982 Chem Ch14 A1

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1) Consider the following exothermic reaction:

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

Which of the following changes would not increase the amount of NH3 produced from given quantities of N2and H2?

A) an increase in PB) a decrease in VC) removing some NH3 and reestablishing equilibriumD) an increase in TE) none of the above

Answer: D

2) To an equilibrium mixture of 2 SO2 (g) + O2 (g) 2 SO3 (g), some helium, an inert gas, is added at constantvolume. The addition of He causes the total pressure to double. Which of the following is true?

A) SO2 increases.B) The number of moles of O2 increases.C) SO3 increases.D) The number of moles of SO3 increases.E) The concentrations of all three gases are unchanged.

Answer: E

3) Consider the following equilibrium:

PCl5 (g) PCl3 (g) + Cl2 (g)

2.0 mol of PCl3 and 2.0 mol of Cl2 are placed in a 10.0 L flask at 300°C and allowed to come to equilibrium.Analysis shows 0.70 mol of Cl2 is present in the equilibrium mixture. Determine the value of Kc at thistemperature.

A) 0.38 B) 0.070 C) 0.70 D) 26 E) 0.038Answer: E

4) The reaction: 2 NO (g) + Cl2 (g) 2 NOCl (g) is allowed to reach equilibrium. Analysis of the equilibriummixture shows [NO] = 0.0574, [Cl2] = 0.126, and [NOCl] = 0.248. Calculate Kc for this reaction at thistemperature.

A) 148 B) 6.75 × 10-3 C) 2.92 × 10-3 D) 34.2 E) 1.00Answer: A

5) For the reaction SO2 (g) + Cl2 (g) SO2Cl2 (g), Kc = 55.5 at a certain temperature.If 1.00 mole of SO2 (g) and 1.00 mole of Cl2 (g) are placed in a 10.0-L container and allowed to come toequilibrium, what is the equilibrium concentration of SO2Cl2?

A) 0.034 B) 0.13 C) 0.066 D) 0.74 E) 0.87Answer: C

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6) A mixture is prepared with [CO] = 0.035, [Cl2] = 0.015, and [COCl2] = 0.95. It is known that Kc for the

equilibrium CO (g) + Cl2 (g) COCl2 (g) is 1.2 × 103 at 400°C. Predict what will happen.A) The reaction occurs in the reverse direction.B) The reaction occurs in the forward direction.C) The reaction is at equilibrium so no net reaction occurs.D) It is impossible to predict without more information.

Answer: A

7) If 0.01 mol CO(g) and 0.10 mol Cl2(g) are added to a 1.0 L flask, how many moles of CO(g) will there be atequilibrium?

CO (g) + Cl2 (g) COCl2 (g) Kc = 1.2 × 103

A) 3 × 10-3 B) 0.00 C) 9 × 10-5 D) -0.09 E) 0.01Answer: C

8) According to the following equilibrium,

2 HI (g) H2 (g) + I2 (g) H = -26.48 kJ/mol

the concentration of HI in equilibrium with H2 and I2 will decreaseA) by removing some iodine gas.B) by increasing the pressure of the system.C) by heating the system.D) by addition of a catalyst to the reaction.E) by adding some hydrogen gas.

Answer: A

9) The equilibrium constant for the reaction: ½ H2(g) + ½ I2(g) HI(g)

at 718 K is 7.07.Choice the correct describe about the Kc for this equation at 718 K.A) HI(g) ½ H2(g) + ½ I2(g) Kc=50 B) H2(g) + I2(g) 2 HI(g) Kc=0.141

C) HI(g) ½ H2(g) + ½ I2(g) Kc=7.07 D) H2(g) + I2(g) 2 HI(g) Kc=50

Answer: D

10) For the reaction 2 SO2 (g) + O2 (g) 2 SO4 (g), Kc = 2.7 × 102 at 960 K. What is the value of Kp for thisreaction? (R = 0.0821 L·atm/mol K)

A) 2.7 × 102 B) 2.1 × 104 C) 3.4 D) 0.023 E) 0.29Answer: C

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982 Chem Ch14 B1

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1) K = 0.25 for 2 NOBr (g) 2 NO (g) + Br2 (g). At the same T and P, what is the K for NO +12

Br2 NOBr?

A) 1.0 B) 2.0 C) 0.50 D) 0.63 E) 4.0Answer: B

2) Which direction will the following reaction (in a 5.0 L flask) proceed if some carbon dioxide is removed?

CaCO3 (s) CaO (s) + CO2 (g) Kp = 1.9 × 10-23

A) to the rightB) to the leftC) The equilibrium position will not change because the other components are solids.D) The equilibrium position will not change because there is an excess of calcium carbonate.E) The equilibrium position will not change because the system is closed.

Answer: A

3) The value of Kp for the reaction 2 NO2 (g) N2O4 (g) is 1.52 at 319 K. What is the value of Kp at this

temperature for the reaction 12

N2O4 (g) NO2 (g)?

A) -0.76 B) 0.811 C) 0.58 D) 1.23 E) 0.76Answer: B

4) For the system CaO (s) + CO2 (g) CaCO3 (s), the equilibrium constant expression isA) CaO [CO2] / CaCO3B) 1/ CO2C) 1/ CaO CO2D) CO2E) CaCO3 / CaO CO2

Answer: B

5) The value of Kc is changed whenA) a catalyst is added.B) the volume of the system is changed.C) the temperature of the system is changed.D) the pressure of the system is changed.E) the concentration of reactants are changed.

Answer: C

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6) Consider the reaction below:

CO (g) + H2O (g) CO2 (g) + H2 (g) H° = -41 kJ

All of the following changes would shift the equilibrium to the right except one. Which one would not cause theequilibrium to shift to the right?

A) Remove some CO2.B) Increase the partial pressure of H2O.C) Add some CO.D) Decrease the container volume.E) Decrease the temperature.

Answer: D

7) For the reaction: H2 + Br2 2 HBr, Kc = 7.5 × 102 at a certain temperature.If 1 mole each of H2 and Br2 are placed in 1-L flask, what is the concentration of H2 at equilibrium?

A) 0.07 B) 0.46 C) 0.04 D) 0.93 E) 0.96Answer: A

8) Which statement below is TRUE?A) The rate of the forward reaction is greater than the rate of the reverse reaction at equilibrium.B) The rate of the forward reaction is equal to the rate of the reverse reaction at equilibrium.C) The rate of the forward reaction is slow at first, then increases to a maximum at equilibrium.D) Equilibria and kinetics cannot be compared.

Answer: B

9) If 0.01 mol CO(g) and 0.10 mol Cl2(g) are added to a 1.0 L flask, how many moles of CO(g) will there be atequilibrium?

CO (g) + Cl2 (g) COCl2 (g) Kc = 1.2 × 103

A) 9 × 10-5 B) 0.01 C) 3 × 10-3 D) 0.00 E) -0.09Answer: A

10) Consider the following equilibrium:

PCl5 (g) PCl3 (g) + Cl2 (g)

5.0 moles of PCl5 are placed in a 10.0 L flask at 200°C and allowed to come to equilibrium. Analysis shows that1.0 mole of Cl2 is present in the equilibrium mixture. Determine the value of Kc at 200°C.

A) 0.25 B) 0.020 C) 0 D) 0.025 E) 0.033Answer: D

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982 Chem Ch14 C1

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1) The value of Kp for the reaction 2 NO2 (g) N2O4 (g) is 1.52 at 319 K. What is the value of Kp at this

temperature for the reaction 12

N2O4 (g) NO2 (g)?

A) 0.58 B) -0.76 C) 0.76 D) 1.23 E) 0.811Answer: E

2) The equilibrium constant for the following reaction is given. Assuming that the forward and reverse reactionscan be written as elementary steps, which statement below is true for this reaction at equilibrium?

A B + C Kc = 150

A) The rate constants for this reaction cannot be determined based on the equilibrium constant.B) The rate constant for the forward reaction is smaller than that for the reverse reaction.C) The rate constant for the forward reaction is 150 times greater than that for the reverse reaction.D) The rate constant for the reverse reaction is 150 times greater than that for the forward reaction.E) The rate constants for the forward and reverse reactions are identical at equilibrium.

Answer: D

3) The ionization of water by ammonia is shown below.

NH3 (aq) + H2O (l) NH4+ (aq) + OH- (aq) Kc = 1.78 × 10-5 at 25°C.

Calculate the concentration of OH-(aq) in a 0.1 M ammonia solution at equilibrium.A) 1.78 × 10-6 MB) 1.33 × 10-5 MC) 1.33 × 10-3 MD) 6.65 × 10-4 ME) 0.100 M

Answer: C

4) For the gaseous system,

2 H2S + 3 O2 2 H2O + SO2,

how is Kp related to Kc at a given temperature?A) greater than B) less than C) equal to D) unrelated to

Answer: B

5) For which of the following values of Kc will the equilibrium mixture consist almost entirely of reactants?

A) 4 × 108 B) 1.00 C) 0.030 D) 1 × 10-10 E) 30Answer: D

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6) Balance the following equation and determine the equilibrium constant expression, Kc.

C ( s) + H2O (g) C2H5OH (g) + O2 (g) (not balanced)

A)C2H5OH O2

H2O

B) [C2H5OH] [O]2

C)C2H5OH O2

C H2O

D)C H2O

C 2 H2O 3

E)C2H5OH O2

H2O 3

Answer: E

7) Consider the reaction below:

2 SO3 (g) 2 SO2 (g) + O2 (g) H° = +198 kJ

All of the following changes would shift the equilibrium to the left except one. Which one would not cause theequilibrium to shift to the left?

A) Decrease the temperature.B) Add a catalyst that speeds up the decomposition of SO3.C) Add some SO2.D) Remove some SO3.E) Decrease the container volume.

Answer: B

8) Consider the following reaction at a particular temperature :

NO2(g) + N2O(g) 3 NO(g)

Given that the equilibrium concentrations are [NO2] = 1.25 M, [N2O] = 1.80 M, and [NO] =0.0015 M, what isthe value of the equilibrium constant Kc?

A) 6.7 × 10-4 B) 2.0 ×10-3 C) 6.7 × 108 D) 1.5 × 10-9

Answer: D

9) How many of the following factors affect the numerical value of K?

pressure initial concentrationvolume temperaturechemical equation

A) 0 B) 1 C) 2 D) 3 E) 4Answer: C

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10) A sample of phosgene, COCl2(g), is introduced into a constant-volume vessel at 395 °C

and observed to exert an initial pressure of 0.351 atm. When equilibrium is establishedfor the reaction

CO(g) + Cl2(g) COCl2(g) Kp = 22.5

what will be the total gas pressure?A) 0.332 atm B) 0.456 atm C) 0.174 atm D) 0.825 atm

Answer: B

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982 Chem Ch14 D1

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1) For the reaction 2 SO2 (g) + O2 (g) 2 SO4 (g), Kc = 2.7 × 102 at 960 K. What is the value of Kp for thisreaction? (R = 0.0821 L·atm/mol K)

A) 0.023 B) 2.7 × 102 C) 0.29 D) 2.1 × 104 E) 3.4Answer: E

2) Consider the following reaction at a particular temperature :

NO2(g) + N2O(g) 3 NO(g)

Given that the equilibrium concentrations are [NO2] = 1.25 M, [N2O] = 1.80 M, and [NO] =0.0015 M, what isthe value of the equilibrium constant Kc?

A) 6.7 × 108 B) 2.0 ×10-3 C) 1.5 × 10-9 D) 6.7 × 10-4

Answer: C

3) Determine the value of Kc for the following reaction given the Kp.

CO (g) + Cl2 (g) COCl2 (g) Kp = 15.0 at 300°C (R = 0.0821 L·atm/molK)

A) 3.14 B) 0.319 C) 706 D) 369 E) 1.42 × 10-3

Answer: C

4) The equilibrium constant for the following reaction is given. Assuming that the forward and reverse reactionscan be written as elementary steps, which statement below is true for this reaction at equilibrium?

A B + C Kc = 150

A) The rate constant for the reverse reaction is 150 times greater than that for the forward reaction.B) The rate constant for the forward reaction is 150 times greater than that for the reverse reaction.C) The rate constants for this reaction cannot be determined based on the equilibrium constant.D) The rate constant for the forward reaction is smaller than that for the reverse reaction.E) The rate constants for the forward and reverse reactions are identical at equilibrium.

Answer: A

5) For the reaction: H2 + Br2 2 HBr, Kc = 7.5 × 102 at a certain temperature.If 1 mole each of H2 and Br2 are placed in 1-L flask, what is the concentration of H2 at equilibrium?

A) 0.46 B) 0.96 C) 0.07 D) 0.04 E) 0.93Answer: C

6) For the system 2A (g) + B( g) 2C (g), if the initial concentration of pure C is 1.00 M, the equilibriumconcentration is 0.40 M. What is the value of K?

A) 5.0 B) 0.45 C) 0.67 D) 1.5 E) 2.2Answer: D

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7) The concentration equilibrium constant has units ofA) atm.B) m.C) M.D) The units of Kc depend on the balanced chemical equation.E) Kc is unitless.

Answer: E

8) What is the total pressure in atmospheres at equilibrium above a 5.0 L flask containing excess CaCO3(s) andCaO(s)?

CaCO3 (s) CaO (s) + CO2 (g) Kp = 1.9 x 10-23

A) 1.9 × 10-23

B) 3.8 × 10-24

C) 3.8 × 10-23

D) 5.3 ×1022E) More information is needed to answer this question.

Answer: A

9) Which direction will the following reaction (in a 5.0 L flask) proceed if a catalyst is added to the system?

CaCO3 (s) CaO (s) + CO2 (g) Kp = 1.9 × 10-23

A) to the rightB) to the leftC) The equilibrium position will not change but the rate will increase.D) The equilibrium position will not change but the concentrations of everything will increase.E) It is impossible to tell without more information.

Answer: C

10) Balance the following equation and determine the correct equilibrium constant expression, Kc.

C2H2 (g) + H2 (g) C2H6 (g) (not balanced)

A)C2H6

C2H2 H2 2

B)C2H2 H2 2

[C2H6]

C)[C2H6][C2H2]

D)[C2H2][C2H6]

E)C2H6 2

C2H2 2 H2

Answer: A

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982 Chem Ch14 E1

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1) Which direction will the following reaction (in a 5.0 L flask) proceed if some carbon dioxide is removed?

CaCO3 (s) CaO (s) + CO2 (g) Kp = 1.9 × 10-23

A) to the rightB) to the leftC) The equilibrium position will not change because the other components are solids.D) The equilibrium position will not change because there is an excess of calcium carbonate.E) The equilibrium position will not change because the system is closed.

Answer: A

2) A sample of phosgene, COCl2(g), is introduced into a constant-volume vessel at 395 °C

and observed to exert an initial pressure of 0.351 atm. When equilibrium is establishedfor the reaction

CO(g) + Cl2(g) COCl2(g) Kp = 22.5

what will be the total gas pressure?A) 0.825 atm B) 0.456 atm C) 0.332 atm D) 0.174 atm

Answer: B

3) Kp for the reaction CaCO3 (s) CaO (s) + CO2 (g) is 0.88 at 600°C.If a 15.0-g sample of CaCO3 is put into a 10.0 L container and heated to 600°C, what percent of the CaCO3reacts?

A) 100 B) 18.1 C) 36.1 D) 81.9 E) 13.1Answer: D

4) If 0.22 atm H2S(g) are added to a 1.0 L flask containing an excess of I2(s), what will be the equilibriumconcentration of HI?

H2S (g) + I2 (s) HI (g) + S (s) Kp = 1.34 × 10-5 at 60°C

A) 8.6 × 10-4

B) 6.9 × 10-3

C) 3.0 × 10-6

D) 1.7 × 10-3E) More information is needed to answer this question.

Answer: D

5) The value of Kc is changed whenA) a catalyst is added.B) the concentration of reactants are changed.C) the temperature of the system is changed.D) the volume of the system is changed.E) the pressure of the system is changed.

Answer: C

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6) If the equilibrium concentrations found in the reaction:

2 A (g) + B (g) 2 C (g),

are [A] = 0.30 M, [B] = 0.10 M, and [C] = 0.20 M, calculate the value of Kc.A) 4.4 B) 3.3 C) 0.21 D) 0.23 E) 6.7

Answer: A

7) Which direction will the following reaction (in a 5.0 L flask) proceed if the pressure of CO2(g) is 1.0 atm?

CaCO3 (s) CaO (s) + CO2 (g) Kp = 1.9 × 10-23

A) to the right because Q > KpB) to the left because Q < KpC) to the right because Q < KpD) to the left because Q > KpE) The reaction is at equilibrium.

Answer: D

8) Which direction will the following reaction (in a 5.0 L flask) proceed if a catalyst is added to the system?

CaCO3 (s) CaO (s) + CO2 (g) Kp = 1.9 × 10-23

A) to the rightB) to the leftC) The equilibrium position will not change but the concentrations of everything will increase.D) The equilibrium position will not change but the rate will increase.E) It is impossible to tell without more information.

Answer: D

9) Which is not correct concerning equilibrium?A) The rates of the forward and reverse reactions are the same.B) Either the reactants or the products of a reaction could be used to attain equilibrium for a reversible

reaction.C) At equilibrium, the rates of the forward and reverse reaction become zero.D) The ratio of the concentrations of products and reactants, raised to appropriate powers, is a constant.E) The concentration of reactants and products are no longer changing.

Answer: C

10) Carbon monoxide and chlorine react to form phosgene, COCl2, which is used in the manufacture of pesticides,

herbicides, and plastics:

COCl2(g) CO(g) + Cl2(g) Kc = 1.2 x 103 at 668 K

How much of each substance, in moles, will there be at equilibrium in a reaction mixturethat initially has 0.0100 mol CO, 0.0100 mol Cl2, and 0.100 mol COCl2 in a 10.0-L flask?

A) all are incorrect B) CO:0.314 mol C) Cl2:0.026 mol D) COCl2:0.314 mol

Answer: A

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