively. A) [C6H12] = 0.041 M, [CH3C5H9] = 0.041 M B) [C6H12] = 0.159 M, [CH3C5H9] = 0.116 M C) [C6H12] = 0.241 M, [CH3C5H9] = 0.034 M D) [C6H12] = 0.253 M, [CH3C5H9] = 0.022 M

C) [C6H12] = 0.241 M, [CH3C5H9] = 0.034 M

39) In a reaction mixture containing only reactants, what is the value of Q? A) -1 B) 1 C) ∞ D) 0 E) It cannot be determined without concentrations.

D) 0

103) The equilibrium constant is given for one of the reactions below. Determine the value of the missing equilibrium constant. 2 HD(g) ⇌H2(g) + D2(g) Kc= 0.286 H2(g) + 6 D2(g) ⇌12 HD(g)Kc= ? A) 0.00048 B) 1.2 C) 1.62 D) 2075 E) 0.81

D) 2075

1) Which of the following statements is false? A) When K >> 1, the forward reaction is favored and essentially goes to completion. B) When K << 1, the reverse reaction is favored and the forward reaction does not proceed to a great extent. C) When K ≈ 1, neither the forward or reverse reaction is strongly favored, and about the same amount of reactants and products exist at equilibrium. D) K >> 1 implies that the reaction is very fast at producing products. E) None of the above

D) K >> 1 implies that the reaction is very fast at producing products. Note: If K = 1, the equilibrium mixture contains almost equal amounts of reactants and products. If K>>1 the forward reaction is favored and essentially goes to completion If K << 1 the reverse reaction is favored.

112) What will happen to the following exothermic reaction at equilibrium if the pressure is raised? N2(g) + 3H2(g) ⇌2NH3(g) A) Less NH3 will be produced. B) More N2 and H2 will be produced. C) There will be no change in concentrations. D) More NH3 will be produced.

D) More NH3 will be produced. Note: Changing the pressure means there will be a shift towards the side with the least number of moles.

58) Consider the following reaction at equilibrium. What effect will adding more SO3 have on the system? SO2(g) + NO2(g) ⇌SO3(g) + NO(g) A) The reaction will shift in the direction of products. B) The reaction will shift to decrease the pressure. C) No change will occur since SO3 is not included in the equilibrium expression. D) The reaction will shift in the direction of reactants. E) The equilibrium constant will decrease.

D) The reaction will shift in the direction of reactants.

63) Consider the following reaction at equilibrium. What effect will reducing the volume of the reaction mixture have on the system? Xe(g) + 2 F2(g) →XeF4(g) A) The reaction will shift to the left in the direction of reactants. B) The equilibrium constant will increase. C) No effect will be observed. D) The reaction will shift to the right in the direction of products. E) The equilibrium constant will decrease.

D) The reaction will shift to the right in the direction of products.

59) Consider the following reaction at equilibrium. What effect will adding more H2S have on the system? 2 H2S(g) + 3 O2(g) ⇌2 H2O(g) + 2 SO2(g) A) The reaction will shift to the left. B) No change will be observed. C) The equilibrium constant will decrease. D) The equilibrium constant will increase. E) The reaction will shift in the direction of products.

E) The reaction will shift in the direction of products

67) Consider the following reaction at equilibrium. What effect will increasing the temperature have on the system? Fe3O4(s) + CO(g) ⇌3 FeO(s) + CO2(g) ΔH°= +35.9 kJ A) The reaction will shift to the left in the direction of reactants. B) The equilibrium constant will increase. C) The equilibrium constant will decrease. D) No effect will be observed. E) The reaction will shift to the right in the direction of products.

E) The reaction will shift to the right in the direction of products.

43) Consider the following reaction and its equilibrium constant: I2(g) + Br2(g) ⇌2 IBr(g) Kc= 1.1 × 10^2 A reaction mixture contains 0.41 M I2, 0.27 M Br2 and 3.5 M IBr. Which of the following statements is true concerning this system? A) The reaction will shift in the direction of products. B) The reaction will shift in the direction of reactants. C) The reaction quotient will decrease. D) The equilibrium constant will increase. E) The system is at equilibrium.

E) The system is at equilibrium.

3) Give the direction of the reaction, if K << 1. A) The forward reaction is favored. B) The reverse reaction is favored. C) Neither direction is favored. D) If the temperature is raised, then the forward reaction is favored. E) If the temperature is raised, then the reverse reaction is favored.

If K << 1 the reverse reaction is favored.

6) Express the equilibrium constant for the following reaction. PCl5(g) ⇌PCl3(g) + Cl2(g)

K= [PCl3][Cl2]/[PCl5]

25) Express the equilibrium constant for the following reaction. P4(s) + 5 O2(g) ⇌P4O10(s)

Kc=[O2]^5 Note: Remember not to include solids

4) Express the equilibrium constant for the following reaction. 2CH3Cl(g) + Cl2(g) ⇌ 2CH2Cl2(g) + H2(g) a.) K = [CH3Cl]^2[Cl2]/[CH2Cl2]^2[H2] b.) K = [CH2Cl2]^2[H2]/[CH3Cl]^2[Cl2] c.) K = [CH2Cl2][H2]/[CH3Cl][Cl2] d.) K = [CH3Cl][Cl2]/[CH2Cl2][H2] e.) K = [CH3Cl]^1/2[Cl2]/[CH2Cl2]^1/2[H2]

b.) K = [CH2Cl2]^2[H2]/[CH3Cl]^2[Cl2]

38) Which of the following statements are true? A) Dynamic equilibrium occurs when the rate of the forward reaction equals the rate of the reverse reaction. B) The equilibrium constant for the forward reaction is equal to the equilibrium constant for the reverse reaction. C) A reaction quotient (Q) larger than the equilibrium constant (K) means that the reaction will favor the production of more products. D) Dynamic equilibrium indicates that the amount of reactants and products are equal.E) All of the above are true.

A) Dynamic equilibrium occurs when the rate of the forward reaction equals the rate of the reverse reaction.

111) What will happen to the following endothermic reaction in equilibrium if the temperature is raised? N2O4(g)⇌2NO2(g) A) More NO2 will be produced. B) Less NO2 will be produced. C) More N2O4 will be produced. D) There will be no change in concentrations.

A) More NO2 will be produced. Note: Temperature is treated like a reactant

60) Consider the following reaction at equilibrium. What effect will adding some C have on the system? CO2(g) + C(graphite) ⇌2 CO(g) A) No effect will be observed since C is not included in the equilibrium expression. B) The equilibrium constant will decrease. C) The reaction will shift to the left in the direction of reactants. D) The equilibrium constant will increase. E) The reaction will shift to the right in the direction of products.

A) No effect will be observed since C is not included in the equilibrium expression.

2) Give the direction of the reaction, if K >> 1. A) The forward reaction is favored. B) The reverse reaction is favored. C) Neither direction is favored. D) If the temperature is raised, then the forward reaction is favored. E) If the temperature is raised, then the reverse reaction is favored.

A) The forward reaction is favored.

110) The equilibrium constant (Kc) for the reaction N2O4(g) ⇌2 NO2(g) is 5.85 × 10-3 at 10°C. A reaction mixture has 0.025 M of N2O4 and 0.033 M of NO2 at time t. What statement is correct for this reaction at time t? A) The reaction goes to the left. B) The reaction is in equilibrium. C) The reaction goes to the right. D) The reaction is very slow.

A) The reaction goes to the left.

65) Consider the following reaction at equilibrium. What effect will reducing the pressure of the reaction mixture have on the system? Xe(g) + 2 F2(g) →XeF4(g) A) The reaction will shift to the left in the direction of reactants. B) The equilibrium constant will increase. C) No effect will be observed. D) The reaction will shift to the right in the direction of products. E) The equilibrium constant will decrease.

A) The reaction will shift to the left in the direction of reactants.

68) Consider the following reaction at equilibrium. What effect will decreasing the temperature have on the system? CO2(g) + 2 H2O(l) ⇌CH4(g) + 2 O2(g) ΔH° = +890 kJ A) The reaction will shift to the left in the direction of reactants. B) The equilibrium constant will decrease. C) The equilibrium constant will increase. D) The reaction will shift to the right in the direction of products. E) No effect will be observed.

A) The reaction will shift to the left in the direction of reactants.

64) Consider the following reaction at equilibrium. What effect will increasing the pressure of the reaction mixture have on the system? 2 H2S(g) + 3 O2(g) ⇌2 H2O(g) + 2 SO2(g) A) The reaction will shift to the right in the direction of products. B) No effect will be observed. C) The reaction will shift to the left in the direction of reactants. D) The equilibrium constant will decrease .E) The equilibrium constant will increase.

A) The reaction will shift to the right in the direction of products.

105) Which is true for a chemical reaction at equilibrium? A) There are no observable changes, but microscopic processes continue. B) The reaction has stopped. C) The reaction proceeds in forward direction. D) The molecules have stopped moving.

A) There are no observable changes, but microscopic processes continue.

99) The equilibrium constant is equal to 5.00 at 1300 K for the reaction: 2 SO2(g) + O2(g) ⇌2 SO3(g) If initial concentrations are [SO2] = 6.00 M, [O2] = 0.45 M, and [SO3] = 9.00 M, the system is A) at equilibrium. B) not at equilibrium and will remain in an unequilibrated state. C) not at equilibrium and will shift to the left to achieve an equilibrium state. D) not at equilibrium and will shift to the right to achieve an equilibrium state.

A) at equilibrium.