CHAPTER 15: CHEMICAL EQUILIBRIUM

29) Which reaction will shift to the right in response to a decrease in volume? A) N2 (g) + 3H2 (g) 2NH3 (g) B) H2 (g) + Cl2 (g) 2 HCl (g) C) 2 SO3 (g) 2 SO2 (g) + O2 (g) D) 2HI (g) H2 (g) + I2 (g) E) 2 Fe2O3 (s) 4 Fe (s) + 3O2 (g)

A) N2 (g) + 3H2 (g) 2NH3 (g)

3) Which one of the following will change the value of an equilibrium constant? A) changing temperature B) adding other substances that do not react with any of the species involved in the equilibrium C) varying the initial concentrations of reactants D) varying the initial concentrations of products E) changing the volume of the reaction vessel

A) changing temperature

22) The equilibrium constant for the gas phase reaction 2SO2 (g) + O2 (g) 2SO3 (g) is Keq = 2.80 × 102 at 999 K. At equilibrium, ________. A) products predominate B) reactants predominate C) roughly equal amounts of products and reactants are present D) only products are present E) only reactants are present

A) products predominate

23) The equilibrium constant for the gas phase reaction 2NH3 (g) N2 (g) + 3H2 (g) is Keq = 230 at 300 °C. At equilibrium, ________. A) products predominate B) reactants predominate C) roughly equal amounts of products and reactants are present D) only products are present E) only reactants are present

A) products predominate

6) The equilibrium-constant expression depends on the ________ of the reaction. A) stoichiometry B) mechanism C) stoichiometry and mechanism D) the quantities of reactants and products initially present E) temperature

A) stoichiometry

11) The Keq for the equilibrium below is 5.4 × 1013 at 480.0 °C. 2NO (g) + O2 (g) 2NO2 (g) What is the value of Keq at this temperature for the following reaction? 2NO2 (g) 2NO (g) + O2 (g) A) 5.4 × 10-13 B) 1.9 × 10-14 C) 5.4 × 1013 D) 5.66 × 10-3 E) none of the above

B) 1.9 × 10-14

10) The Keq for the equilibrium below is 7.52 × 10-2 at 480.0 °C. 2Cl2 (g) + 2H2O (g) 4HCl (g) + O2 (g) What is the value of Keq at this temperature for the following reaction? 2HCl (g) + O2 (g) Cl2 (g) + H2O (g) A) 13.3 B) 3.65 C) -0.0376 D) 5.66 × 10-3 E) 0.274

B) 3.65

2) Which one of the following is true concerning the Haber process? A) It is a process used for shifting equilibrium positions to the right for more economical chemical synthesis of a variety of substances. B) It is a process used for the synthesis of ammonia. C) It is another way of stating Le Châtelier's principle. D) It is an industrial synthesis of sodium chloride that was discovered by Karl Haber. E) It is a process for the synthesis of elemental chlorine.

B) It is a process used for the synthesis of ammonia.

30) Based on Le Châtelier's principle, increasing pressure at constant temperature in the following reaction will not change the concentrations of reactants and products. A) N2O4 (g) 2NO2 (g) B) N2 (g) + O2 (g) 2NO (g) C) N2 (g) + 2O2 (g) 2NO2 (g) D) N2 (g) + 3H2 (g) 2NH3 (g) E) 2N2 (g) + O2 (g) 2N2O (g)

B) N2 (g) + O2 (g) 2NO (g)

25) At 400 K, the equilibrium constant for the reaction Br2 (g) + Cl2 (g) 2BrCl (g) is Kp = 7.0. A closed vessel at 400 K is charged with 1.00 atm of Br2 (g), 1.00 atm of Cl2 (g), and 2.00 atm of BrCl (g). Use Q to determine which of the statements below is true. A) The equilibrium partial pressures of Br2, Cl2, and BrCl will be the same as the initial values. B) The equilibrium partial pressure of BrCl (g) will be 4.00 atm. C) The equilibrium partial pressure of Br2 will be greater than 1.00 atm. D) At equilibrium, the total pressure in the vessel will be less than the initial total pressure. E) The reaction will go to completion since there are equal amounts of Br2 and Cl2.

B) The equilibrium partial pressure of BrCl (g) will be 4.00 atm.

4) Which of the following expressions is the correct equilibrium-constant expression for the equilibrium between dinitrogen tetroxide and nitrogen dioxide? N2O4 (g) 2NO2 (g) A) B) C) D) E)

B) [NO2]^2 / [N2O4]

32) Consider the following reaction at equilibrium: 2NH3 (g) N2 (g) + 3H2 (g) Le Châtelier's principle predicts that the moles of in the reaction container will increase with ________. A) some removal of from the reaction vessel (V and T constant) B) a decrease in the total pressure (T constant) C) addition of some to the reaction vessel (V and T constant) D) a decrease in the total volume of the reaction vessel (T constant) E) an increase in total pressure by the addition of helium gas (V and T constant)

B) a decrease in the total pressure (T constant)

21) The equilibrium constant for the gas phase reaction N2 (g) + 3H2 (g) 2NH3 (g) is Keq = 4.34 × 10-3 at 300 °C. At equilibrium, ________. A) products predominate B) reactants predominate C) roughly equal amounts of products and reactants are present D) only products are present E) only reactants are present

B) reactants predominate

24) The equilibrium constant for the gas phase reaction 2SO3 (g) 2SO2 (g) + O2 (g) is Keq = 3.6 × 10-3 at 999 K. At equilibrium, ________. A) products predominate B) reactants predominate C) roughly equal amounts of products and reactants are present D) only products are present E) only reactants are present

B) reactants predominate

1) At equilibrium, ________. A) all chemical reactions have ceased B) the rates of the forward and reverse reactions are equal C) the rate constants of the forward and reverse reactions are equal D) the value of the equilibrium constant is 1 E) the limiting reagent has been consumed

B) the rates of the forward and reverse reactions are equal

12) The Keq for the equilibrium below is 50. H2 (g) + I2 (g) 2HI (g) What is the value of Keq for the following reaction? 2HI (g) H2 (g) + I2 (g) A) 100 B) 0.50 C) 0.020 D) 2500 E) -50

C) 0.020

13) The Keq for the equilibrium below is 50. H2 (g) + I2 (g) 2HI (g) What is the value of Keq for the following reaction? H2 (g) + I2 (g) HI (g) A) 25 B) 2500 C) 7.07 D) 100 E) -50

C) 7.07

19) The expression for for the reaction below is ________. 4CuO (s) + CH4 (g) CO2 (g) + 4Cu (s) + 2H2O (g)

C) PCO2 PH2O^2 / PCH4

15) Which of the following expressions is the correct equilibrium-constant expression for the reaction below? 2SO2 (g) + O2 (g) 2SO3 (g) A) [SO3] / [SO2][O2] B) [SO2] / [SO3] C) [SO3]2 / [SO2]2[O2] D) [SO3]2 / [SO2]2[O2]2 E) [SO3] / [SO2][O2]2

C) [SO3]2 / [SO2]2[O2]

34) Consider the following reaction at equilibrium. 2CO2 (g) 2CO (g) + O2 (g) ΔH° = -514 kJ Le Châtelier's principle predicts that the equilibrium partial pressure of CO (g) can be maximized by carrying out the reaction ________. A) at high temperature and high pressure B) at high temperature and low pressure C) at low temperature and low pressure D) at low temperature and high pressure E) in the presence of solid carbon

C) at low temperature and low pressure

14) Given the following reaction at equilibrium, if Kc = 1.90 × 1019 at 25.0 °C, Kp = ________. H2 (g) + Br2 (g) 2 HBr (g) A) 5.26 × 10-20 B) 1.56 × 104 C) 6.44 × 105 D) 1.90 × 1019 E) none of the above

D) 1.90 × 1019

7) The equilibrium constant for reaction 1 is K. The equilibrium constant for reaction 2 is ________. (1) SO2 (g) + (1/2) O2 (g) SO3 (g) (2) 2SO3 (g) 2SO2 (g) + O2 (g) A) K2 B) 2K C) 1/2K D) 1/K2 E) -K2

D) 1/K2

28) Which reaction will shift to the left in response to a decrease in volume? A) 2HI (g) H2 (g) + I2 (g) B) H2 (g) + Cl2 (g) 2 HCl (g) C) N2 (g) + 3H2 (g) 2 NH3 (g) D) 2 SO3 (g) 2 SO2 (g) + O2 (g) E) 4 Fe (s) + 3 O2 (g) 2 Fe2O3 (s)

D) 2 SO3 (g) 2 SO2 (g) + O2 (g)

20) The equilibrium-constant expression for the reaction Ti (s) + 2Cl2 (g) TiCl4 (l) is given by

D) [Cl2 (g)]-2

18) Which of the following expressions is the correct equilibrium-constant expression for the reaction below? HF (aq) + H2O (l) H3O+ (aq) + F- (aq) A) [HF][H2O] / [H3O+][F-] B) 1 / [HF] C) [H3O+][F-] / [HF][H2O] D) [H3O+][F-] / [HF] E) [F-] / [HF]

D) [H3O+][F-] / [HF]

16) Which of the following expressions is the correct equilibrium-constant expression for the reaction below? (NH4)2Se (s) 2NH3 (g) + H2Se (g) A) [NH3][H2Se] / [(NH4)2Se] B) [(NH4)2Se] / [NH3]2[H2Se] C) 1 / [(NH4)2Se] D) [NH3]2[H2Se] E) [NH3]2[H2Se] / [(NH4)2Se]

D) [NH3]2[H2Se]

35) The effect of a catalyst on an equilibrium is to ________. A) increase the rate of the forward reaction only B) increase the equilibrium constant so that products are favored C) slow the reverse reaction only D) increase the rate at which equilibrium is achieved without changing the composition of the equilibrium mixture E) shift the equilibrium to the right

D) increase the rate at which equilibrium is achieved without changing the composition of the equilibrium mixture

33) Consider the following reaction at equilibrium: 2CO2 (g) 2CO (g) + O2 (g) ΔH° = -514 kJ Le Châtelier's principle predicts that a decrease in temperature will ________. A) decrease the partial pressure of O2 (g) B) increase the partial pressure of CO2 (g) C) decrease the value of the equilibrium constant D) increase the value of the equilibrium constant E) decrease the partial pressure of CO

D) increase the value of the equilibrium constant

8) The equilibrium expression for Kp for the reaction below is ________. 2O3 (g) 3O2 (g)

E) PO2^3 / PO3^2

26) Which of the following statements is true? A) Q does not change with temperature. B) Keq does not change with temperature, whereas Q is temperature dependent. C) K does not depend on the concentrations or partial pressures of reaction components. D) Q does not depend on the concentrations or partial pressures of reaction components. E) Q is the same as Keq when a reaction is at equilibrium.

E) Q is the same as Keq when a reaction is at equilibrium.

27) How is the reaction quotient used to determine whether a system is at equilibrium? A) The reaction quotient must be satisfied for equilibrium to be achieved. B) At equilibrium, the reaction quotient is undefined. C) The reaction is at equilibrium when Q < Keq. D) The reaction is at equilibrium when Q > Keq. E) The reaction is at equilibrium when Q = Keq.

E) The reaction is at equilibrium when Q = Keq.

5) Which of the following expressions is the correct equilibrium-constant expression for the following reaction? CO2 (g) + 2H2 (g) CH3OH (g)

E) [CH3OH] / [CO2][H2]^2

17) Which of the following expressions is the correct equilibrium-constant expression for the reaction below? CO2 (s) + H2O (l) H+ (aq) + HCO3- (aq) A) [H+][HCO3-] / [CO2] B) [CO2] / [H+][HCO3-] C) [H+][HCO3-] / [CO2][H2O] D) [CO2][H2O] / [H+][HCO3-] E) [H+][HCO3-]

E) [H+][HCO3-]

31) In which of the following reactions would increasing pressure at constant temperature change the concentrations of reactants and products, based on Le Châteliers principle? A) N2 (g) + 3H2 (g) 2NH3 (g) B) N2O4 (g) 2NO2 (g) C) N2 (g) + 2O2 (g) 2NO2 (g) D) 2N2 (g) + O2 (g) 2 O (g) E) all of the above

E) all of the above

9) The equilibrium expression for Kp for the reaction below is ________. N2 (g) + O2 (g) 2NO (g)

E) none of the above