R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02 ... · R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 4 / 63 9. Consider the following equilibrium… PCl

R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 1 / 63

Chemistry 12 Provincial Workbook

Unit 02: Chemical Equilibrium

Multiple Choice Questions 1. Consider the following...

Which of the following lists these equilibria from the one that most favours products to the one

that least favours products? A. I, II, III B. I, III, II C. II, III, I D. III, I, II 2. Consider the following equilibrium system...

4

Ni(s)+4CO(g) Ni CO (g), ΔH=- 603kJ

Which of the following statements is correct?

A. Increasing CO will increase eqK .

B. Increasing temperature will increase eqK .

C. Increasing temperature will decrease eqK .

D. Decreasing 4

Ni CO will decrease eqK .


3. Consider the equilibrium...

2 2 3 eqN (g)+3H (g) 2NH (g), K =64

A 1.0L container is filled with 0.28 mol 2N , 0.16 mol 2H and 0.54 mol 3NH . In which direction

will the reaction proceed and what will happen to the pressure of the system?

4. Consider the following equilibrium...

4 2 2 2NH NO (s) N (g)+2H O(g)

Which of the following correctly represents the 2H O at equilibrium?

A.

eq

2

2

KH O =

N

B.

eq

2

2

K1H O =

2 N

C.

eq 4 2

2

2

K NH NOH O =

N

D.

eq 4 2

2

2

K NH NOH O =

N

5. Consider the following equilibrium:

3 2 24NH (g) 5O (g) 4NO(g) 6H O(g) energy

Which of the following will cause the equilibrium to shift to the left?

A. adding 2H O(g)

B. removing some NO(g)

C. increasing the volume D. decreasing the temperature


6. Consider the following equilibrium…

2 22NO(g) O (g) 2NO (g) energy

When the volume of the container is increased, the equilibrium shifts to the…

A. left and eqK decreases

B. right and eqK increases

C. left and eqK remains constant

D. right and eqK remains constant


2 2 24HCl(g) O (g) 2H O(g) 2Cl (g) energy

The temperature of the equilibrium system is increased and a new equilibrium is established. The rates of the forward and reverse reactions for the new equilibrium compared to the original equilibrium have…

8. The value of eqK changes when…

A. a catalyst is added B. the temperature changes C. the surface area changes D. the concentration of reactants changes



5 3PCl (g) PCl (g) Cl(g)

A 1.00 L flask contains 0.0200 mol 5PCl , 0.0500 mol 3PCl and 0.0500 mol 2Cl at equilibrium.

The value of eqK is…

A. 0.125 B. 2.50 C. 5.00 D. 8.00 10. Consider the following equilibrium…

2 2 2N (g) 2O (g) 2NO (g)

Equal moles of 2N and 2O are added, under certain conditions, to a closed container. Which

of the following describes the changes in the reverse reaction which occur as the system proceeds toward equilibrium?

11. A chemical equilibrium is described as “dynamic” because… A. maximum randomness has been achieved B. the pressure and temperature do not change C. both reactants and products continue to form D. the concentrations of chemical species remain constant


12. Which of the following reactions results in an entropy increase?

A. 22C(s) O (g) 2CO(g)

B. 2 2 2 4N (g) 2H (g) N H (l)

C. 2 2 32SO (g) O (g) 2SO (g)

D. Ag (aq) Cl (aq) AgCl(s)


3 2 3 3CH COOH(aq) H O(l) CH COO (aq) H O (aq) heat

A stress was applied at time 1t and the data was plotted on the following graph…

The stress that was imposed at time 1t is the result of…

A. the addition of HCl

B. decreasing the temperature

C. the addition of 3NaCH COO

D. increasing the volume of the container


14. Consider the following potential energy diagram for an equilibrium system…

When the temperature of the system is increased, the equilibrium shifts to the…

A. left and the eqK increases

B. left and the eqK decreases

C. right and the eqK increases

D. right and the eqK decreases


3 2 eq2O (g) 3O (g), K 65

Initially, 0.10 mole of 3O and 0.10 mole of 2O are placed in a 1.0 L container. Which of the

following describes the changes in concentrations as the reaction proceeds toward equilibrium?


16. Which of the following applies to a chemical equilibrium?

I. Forward and reverse reaction rates are equal

II. Equilibrium can be achieved from either direction

III. Macroscopic properties are constant

A. I only B. I and II only C. II and III only D. I, II and III 17. In which of the following will the driving forces of minimum enthalpy and maximum

entropy oppose one another?

A. 22C(s) O (g) 2CO(g), H 221kJ

B. 2 2 22N (g) O (g) 2N O(g),ΔH 164kJ

C. 2 22CO(g) O (g) 2CO (g),ΔH 566kJ

D. 2 2 2 6 24CO (g) 6H O(g) 2C H (g) 7O (g), H 3122kJ

18. Ammonia, 3NH , is produced by the following reaction…

2 2 3N (g) 3H (g) 2NH (g) energy

Which of the following would result in the highest concentration of ammonia at equilibrium?

A. increasing the temperature and increasing the pressure B. decreasing the temperature and increasing the pressure C. increasing the temperature and decreasing the pressure D. decreasing the temperature and decreasing the pressure 19. Consider the following reaction…

2 4C(s) 2H (g) CH (g), H 74.8kJ

Which of the following will cause an increase in the value of eqK ?

A. increasing 2H

B. decreasing the volume C. finely powdering the C(s) D. decreasing the temperature



2 2H (g) I (g) 2HI(g)

At equilibrium 2H 0.00220mol/L , 2I 0.00220mol/L and HI 0.0156mol/L . The value

of eqK is…

A. 43.10x10

B. 21.99x10

C. 15.03x10

D. 33.22x10


22NOCl(g) 2NO(g) Cl (g)

A flask of fixed volume is initially filled with NOCl(g) , NO(g) and 2Cl (g) . When equilibrium is

reached, the pressure has increased. To reach equilibrium, the reaction proceeded to the…

A. left because Trial eqK was less than eqK

B. right because Trial eqK was less than eqK

C. left because Trial eqK was greater than eqK

D. right because Trial eqK was greater than eqK

22. In which of the following do both minimum enthalpy and maximum entropy factors

favour the reactants?

A. 2 2Cl (g) Cl (aq), H 25kJ

B. 2 2C(s) H O(l) CO(g) H (g), H 131kJ

C. 2 2 2 5 22CO (g) 3H O(g) C H OH(l) 3O (g), H 1239kJ

D. 2 3 2 2Na CO (s) HCl(aq) 2NaCl(aq) CO (g) H O(l), H 28kJ



2 2H (g) I (g) 2HI(g)

Which graph represents what happens when some HI is removed and a new equilibrium is established?


2 2 2CO(g) H O(g) CO (g) H (g), H 41kJ

What will cause a shift in the equilibrium?

A. adding a catalyst B. changing volume C. adding an inert gas D. changing temperature


25. The equilibrium expression for a reaction is…

6

eq 2 33

2

HK

Bi H S

The reaction could be…

A. 3

26H (aq) BiS(s) 2Bi (aq) 3H S(g)

B. 3

2 3 26H (aq) Bi S (s) 2Bi (aq) 3H S(g)

C. 3

2 2 32Bi (aq) 3H S(aq) Bi S (s) 6H (aq)

D. 3

2 2 32Bi (aq) 3H S(aq) Bi S (aq) 6H (aq)

26. Consider the following…

3 2 5 eqPCl (g) Cl (g) PCl (g), K 0.45 at 227°C

Initially, a 1.00L flask is filled with 30.100 mol PCl , 20.100 mol Cl , and 50.100 mol PCl at

227°C. Use trialK to predict the change in 2Cl as equilibrium is established.


27. Consider the following equilibrium reaction:

2 22ICI(g) I (g) Cl (g)

Some ICI is added to an empty flask. How do the reaction rates change as the system

approaches equilibrium?

Forward rate Reverse rate

A. increases increases

B. increases decreases

C. decreases increases

D. decreases decreases

28. In an equilibrium system, continuing microscopic changes indicate that the equilibrium

is… A. dynamic B. complete C. exothermic D. spontaneous 29. Consider the following equilibrium…

2 24CuO(s) energy 2Cu O(s) O (g)

The equilibrium will shift to the right as a result of…

A. adding CuO(s)

B. removing 2O (g)

C. adding a catalyst D. decreasing the temperature 30. Consider the following equilibrium…

2 2 3N (g) 3H (g) 2NH (g)

The volume of the system is decreased. The equilibrium shifts…

A. left since the reverse rate is greater than the forward rate B. left since the forward rate is greater than the reverse rate C. right since the reverse rate is greater than the forward rate D. right since the forward rate is greater than the reverse rate



3 2 22SO (g) 2SO (g) O (g), H 198kJ

When the temperature is increased, the equilibrium will shift…

A. left with eqK becoming larger

B. right with eqK becoming larger

C. left with eqK becoming smaller

D. right with eqK becoming smaller

32. Starting with equal concentrations of reactants, which of the following will be closest

to completion at equilibrium?

A. 2 2 eqCO(g) Cl (g) COCl (g), K 22

B. 2

3 2 5 eqPCl (g) Cl (g) PCl (g), K 2.9x10

C. 9

2 2 eqCO(g) Cl (g) COCl (g), K 4.5x10

D. 12

3 2 2 3 2 2 eqCH O (g) NO (g) CH O NO (g), K 2.1x10


2 2 42COF (g) CO (g) CF (g)

At equilibrium, a 1.00L container contains 4

27.07x10 mol COF , 3

21.00x10 mol CO , and 3

41.00x10 mol CF . What is the value of eqK ?

A. 47.07x10

B. 31.41x10

C. 0.500 D. 2.00


34. Consider the following reaction…

2 22ICI(g) I (g) Cl (g)

A closed container is initially filled with ICI(g) . What are the changes in the rate of the forward

reaction and 2I , as the system approaches equilibrium?

35. The entropy of a system is a term used to describe A. randomness B. heat content C. average kinetic energy D. stored chemical energy 36. Consider the following equilibrium…

2 2-

4Cu (aq) 4Br CuBr (aq)(aq) energy

blue colourless green

Which of the following will cause this equilibrium to change from blue to green?

A. adding NaBr(s)

B. adding 3NaNO (s)

C. adding a catalyst D. decreasing the temperature



2Ni(s) 4CO(g) Ni(CO) (l), H -160.8kJ

Which of the following will cause this equilibrium to shift to the left?

A. add some CO

B. decrease the volume

C. remove some 4Ni(CO)

D. increase the temperature 38. Consider the following equilibrium…

2 4 2N O (g) energy 2NO (g)

Which of the following shows the relationship between concentration and time as a result of

adding a catalyst at time 1t ?



2 2H S(g) I (s) 2HI(g) S(s)

What is the equilibrium expression for this reaction?

A.

2

eq

2

HIK

H S

B.

2

eq 2

H SK

HI

C.

2

eq

2 2

HI SK

H S I

D.

2 2

eq 2

H S IK

HI S


2 2 2 eqCO(g) H O(g) CO (g) H (g), K 5.0

At equilibrium, the CO 0.20mol/L , 2H O 0.30mol/L , and 2H 0.90mol/L . Calculate the

equilibrium 2CO .

A. 0.013mol/L

B. 0.066mol/L

C. 0.33mol/L

D. 1.0mol/L


41. Consider the following…

2 4 2 eqCO (g) CF (g) 2COF (g), K 0.50

In a reaction container the initial concentrations are…

2CO 0.50mol/L , 4CF 0.50mol/L , 2COF 0.30mol/L

To reach equilibrium, the reaction will proceed…

A. left since Trial eqK < eqK

B. left since Trial eqK > eqK

C. right since Trial eqK < eqK

D. right since Trial eqK > eqK

42. All chemical equilibriums must have…

A. eqK 1

B. reactants products

C. rate forward = rate reverse D. mass of reactants = mass of products 43. Consider the following equilibrium reaction…

2 2 24HCl(g) O (g) 2H O(g) 2Cl (g) 111.4kJ

For the forward reaction, how do enthalpy and entropy change?

Enthalpy Entropy

A. increases decreases

B. decreases decreases

C. increases increases

D. decreases increases



3 3CH Cl(aq) OH (aq) CH OH(aq) Cl (aq)

The equilibrium will shift to the left as a result of the addition of…

A. 3HNO

B. 3KNO

C. NaOH

D. 3CH Cl

45. Consider the following equilibrium at 25°C…

4Ni(s) 4CO(g) Ni(CO) (l)

For this reaction…

A. 4

eqK CO

B.

eq 4

1K

CO

C.

4

eq 4

Ni(CO)K

CO NI

D.

4

eq 4

Ni(CO)K

CO


2 2 4 eq2COF (g) CO (g) CF (g), K 2.00

At equilibrium, 2CO 0.050mol/L and 4CF 0.050mol/L . What is 2COF at equilibrium?

A. 0.0012mol/L

B. 0.035mol/L

C. 0.050mol/L

D. 0.22mol/L



0 09002 2 eqH O(g) Cl O(g) 2HOCl(g), K .

Initially, a 1.00L flask is filled with 0.100 mol of 2H O , 0.100 mol of 2Cl O and 0.100 mol of

HOCl . As equilibrium is established, the reaction proceeds to the…

A. left because Trial eqK > eqK

B. left because Trial eqK < eqK

C. right because Trial eqK > eqK

D. right because Trial eqK < eqK

48. What will cause the value of eqK for an endothermic reaction to increase?

A. increasing [products] B. decreasing [products] C. increasing the temperature D. decreasing the temperature 49. Consider the following equilibrium…

2 4 22N O (g) NO (g)

An equilibrium mixture contains 2

2 44.0x10 mol N O and 2

21.5x10 mol NO in a 1.0 L flask.

What is the value of eqK ?

A. 35.6x10

B. 13.8x10

C. 17.5x10

D. 21.8x10

50. Which of the factors below is not a condition necessary for equilibrium? A. a closed system B. a constant temperature C. equal forward and reverse reaction rates D. equal concentrations of reactants and products


51. In order for a chemical reaction to go to completion, how must the entropy and enthalpy change?

52. Consider the following equilibrium system…

4

2 2 3 eq2SO (g) O (g) 2SO (g),K 1.2x10

If additional 2SO is added to the system, what happens to the equilibrium and the value of

eqK ?


2 2 3N (g) 3H (g) 2NH (g)

Determine the changes in reaction rates as a catalyst is added.



3 22KClO (s) 2KCl(s) 3O (g)

Which of the following is the equilibrium constant expression?

A. 3

eq 2K O

B.

eq 3

2

1K

O

C.

2

3

eq 2 3

2

KClOK

KCl O

D.

2 3

2

eq 2

3

KCl OK

KClO


2 2 4 2CO (g) 2H O(g) CH (g) 2O (g)

Which of the options below indicates that the reactants are favoured?

A. eqK is zero

B. eqK is very large

C. eqK is slightly less than 1

D. eqK is slightly greater than 1


2 4 2N O (g) energy 2NO (g)

How are eqK and 2 4N O affected by the addition of neon (an inert gas) into the container at

constant volume.



2 eqCl (g) 2NO(g) 2NOCl(g), K 5.0

At equilibrium, 2Cl 1.0M and NO 2.0M . What is the NOCl at equilibrium?

A. 0.80 M B. 0.89 M C. 4.5 M D. 10 M 58. For the equilibrium system below…

2Cu(s) 2Ag (aq) 2Ag(s) Cu (aq)

We would know the system is at equilibrium because…

A. 2Cu Ag

B. 22 Cu Ag

C. the mass of Cu(s) remains constant

D. the mass of the entire system remains constant 59. For the reacting system…

?

2 22Li(s) 2H O(l) 2LiOH(aq) H (g), H 433kJ

What will entropy and enthalpy factors favour?



2 2 3N (g) 3H (g) 2NH (g)

If some Ne gas is added at a constant volume then how will 2N , 2H , and eqK be affected?

61. What is the effect of adding a catalyst to an equilibrium system?

A. The value of aE increases

B. The value of eqK increases

C. Forward and reverse rates increase D. The concentration of products increases 62. Consider the following equilibrium…

2 2

4 2 7 22CrO (aq) 2H (aq) Cr O H O(l)

What is the eqK expression?

A.

2 22

4

2

2 7

CrO H

Cr O

B.

2

2 7

2 22

4

Cr O

CrO H

C.

2

2 7

2

4

Cr O

2CrO 2H

D. 2

2 7 2

2 22

4

Cr O H O

CrO H


63. A container is initially filled with pure 3SO . After a period of time, the following

equilibrium is established…

25

2 2 3 eq2SO (g) O (g) 2SO (g), K 7.0x10

What does this equilibrium mixture contain?

A. mostly products B. mostly reactants

C. 3

5reactants and

2

5 products

D. equal amounts of reactants and products 64. Consider the following equilibrium…

10

2 2 eq2CO(g) O (g) 2CO (g), K 4.0x10

What is the value of eqK for 2 22CO (g) 2CO(g) O (g) ?

A. 104.0x10

B. 52.0x10

C. 45.0x10

D. 92.5x10


2 2H (g) Br (g) 2HBr(g), H 36kJ

How could the value of eqK be increased?

A. add 2H

B. add HBr C. increase the pressure D. reduce the temperature


66. A student places some HI (g) into a closed reaction container and the following equilibrium is established...

2 22HI(g) I (g)+H (g)

Which of the following describes the forward and reverse reaction rates?

67. Consider the equilibrium...

2 2H (g)+FeO(s) H O(g)+Fe(s)

The following chemicals are placed in separate 1.0 L containers.

In which container(s) will the equilibrium be established? A. Container III only B. Container IV only C. Containers I and II only D. Containers III and IV only


68. Consider the following...

2 2 6 12 6 2energy+6CO (g)+6H O(l) C H O (s)+6O g

Which of the following describes how enthalpy and entropy change in the forward direction?

69. Consider the following system at equilibrium...

2 6 2 3 2energy+N H CO (s) 2NH (g)+CO (g)

Which of the following is correct when the volume of the system is increased?

70. Consider the following system at equilibrium...

2 22NO(g)+O (g) 2NO (g)

Some 2O is added to the equilibrium. Which of the following describes how the forward and

reverse reaction rates change as a new equilibrium is being established?


71. Consider the following PE diagram…

Identify the activation energy for the forward uncatalyzed reaction. A. 1 B. 2 C. 3 D. 4 72. In which of the following will entropy and enthalpy factors favour the establishment of

an equilibrium?

A. ?

3 2CaCO (s) 178kJ CaO(s) CO (g)

B. ?

2 2Mg(s) 2HCl(aq) MgCl (aq) H (g) 425kJ

C. ?

2 2 42C(s) 2H (g) C H (g), H 52.3kJ

D. ?

2 6 2 2 22C H (g) 7O (g) 4CO (g) 6H O(g), H 1560kJ

73. (A09062003) Consider the following equilibrium…

2 3CO(g) 2H (g) CH OH(g), H 91kJ

Which of the factors below would increase the concentration of 3

CH OH at equilibrium?

A. an addition of CO

B. an increase in the volume C. a decrease in the pressure D. an increase in the temperature



3 2 5PCl (g) Cl (g) PCl (g)

If the volume of the system is decreased, how will the reaction rates in the new equilibrium

compare with the rates in the original equilibrium?


2 2H (g) I (g) 2HI(g), H 71.9kJ

colourless purple colourless

Which of the following would allow you to conclude that the system has reached equilibrium?

A. The pressure remains constant. B. The reaction rates become zero. C. The colour intensity remains constant. D. The system shifts completely to the right. 76. Consider the following equilibrium…

2 3 2Fe O (s) 3CO(g) 2Fe(s) 3CO (g)

Identify the equilibrium constant expression.

A.

3

2

eq 3

COK

CO

B.

2

eq

COK

CO

C.

3 2

2

eq 3

2 3

CO FeK

CO Fe O

D.

3

2 3

eq 3 2

2

Fe O COK

CO Fe



22NO(g) Cl (g) 2NOCl(g), H 77kJ

In which direction will the equilibrium shift and what happens to the value of eqK when the

temperature of the system is increased?


2 3CO(g) 2H (g) CH OH(g)

At equilibrium it was found that CO 0.105 mol/L , 2H 0.250 mol/L and

3CH OH 0.00261 mol/L . Which of the following is the equilibrium constant value?

A. 29.94x10

B. 0.398 C. 2.51 D. 10.0

79. In a certain reaction H 136kJ and aE 96kJ . Which of the following is true of its

reverse reaction?

A. The reverse reaction is exothermic and aE 40J

B. The reverse reaction is exothermic and aE 40kJ

C. The reverse reaction is endothermic and aE 96kJ

D. The reverse reaction is endothermic and aE 232kJ


80. Two experiments were performed involving the following equilibrium. The temperature was the same in both experiments.

2 2H (g) I (g) 2HI(g)

In experiment A, 1.0 M 2H and 1.0 M 2I were initially added to a flask and equilibrium was

established. In experiment B, 2.0 M HI was initially added to a second flask and equilibrium was established. Which of the following statements is always true about the equilibrium

concentrations?

A. 2H equals HI in experiment A

B. HI equals 22 H in experiment A

C. HI in experiment A equals HI in experiment B

D. HI in experiment A equals 2

1I

2 in experiment B

81. Which of the following reactions is accompanied by an increase in enthalpy?

A. 2 22NO(g) O (g) 2NO (g) 113kJ

B. 2 2 22H (g) O (g) 484kJ 2H O(g)

C. 3 2 22SO 2SO (g) O (g), H 197kJ

D. 2 24HCl(g) O (g) 2H O(g) 2Cl(g), H 111.4kJ

82. Two substances are mixed and no reaction occurs. With respect to enthalpy and

entropy, which of the following could explain why no reaction occurs?



2 2 3N (g) 3H (g) 2NH (g)

Which of the following diagrams represents what happens to the forward and reverse reaction

rates when the catalyst 3 4Fe O is added?

84. Temperature is gradually decreased then held constant in an exothermic equilibrium.

Which of the following represents the change in the reverse reaction rate?


85. If 2 4N O is placed in a flask at a constant temperature, which of the following is true as

the system approaches equilibrium?

2 4 2N O (g) 2NO (g)

colourless brown

A. The colour gets darker as 2NO increases

B. The colour gets lighter as 2NO decreases

C. The colour gets darker as 2 4N O increases

D. The colour gets lighter as 2 4N O decreases

86. The system above reaches equilibrium. Considering enthalpy and entropy factors,

which of the following is true with respect to the forward reaction?

2 4 2N O (g) 2NO (g)

colourless brown

A. The entropy is increasing and the reaction is exothermic B. The entropy is decreasing and the reaction is exothermic C. The entropy is increasing and the reaction is endothermic D. The entropy is decreasing and the reaction is endothermic 87. In which of the following reactions do the tendencies for minimum enthalpy and

maximum entropy both favour reactants?

A. ?

2 33O (g) 2O (g), H 285kJ

B. ?

2 2 3N (g) 3H (g) 2NH (g), H 92kJ

C. ?

2 22BrCl(g) Br (g) Cl (g), H 29.3kJ

D. ?

3 2CaCO (s) CaO(s) CO (g), H 175kJ



3 2CaCO (s) CaO(s) CO (g), H 175kJ

Which of the following diagrams best represents the change in the concentration of 2CO as

temperature is decreased at time 1t ?

89. The Haber Process is used to produce ammonia commercially according to the

following equilibrium…


Which of the following conditions will produce the highest yield of ammonia?

A. increase temperature and increase pressure B. increase temperature and decrease pressure C. decrease temperature and increase pressure D. decrease temperature and decrease pressure



2 2

2 7 4 2 eqCr O (aq) 2OH (aq) 2CrO (aq) H O(l), K 4.14

The concentration of ions at equilibrium was measured at a specific temperature and found to

be 2

7CrO 0.100M and OH 0.020M . What is the equilibrium 2

4CrO

A. 41.7x10 M

B. 33.1x10 M

C. 21.3x10 M

D. 12.0x10 M

91. In which of the following equilibria does the concentration of reactants equal the

concentration of products?

A. 2 4 2 eqN O (g) 2NO (g), K 0.71

B. 14

2 eqH (aq) OH (aq) H O(l), K 1.0x10

C. 2 2 2 eqCO (g) H (g) CO(g) H O(g), K 0.279

D. 2 2 2 eqSnO (s) 2H (g) Sn(s) 2H O(g),K 1.00


2 2C(s) H O(g) CO(g) H (g)

At equilibrium 24.0x10 mol CO , 2

21.0x10 mol H O ,and 21.0x10 mol C were present in a

1.0 L container. What is the value of eqK ?

A. 0.063 B. 0.16 C. 6.3 D. 16



2 2 42COF (g) CO (g) CF (g)

Initially, 0.12 M 2CO and 0.20 M 4CF are placed in a container. At equilibrium, it is found that

the 2COF is 0.040 M. What is the value of eqK ?

A. 0.089 B. 0.45 C. 8 0 D. 11 94. Which of the following represents the value for the activation energy of the forward

reaction in an equilibrium system?

A. a(forward) a(reverse)E E H

B. a(forward) a(reverse)E E H

C. a(forward) a(reverse)E ΔH E

D. a(forward) a(reverse)E ΔH E


3 2CaCO (s) CaO(s) CO (g)

In which of the flasks will this equilibrium be established?

A. 1, 2, 3 only B. 1, 2, 4 only C. 1, 3, 4 only D. 3, 4 only


96. Which of the following forward reactions demonstrates decreasing enthalpy and increasing entropy?

A. ?

2

1Hg(l) O (g) HgO(s), H 91kJ

2

B. ?

2 22HCl(g) H (g) Cl (g), H 185kJ

C. ?

22HgO(s) 2Hg(l) O (g), H 182kJ

D. ?

3 2 22SO (g) 2SO (g) O (g), H 200kJ

97. Which of the following would cause the amount of 3NH at equilibrium to increase?

3 2 2 24NH (g) 3O (g) 2N (g) 6H O(l), H 1530kJ

A. an increase in 2O

B. a decrease in volume C. a decrease in temperature D. an increase in temperature

98. What happens when 2O is added to the above system?

3 2 2 24NH (g) 3O (g) 2N (g) 6H O(l), H 1530kJ


99. If some 2O is injected into the system, what happens to the forward and reverse

reaction rates during the shift to re-establish equilibrium?

3 2 2 24NH (g) 3O (g) 2N (g) 6H O(l), H 1530kJ

100. Consider the equilibrium expression eq(01)K for reaction 01…

2 2 3

1SO (g) O (g) SO (g)

2

and the equilibrium expression eq(02)K for reaction 02…

3 2 22SO (g) O (g) 2SO (g)

How is eq(01)K related to eq(02)K ?

A. eq(01) eq(02)K K

B. 2

eq(02) eq(01)K K

C. eq(02)

eq(01)

1K

K

D.

2

eq(02)

eq(01)

1K

K


Written Questions 1. Consider the following equilibrium:

2 2 eqH (g) I (g) 2HI(g), K 49

A 1.00 L container is initially filled with 0.180 moles of HI. Calculate the concentration of HI at

equilibrium. (2 marks)

2. Consider the following diagram for a chemical system containing three substances

represented by A, B and C:

A. What feature of the graph indicates that the system reaches equilibrium? (1 mark)

B. Write a balanced equation for the equilibrium reaction. (2 marks)

C. Calculate eqK at equilibrium. (2 marks)


3. Describe how enthalpy and entropy change, in the forward direction, as an exothermic reaction reaches equilibrium. Explain your reasoning. (2 marks)

4. Consider the graph below representing the following equilibrium...

3 2 2 3 3 3 2CH CH CH CH (g) CH CH(CH ) (g)

n butane isobutane

Data for the graph was obtained from various equilibrium mixtures.

Calculate the value of eqK for the equilibrium. (2 marks)


5. Consider the following equilibrium system...


A 1.00 L container is filled with 5.0 mol 3NH and the system proceeds to equilibrium as

indicated by the graph.

A. Draw and label the graph for 2N and 2H . (2 marks)

B. Calculate the eqK for 2 2 3N (g) 3H (g) 2NH (g) energy (2 marks)

6. State Le Chatelier’s Principle. (2 marks)


2 2 24HCl(g) O (g) 2H O(g) 2Cl (g) energy

A. How does the entropy change in the forward direction? Explain your reasoning. (1 mark)


B. How does the enthalpy change in the forward direction? Explain your reasoning. (1 mark)


2

2 2 eqH (g) I (g) 2HI(g), K 1.2x10

A 2.0 L flask is filled with 0.10 mol HI. Calculate the concentration of 2H at equilibrium. (3

marks)


3 2Fe (aq) SCN (aq) FeSCN (aq)

Initially, 50.0mL of 0.10M 3Fe SCN . At equilibrium, the

concentration of 2FeSCN is found to be 0.050M. Calculate the eqK for the reaction. (4

marks)

10. Methanol, 3CH OH, is produced industrially by the following reaction...

2 3CO(g) 2H (g) CH OH(g) heat

A. State two different methods of shifting the equilibrium to the right. (1 mark)

B. In terms of rates, explain why these methods cause the equilibrium to shift to the right. (1 mark)



2 2H (g) I (g) 2HI(g)

A 2.0L container is filled with 0.070 mol of 2H and 0.060 mol of 2I . Equilibrium is reached after

15.0 minutes at which time there is 0.060 mol of HI present. Sketch and label the graphs for

the changes in concentrations of 2H , 2I and HI for the time period of 0 to 30.0 minutes. (3

marks)


12. Consider the observations for the following equilibrium...

2 4 2N O (g) 2NO (g)

colourless brown

A. Sketch the potential energy curve on the graph below for this equilibrium. (1 mark)

B. Explain the colour change using Le Chatelier’s Principle. (1 mark)

C. Other than changing temperature, what could be done to cause a shift to the left? (1 mark)


13. Consider the data obtained for the following equilibrium...


A. Calculate the 2FeSCN in experiment #2. (3 marks)



yellow colourless red

When a few drops of 6.0 M NaOH is added to 25.0 mL of the above system, a precipitate of

3

Fe OH forms and the solution turns pale yellow.

A. Explain this colour change in terms of Le Chatelier’s Principle. (2 marks)

B. Describe the effect on the rate of the reverse reaction as the color change occurs. (1 mark)


2 2 2 4 23I (g) 3F (g) 2IF (g) I F (g)

Initially, 12.00x10 mol of 2I and 13.00x10 mol of 2F and put into a 10.00L flask. At

equilibrium, 4 2I F is 32.00x10 M . Calculate the eqK . (4 marks)


16. Consider the following equilibrium system:

2 2 4 eq2COF (g) CO (g) CF (g), K 2.00

A 2.00 L container is filled with 0.500 mol of 2COF . Calculate the 2COF at equilibrium. (5

marks)


2 2-

4Cu (aq) 4Br (aq) CuBr (aq)

blue colourless green

Cooling the equilibrium changes the colour from green to blue. What effect will the decrease

in temperature have on eqK ? Explain, using Le Chatelier’s Principle. (2 marks)

18. A flask is initially filled with some HI. At equilibrium, the HI 0.80mol/L . What is the

2H at equilibrium? (3 marks)

2 2 eq2HI(g) H (g) I (g), K 0.25


5

2 eq2NOCl(g) 2NO(g) Cl (g),K 1.6x10

A 1.00 L flask is filled with 0.20 mol NOCl , 0.10 mol NO and 0.10 mol 2Cl . State and show

by calculation the direction in which the reaction proceeds to reach equilibrium. (4 marks)


20. Write four statements that apply to all chemical equilibrium systems. (2 marks)


2 2 eqH (g) Br (g) 2HBr(g), K 14.8

A closed container was initially filled with equal moles of 2H and 2Br . When equilibrium is

reached, the HBr is 0.329 mol/L. What was the initial 2H ? (4 marks)

22. Consider the following graph for the reaction…

2 2H (g) I (g) 2HI(g)

A. The temperature is increased at 1t and equilibrium is re-established at 2t . On the above

graph, sketch the line representing the HI between time 1t and 3t . (1 mark)

b. Calculate the value of eqK after 2t . (2 marks)



2 2 32SO (g) O (g) 2SO (g)

A 1.00 L container is initially filled with 0.100 mol 2SO , 0.100 mol 2O . At equilibrium the 2O

concentration is 0.060 mol/L. Calculate the value of eqK . (4 marks)


2 2 22NF (g) N F (g)

Equilibrium shifts to the right when the volume is decreased. Describe the changes in reaction rates that cause this shift to the right. (2 marks)


Initially, 0.200 mol of 2H and o.200 mol of 2I are added to an empty 2.00 L container. At

equilibrium, the 2I is 0.020 mol/L . What is the value of eqK ? (4 marks)

26. State Le Chatelier’s Principle. (2 marks)


4 2 2CH (g)+H O(g) CO(g)+3H (g)

Initially, 0.060 mol 2H O , 0.280 mol CO and 0.740 mol 2H are placed into a 4.00 L container.

At equilibrium, the 2H is 0.200 mol/L . What is the value of eqK ? (4 marks)


28. Given the reacting system...

2 2 eqH (g)+I (g) 2HI(g), K =64

Equal moles of 2H , 2I and HI are placed in a 1.0 L container. Use calculations to determine

the direction the reaction will proceed in order to reach equilibrium. (3 marks)


2 2H (g)+I (g) 2HI(g)

The system is said to shift right as a result of the addition of extra 2H (g) . Describe the

sequence of changes in both forward and reverse reaction rates as the system goes from the original equilibrium to the new equilibrium. (3 marks)


2 eq2NO(g)+Cl (g) 2NOCl(g), K =8.5

A closed flask is found to contain 0.40 M NO(g) , 0.32 M 2Cl (g) and 5.6 M NOCl(g) . Use

appropriate calculations to determine the direction the reaction proceeds to reach equilibrium. (3 marks)


Multiple Choice Question Answer Key

1 D 21 B 41 C 61 C 81 C

2 C 22 C 42 C 62 B 82 B

3 B 23 B 43 B 63 A 83 A

4 A 24 D 44 A 64 D 84 B

5 A 25 C 45 B 65 D 85 A

6 C 26 A 46 B 66 A 86 C

7 A 27 C 47 A 67 D 87 A

8 B 28 A 48 C 68 A 88 A

9 A 29 B 49 A 69 C 89 C

10 A 30 D 50 D 70 C 90 C

11 C 31 B 51 B 71 B 91 D

12 A 32 A 52 C 72 A 92 B

13 C 33 D 53 A 73 A 93 D

14 B 34 A 54 A 74 A 94 A

15 B 35 A 55 C 75 C 95 C

16 D 36 A 56 A 76 A 96 D

17 C 37 D 57 C 77 D 97 D

18 B 38 C 58 C 78 B 98 C

19 D 39 A 59 B 79 D 99 D

20 C 40 C 60 D 80 C 100 D


Written Question Answer Key 1.

2.


3.

4.

5. Consider


6.

7.


8. Consider


9.

10.


11. Consider


12.


13.

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15.

16.


17.

18.

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20.

21.


22.

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24.

25.

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Documents

R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02 ... · R. Janssen, MSEC Chemistry 12 Provincial Workbook (Unit 02), P. 4 / 63 9. Consider the following equilibrium… PCl