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Equilibrium

Notes Worksheets Quiz

1. Approaching Equilibrium WS 1 Q12. LeChatelier's Principle-1 WS 23. LeChatelier's Principle-2 WS 3 Q24. LeChatelier's-3 & Start Lab WS 4 and 55. Lab Lechatelier's Questions 1-10 Conclusion6. Haber/Graphing WS 6 & 7 Q37. Equilibrium Constants WS 8 Q48. Keq Calculations WS 9 & 109. K-trial & Size Keq WS 11 Q510. Entropy & Enthalpy WS 12 Q611. Review Web Review Practice Test 112. Review Practice Test 2 Quizmebc

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Worksheet #1 Approaching Equilibrium

1. What are the conditions necessary for equilibrium?

2. What is a forward reaction versus a reverse reaction?

3. Why does the forward reaction rate decrease as equilibrium is approached?

4. What are the characteristics of equilibrium?

5. Define equilibrium.

6. Define the word dynamic and explain its relevance to the concept of equilibrium.

7. Why does the reverse reaction rate increase as equilibrium is approached?

As a reaction is approaching equilibrium describe how the following change. Explain what causes each change.

8. Reactant concentration.

9. Products concentration.

10. Forward reaction rate.

11. Reverse reaction rate.

12. What is equal at equilibrium?

13. What is constant at equilibrium?

14. Sketch each graph to show how concentrations change as equilibrium is approached

15. Label each graph with the correct description.

The forward and reverse rates as equilibrium is approached

The overall rate as equilibrium is approached

The reactant and product concentrations as equilibrium is approached (two graphs)

[Reactant] [Product] Overall Rate

Worksheet #2 LeChatelier’s Principle Describe the changes that occur after each stress is applied to the equilibrium.

N2 (g) + 3H2 (g) ⇄ 2NH3(g) + 92 KJ

Shifts Shifts to theStress [N2] [H2] [NH3] Right or Left Reactants or Product 1. [N2] is increased 2. [H2] is increased 3. [NH3] is increased 4. Temp is increased 5. [N2] is decreased 6. [H2] is decreased 7. [NH3] is decreased 8. Temp is decreased 9. A catalyst is added

N2O4 (g) ⇄ 2NO2(g) DH = + 92 KJ

Shifts Shifts to Favour the Stress [N2O4] [NO2] Right or Left Reactants or Products 1. [N2O4] is increased 2. [NO2] is increased 3. Temp is increased 4. [N2O4] is decreased 5. [H2] is decreased 6. [NO2] is decreased 7. Temp is decreased 4HCl (g) + O2 (g) ⇄ 2H2O(g) + 2Cl2 (g) + 98 KJ

Shifts Shifts to Favour the Stress [O2] [H2O] [HCl] Right or Left Reactants or Products 1. [HCl] is increased 2. [H2O] is increased 3. [O2] is increased 4. Temp is increased 5. [H2O] is decreased 6. [HCl ] is decreased 7. [O2] is decreased

8. Temp is decreased 9. A catalyst is added

CaCO3 (s) + 170 KJ ⇄ CaO (s) + CO2 (g)

Note : Adding solids or liquids and removing solids or liquids does not shift the equilibrium. This is because you cannot change the concentration of a pure liquid or solid as they are 100% pure. It is only a concentration change that will change the # of collisions and hence shift the equilibrium.

Shifts Shifts to Favor theStress [CO2] Right or Left Reactants or Products 1. CaCO3 is added 2. CaO is added 3. CO2 is added 4. Temp is decreased 5. A catalyst is added 6. [CO2] is decreased 7. Temp is increased

8. CaO is removed

Worksheet #3 Applying Le Châtelier's Principle The oxidation of ammonia is a reversible exothermic reaction that proceeds as follows:

4 NH3 (g) + 5 O2 (g) ⇄ 4 NO (g) + 6 H2O (g)

For each situation described in the table, indicate an increase or decrease in overall concentration from before to after a new equilibrium has been established. Component Stress Equilibrium Concentrations NH3] [O2] [NO] [H2O] NH3 addition

removal O2 addition removal NO addition

removal H2O addition removal

4 NH3 (g) + 5 O2 (g) ⇄ 4 NO (g) + 6 H2O (g)

[NH3] [O2] [NO] [H2O]

Increase in temperature

Decrease in temperature

Increase in pressure

Decrease in pressure

Addition of a catalyst

An Inert gas is added

State the direction in which each of the following equilibrium systems would be shifted upon the application of the following stress listed beside the equation.

1. 2 SO2 (g) + O2 (g) ⇄ 2 SO3 (g) + energy decrease temperature 2. C (s) + CO2 (g) + energy ⇄ 2 CO (g) increase temperature 3. N2O4 (g) ⇄ 2 NO2 (g) increase total pressure 4. CO (g) + H2O (g) ⇄ CO2 (g) + H2 (g) decrease total pressure 5. 2 NOBr (g) ⇄ 2 NO (g) + Br2 (g) decrease total pressure 6. 3 Fe (s) + 4 H2O (g) ⇄ Fe3O4 (s) + 4 H2 (g) add Fe(s)

7. 2 SO2 (g) + O2 (g) ⇄ 2 SO3 (g) add catalyst 8. CaCO3 (s) ⇄ CaO (s) + CO2 (g) remove CO2 (g)

9. N2 (g) + 3 H2 (g) ⇄ 2 NH3 (g) He is added

Consider the following equilibrium system: 3 H2 (g) + N2 (g) ⇄ 2 NH3 (g) + Heat. State what affect each of the following will have on this system:

10. More N2 is added to the system

11. Some NH3 is removed from the system

12. The temperature is increased

13. The volume of the vessel is increased

14. A catalyst was added 15. An inert gas was added at constant

If a catalyst was added to the above reaction and a new equilibrium was established. Compare to the original system, the rates of the forward and reverse reactions of the new equilibrium.

Forward Rate has Reverse Rate has

16. If the temperature was increased in the above reaction and a new equilibrium was established. Compare to the original system, the rates of the forward and reverse reactions of the new equilibrium.

Forward Rate has Reverse Rate has

17. If the volume of the container was increased in the above reaction and a new equilibriumwas established. Compare to the original system, the rates of the forward and reverse reactions of the new equilibrium.

Forward Rate has Reverse Rate has .

Consider the following equilibrium system

H2 (g) + I2 (g) ⇄ 2 HI (g)

State what affect each of the following will have on this system in terms of shifting.

18. The volume of the vessel is increased

19. The pressure is increased

20. A catalyst is added Consider the following equilibrium system: 3 Fe (s) + 4 H2O (g) ⇄ Fe3O4 (s) + 4 H2 (g)

State what affect each of the following will have on this system in terms of shifting.

21. The volume of the vessel is decreased 22. The pressure is decreased 23. More Fe is added to the system 24. Some Fe3O4 is removed from the system 25. A catalyst is added to the system Consider the following equilibrium:

2NO (g) + Br2 (g) + energy ⇄ 2NOBr (g)

State what affect each of the following will have on this system in terms of shifting.26. The volume of the vessel is increased 27. The pressure is decreased 28. More Br2 is added to the system 29. Some NO is removed from the system 30. A catalyst is added to the system

Worksheet #4 Le Chatelier’s Principle

Some CO was added to the system and a new equilibrium was established.

2CO (g) + O2 (g) ⇄ 2CO2 (g) + energy

1. Compared to the original system, the rates of the forward and reverse reactions of the

new equilibrium. Forward Rate has Reverse Rate has

2. Compared to the original concentrations, after the shift, have the new concentrations

increased or decreased?[CO] [O2] [CO2]

3. Did the equilibrium shift favour the formation of reactants or products?

A catalyst was added to the system at constant volume and a new equilibrium was

established. 2CO (g) + O2 (g) ⇄ 2CO2 (g) + energy

4. Compared to the original system, the rates of the forward and reverse reactions of the

new equilibrium. Forward Rate has Reverse Rate has


increased or decreased?

[CO] [O2] [CO2]

6. Did the equilibrium shift favour the formation of reactants or products?

The volume of the container was decreased and a new equilibrium was established.

2CO (g) + O2 (g) ⇄ 2CO2 (g) + energy

7. Compare to the original system, the rates of the forward and reverse reactions of the new

equilibrium. Forward Rate has Reverse Rate has


increased or decreased?

[CO] [O2] [CO2]

9. Did the equilibrium shift favor the formation of reactants or products?

Worksheet #5 Applying Le Châtelier's Principle 1. The chromate and dichromate ions set up an equilibrium system as follows: energy + 2 CrO4

2-(aq) + 2 H+

(aq) ⇄ Cr2O7 2-

(aq) + H2O (l)

yellow orange Describe how the above equilibrium will shift after each stress below:

shift color changeIncrease in [H+] Increase in [CrO4

2-] Increase in [Cr2O7

2-] Decrease in [H+]

Decrease in [CrO4 2-]

Increase in temperature Decrease in temperature Add HCl (aq) Add NaOH

2. The copper (II) ion and copper (II) hydroxide complex exist in equilibrium as follows: Cu(OH)2 (aq) + 4 H2O (l) ⇄ Cu(H2O)4

2+(aq) + 2 OH-

(aq) + 215 kJ

violet light blue Describe how the above equilibrium will shift after each stress below:

shift color changeIncrease in [Cu(H2O)4

2+] Add NaOH Increase in [Cu(OH)2] Decrease in [Cu(H2O)4

2+] Decrease in [Cu(OH)2]

Increase temperature Decrease temperature Add KCl (aq) Add HCl (aq)

3. Consider the equilibrium that follows: 4 HCl (g) + 2 O2 (g) ⇄ 2 H2O (l) + 2 Cl2 (g) + 98 kJ

(clear) (yellow)

Describe how the above equilibrium will shift after each stress below:

shift color changeIncrease in temperature Increase [HCl] Decrease in [Cl2] Decrease temperature Add Ne at constant volume

4. Consider the equilibrium that follows: Cu+ (aq) + Cl-

(aq) ⇄ CuCl (s) ΔH = + 98 kJ (green)

Describe how the above equilibrium will shift after each stress below:Cu+ is green

shift color changeIncrease in temperature Increase [HCl] Add NaCl Decrease temperature Add NaOH (aq)

(check your solubility table for a possible reaction)

Add CuCl(s) Add AgNO3 (aq)

(check your solubility table for a possible reaction)

Add CuNO3 (aq) Add Cu(NO3)2 (aq)

Worksheet #6 Graphing and LeChatelier’s Principle

Consider the following equilibrium system.

I2(g) + Cl2(g) ⇄ 2 ICl (g) + energy

Label the graph that best represents each of the following stresses and shift.

adding I2(g)

increasing the temperature

increasing the volume

removing Cl2(g)

ICl

I2

ICl

I2

ICl

I2 I2

Cl2

Worksheet #7 Maximizing Yield

1. N2O4(g) + 59 KJ ⇄ 2 NO2(g)

Describe four ways of increasing the yield of for the reaction above.

Describe three ways to increase the rate of the above reaction.

2. 2SO3(g) ⇄ 2SO2(g) + O2(g) + 215 KJ

Describe four ways of increasing the yield of for the reaction above.

Describe three ways to increase the rate of the above reaction.

3. H2O(g) ⇄ H2O(l) DH = -150 KJ

Describe three ways of increasing the yield of for the reaction above.

Describe four ways to increase the rate of the above reaction.

4. In the Haber reaction: 3H2(g) + N2(g) ⇌ 2NH3(g) + energy

Explain why each condition is used in the process to make ammonia.

A High pressure of 50 MP

The presence of Ur or Os

Condensing NH3 to a liquid

A relatively high temperature 500 oC Worksheet #8 Equilibrium Calculations 1. SO3(g) + H2O(g) ⇄ H2SO4(l)

At equilibrium [SO3] = 0.400M [H2O] = 0.480M [H2SO4] = 0.600M

Calculate the value of the equilibrium constant. 2. At equilibrium at 100oC, a 2.0L flask contains:

0.075 mol of PCl5 0.050 mol of H2O 0.750 mol of HCl 0.500 mol of POCl3

Calculate the Keq for the reaction: PCl5 (s) + H2O (g) ⇄ 2HCl (g) + POCl3 (g)

3. Keq= 798 at 25oC for the reaction: 2SO2 (g) + O2 (g) ⇄ 2SO3 (g).

In a particular mixture at equilibrium, [SO2]= 4.20 M and [SO3]=11.0M. Calculate the equilibrium [O2] in this mixture at 25oC.

4. Consider the following equilibrium:

2SO2 (g) + O2 (g) ⇄ 2SO3 (g)0.600 moles of SO2 and 0.600 moles of O2 are present in a 4.00 L flask at equilibrium at 100oC. If the Keq = 680.0, calculate the SO3 concentration at 100oC.

5. Consider the following equilibrium: 2 NO2(g) ⇄ N2O4(g)

2.00 moles of NO2 and1.60 moles of N2O4 are present in a 4.00 L flask at equilibrium at 20oC. Calculate the Keq at 20oC.

6. 2 SO3(g) ⇄ 2 SO2(g) + O2(g)

4.00 moles of SO2 and 5.00 moles O2 are present in a 2.00 L container at 100oC and are at equilibrium. Calculate the equilibrium concentration of SO3 and the number of moles SO3

present if the Keq = 1.47 x 10-3.

7. If at equilibrium [H2] = 0.200M and [I2] = 0.200M and Keq=55.6 at 250oC, calculate the

equilibrium concentration of HI.H2 (g) + I2 (g) ⇄ 2HI (g)

8. 1.60 moles CO, 1.60 moles H2O, 4.00 moles CO2, 4.00 moles H2 are found in an 8.00 L

container at 690oC at equilibrium. CO (g) + H2O (g) ⇄ CO2 (g) + H2 (g)Calculate the value of the equilibrium constant.

Worksheet #9 Equilibrium Calculations

Solve each problem and show all of your work. 1. At equilibrium, a 5.0L flask contains:


Calculate the Keq for the reaction: PCl5 (s) + H2O (g) ⇄ 2HCl (g) + POCl3 (g)

2. Keq= 798 for the reaction: 2SO2 (g) + O2 (g) ⇄ 2SO3 (g).

In a particular mixture at equilibrium, [SO2]= 4.20 M and [SO3]=11.0 M. Calculate the equilibrium [O2] in this mixture.

3. Consider the following equilibrium: 2SO2 (g) + O2 (g) ⇄ 2SO3 (g)

When 0.600 moles of SO2 and 0.600 moles of O2 are placed into a 1.00 litre container and allowed to reach equilibrium, the equilibrium [SO3] is to be 0.250 M. Calculate the Keq value.

4. Consider the following equilibrium: 2 NO2(g) ⇄ N2O4(g)

2.00 moles of NO2 are placed in a 1.00 L flask and allowed to react. At equilibrium 1.80 moles NO2 are present. Calculate the Keq.

5. 2 SO2(g) + O2(g) ⇄ 2 SO3(g)

4.00 moles of SO2 and 5.00 moles O2 are placed in a 2.00 L container at 200oC and allowed to reach equilibrium. If the equilibrium concentration of O2 is 2.00 M, calculate the Keq

6. If the initial [H2] = 0.200 M, [I2] = 0.200 M and Keq = 55.6 at 250oC calculate the

equilibrium concentrations of all molecules.H2 (g) + I2 (g) ⇄ 2HI (g)

7. 1.60 moles CO and 1.60 moles H2O are placed in a 2.00 L container at 690 oC

(Keq = 10.0). CO (g) + H2O (g) ⇄ CO2 (g) + H2 (g)Calculate all equilibrium concentrations.

8. SO3(g) + NO(g) ⇄ NO2(g) + SO2(g)

Keq = 0.800 at 100oC. If 4.00 moles of each reactant are placed in a 2.00L container, calculate all equilibrium concentrations at 100oC.

9. Consider the following equilibrium system: 2NO2(g) ⇌ N2O4

Two sets of equilibrium data are listed for the same temperature. Container 1 2.00 L 0.12 moles NO2 0.16 moles N2O4

Container 2 5.00 L 0.26 moles NO2 ? moles N2O4

Determine the number of moles N2O4 in the second container. Get a Keq from the first container and use it for the second container.

Worksheet #10 Equilibrium Calculations Solve each problem and show all of your work. 1. At equilibrium, a 2.0 L flask contains:


Calculate the Keq for the reaction: PCl5 (g) + H2O (g) ⇄ 2HCl (g) + POCl3 (g)

2. Keq= 798 for the reaction: 2SO2 (g) + O2 (g) ⇄ 2SO3 (g).In a particular mixture at equilibrium, [SO2] = 4.20 M and [SO3] = 11.0M. Calculate the equilibrium [O2] in this mixture.

3. Consider the following equilibrium: 2SO2 (g) + O2 (g) ⇄ 2SO3 (g)

When a 0.600 moles of SO2 and 0.600 moles of O2 are placed into a 2.00 litre container and allowed to reach equilibrium, the equilibrium [SO3] is to be 0.250 M. Calculate the Keq value.

4. H2(g) + S(s) ⇄ H2S(g) Keq= 140.60 moles of H2 and 1.4 moles of S are placed into a 2.0L flask and allowed to reach equilibrium. Calculate the [H2] at equilibrium.

5. Keq = 0.0183 for the reaction: 2HI(g) ⇄ H2(g) + I2(g)

If 3.0 moles of HI are placed in a 5.00L vessel and allowed to reach equilibrium, what is the equilibrium concentration of H2?

6. Consider the equilibrium: I2 (g) + Cl2 (g) ⇄ 2ICl (g) Keq= 10.0

The same number of moles of I2 and Cl2 are placed in a 1.0L flask and allowed to reach equilibrium. If the equilibrium concentration of ICl is 0.040 M, calculate the initial number of moles of I2 and Cl2.

7. Consider the equilibrium: 2ICl(g) ⇄ I2 (g) + Cl2 (g) Keq= 10.0

If x moles of ICl were placed in a 5.0 L container at 10 oC and if an equilibrium concentration of I2 was found to be 0.60 M, calculate the number of moles ICl initially present.

8. A student places 2.00 moles SO3 in a 1.00 L flask. At equilibrium [O2] = 0.10 M at

130 oC. Calculate the Keq. 2SO2(g) + O2(g) ⇄ 2SO3(g)

Worksheet #11 Review, Ktrial, & Size of Keq 1. 2 CrO4

-2 (aq) + 2H+ (aq) ⇄ Cr2O7-2 (aq) + H2O (l)

Calculate the Keq if the following amounts were found at equilibrium in a 2.0L volume.CrO4

-2 = .030 mol, H+ = .020 mol, Cr2O7-2 = 0.32 mol, H2O = 110 mol

2. PCl5(s) + H2O(g) ⇄ 2HCl (g) + POCl3 (g) Keq= 11

At equilibrium the 4.0L flask contains the indicated amounts of the three chemicals. PCl5 0.012 mol H2O 0.016 mol HCl 0.120 molCalculate [POCl3].

3. 6.0 moles H2S are placed in a 2.0 L container. At equilibrium 5.0 moles H2 are present.

Calculate the Keq 2H2S(g) ⇄ 2H2(g) + S2(g)

4. 4.0 moles H2 and 2.0 moles Br2 are placed in a 1.0L container at 180oC. If the

[HBr] = 3.0 M at equilibrium, calculate the Keq.H2(g) + Br2(g) ⇄ 2HBr(g)

5. At 2000 0C Keq = 11.6 for: 2NO(g) ⇄ N2(g) + O2(g). If some NO was placed in a

2.0 L vessel, and the equilibrium [N2] = 0.120 M, calculate all other equilibrium concentrations.

6. At 800oC, Keq= 0.279 for CO2(g) + H2(g) ⇄ CO(g) + H2O(g).

If 2.00 moles CO( g) and 2.00 moles H2O (g) are placed in a 500.0 mL container, calculate all equilibrium concentrations.

7. CO(g) + H2O(g) ⇄ CO2(g) + H2(g) Keq= 10.0 at 690oC. If at a certain time

[CO] = 0.80 M, [H2O] = 0.050 M, [CO2] = 0.50 M and [H2] = 0.40 M, is the reaction at equilibrium? If not, how will it shift in order to get to equilibrium

8. For the reaction: CO(g) + H2O(g) ⇄ CO2(g) + H2(g) Keq= 10.0 at 690 oC. The following

concentrations were observed: [CO]=2.0 M, [H2]= 1.0 M, [CO2]=2.0 M, [H2O] = 0.10 M. Is the reaction at equilibrium? If not, how will it shift in order to get to equilibrium?

9. For the equation below, the following concentrations were observed: [CO] = 1.5 M,

[H2] = 1.2 M, [CO2] = 1.0 M, [H2O] = 0.10 M. Is the reaction at equilibrium? If not, how will it shift in order to get to equilibrium? CO (g) + H2O (g) ⇄ CO2 (g) + H2 (g) Keq= 10.0 at 690oC

10. At a certain temperature the Keq for a reaction is 75. 2O3(g) ⇄ 3O2(g)

Predict the direction in which the equilibrium will proceed, if any, when the following amounts are introduced to a 10 L vessel. a) 0.60 mole of O3 and 3.0 mol of O2

b) 0.050 mole of O3 and 7.0 mol of O2

c) 1.5 mole of O3 and no O2

11) Consider the following equilibrium:

a) 2NO2 (g) ⇄ N2O4 (g) Keq = 2.2b) Cu2+

(aq) + 2Ag(s) ⇄ Cu(s) + 2Ag+ (aq) Keq = 1 x 10-15

c) Pb2+ (aq) + 2 Cl- (aq) ⇄ PbCl2(s) Keq = 6.3 x 104

d) SO2(g) + O2 (g) ⇄ SO3 (g) Keq = 110

i) Which equilibrium favors products to the greatest extent? ______ii) Which equilibrium favors reactants to the greatest extent? ______

12. What is the only way to change the value of the Keq? 13. In the reaction: A + B ⇄ C + D + 100 kJ, what happens to the value of Keq if we increase

the temperature? 14. If the value of Keq decreases when we decrease the temperature, is the reaction

exothermic or endothermic? 15. In the reaction; W + X + 100kJ ⇄ Y + Z, what happens to the value of Keq if we increase

the (X)? Explain your answer. 16. If the value of Keq increases when we decrease the temperature, is the reaction

exothermic or endothermic? 17. Predict whether reactants of products are favored in the following equilibrium systems

(a) CH3COOH(aq) ⇄ H+(aq) + CH3COO-

(aq) Keq = 1.8 x 10-5

(b) H2O2(aq) ⇄ H+(aq) + HO2(aq) Keq = 2.6 x 10-12

(c) CuSO4(aq) (+ Zn(s) ⇄ Cu(s) + ZnSO4(aq) Keq = 1037

18. What effect will each of the following have on the Keq of the reaction shown below?

2NO2(g) + heat ⇄ N2O4(g) Keq = 2.2

(a) adding a catalyst (b) increasing the concentration of a reactant (c) increasing the concentration of a product (d) decreasing the volume (e) decreasing the pressure (f) increasing the temperature (g) decreasing the temperature

Worksheet #12 Enthalpy & Entropy

For each of these processes, predict if Entropy increases or decreases. 1. 2H2(g) + O2(g) ⇄ 2H2O(g) 2. 2SO3(g) ⇄ 2SO2(g) + O2(g) 3. Ag+

(aq) + Cl-(aq) ⇄ AgCl(s)

4. Cl2(g) ⇄ 2Cl(g) 5. H2O(l) ⇄ H2O(g)

6. CaCO3(s) + 180 kJ ⇄ CaO(s) + CO2(g) 7. I2(s) + 608 kJ ⇄ I2(aq)

8. 4Fe(s) + 3O2(g) ⇄ 2Fe2O3(s) + 1570 kJ

Consider both Enthalpy and Entropy and determine if each reaction will

a) go to completionb) not occur orc) go to equilibrium

9. H2O(l) ⇄ H2O(g) DH = 150 kJ 10. CaCO3(s) + 180 kJ ⇄ CaO(s) + CO2(g) 11. I2(s) ⇄ I2(aq) + 608 kJ 12. 4Fe(s) + 3O2(g) ⇄ 2Fe2O3(s) ∆H = +1570 kJ 13. Cl2(g) ⇄ 2Cl(g) DH = +26.8 kJ 14. Ag+

(aq) + Cl-(aq) ⇄ AgCl(s) + 86.2 kJ

Consider both Enthalpy and Entropy and determine if each reaction will

a) have a large Keqb) have a small Keqc) have a Keq about equal to 1

15. H2SO4(aq) + Zn(s) ⇄ ZnSO4(aq) + H2(g) DH = +207 kJ

16. NH4NO3(s) ⇄ NH4+

(aq) + NO3-(aq) DH = -30 kJ

17. N2(g) + 3H2(g) + 92 kJ ⇄ 2NH3(g)

18. H2O(l) + 150 kJ ⇄ H2O(g)

19. Ca(s) + H2O(l) ⇄ Ca(OH)2(aq) + H2(g) DH = +210 kJ Equilibrium Quiz # 1 Approaching Equilibrium

1. Consider the following equilibrium: H2O(g) + CO(g) ⇄ H2(g) + CO2(g)

A closed container is initially filled with H2O and CO. As the reaction proceeds towards equilibrium the A. [CO] and [CO2] both increase B. [ CO] and [CO2] both decrease C. [CO] increases and [CO2] decreases D. [CO] decreases and [CO2] increases 2. Consider the following equilibrium: 2SO3(g) ⇄ 2SO2(g) + O2(g)

At equilibrium, the rate of decomposition of SO3

A. Equals the rate of formation of O2

B. Equals the rate of formation of SO3

C. Is less than the rate of formation of O2

D. Is less than the rate of formation of SO3

3. Which of the following is true for all equilibrium systems? A. The mass of reactants is equal to the mass of products B. Addition of a catalyst changes the equilibrium concentrations C. The concentration of reactants is equal to the concentration of products D. The rate of the forward reaction is equal to the rate of the reverse reaction 4. Consider the following: 2NH3(g) ⇄ N2(g) + 3H2(g)

A flask is initially filled with NH3. As the system approaches equilibrium, the rate of the forward reaction A. Increases as the rate of the reverse reaction decreases B. Decreases as the rate of the reverse reaction increases C. Increases as the rate of the reverse reaction increases D. Decreases as the rate of the reverse reaction decreases 5. A system at equilibrium is said to be dynamic because at equilibrium the A. Temperature does not change B. Macroscopic properties are constant

C. Forward and reverse reactions continue to occur D. Concentrations of reactants and products are constant 6. In all systems at equilibrium, the A. Concentration of reactants is less than the concentration of products B. Concentration of reactants and the concentration of products are equal C. Concentration of reactants is greater than the concentration of products D. Concentration of reactants and the concentration of products are constant


At high temperature, H2O and CO are placed in a closed container. As the system approaches equilibrium, the

A. Rate of the forward and reverse reaction both increase B. Rate of the forward and reverse reaction both decrease

C. Rate of the forward reaction decreases and the rate of the reverse reaction increasesD. Rate of the forward reaction increases and the rate of the reverse reaction decreases

8. Which of the following statements are true for all equilibrium systems?I. Macroscopic Properties are constantII. Mass of the reactants equals mass of the productsIII Equilibrium can be achieved from either products or reactants

A. I and II only B. I and III only C. II and III only D. I, II, and III 9. Consider the following equilibrium: N2O4(g) + heat ⇄ 2NO2(g)

Initially, a 1.0 L container is filled with 2.0 mol of NO2. As the system approaches equilibrium, the rate of reaction of NO2

A. Increases and [ N2O4 ] increases B. Increases and [ N2O4 ] decreases C. Decreases and [ N2O4 ] increases D. Decreases and [ N2O4 ] decreases 10. Consider the following equilibrium: N2(g) + O2(g) ⇄ 2NO(g)

Nitrogen gas and oxygen react when placed in a closed container. As the reaction proceeds towards equilibrium, the rate of the reverse reaction

A. Increases as the concentration of products decreases B. Decreases as the concentration of products decreases C. Increases as the concentration of products increases D. Decreases as the concentration of products increases

11. Consider the following

I Constant TemperatureII Equal concentrations of reactants and productsIII Equal rates of forward and reverse reactions

A system at equilibrium must have

A. I and II only B. I and III only C. II and III only D. I, II , and III 12. Consider the following: N2O4(g) ⇌ 2NO2(g)

Colourless BrownNO2 is placed in a flask at a constant temperature. Which of the following is true as the system approaches equilibrium?A. The colour gets darker as [NO2] increases.B. The colour gets lighter as [NO2] decreases.C. The colour gets darker as [N2O4] increases.D. The colour gets lighter as [N2O4] decreases.

13. Consider the following: N2O4(g) ⇌ 2NO2(g)

Colourless Brown

N2O4 is placed in a flask at a constant temperature. Which of the following is true as the system approaches equilibrium?A. The colour gets darker as [NO2] increases.B. The colour gets lighter as [NO2] decreases.C. The colour gets darker as [N2O4] increases.D. The colour gets lighter as [N2O4] decreases.

14. Consider the following equilibrium: PCl3(g) + Cl2(g) ⇌ PCl5(g)

If PCl5 is put in a container, how will the reaction rates change as the system approaches equilibrium? Forward Rate Reverse Rate

A. increases increasesB. increases decreasesC. decreases decreasesD. decreases increases

15. Consider the following equilibrium system: H2O(g) + CO(g) ⇌ CO2(g) + H2(g)

2.00 mole of CO2 and 2.00 mole of H2 are placed in a container and the system approached equilibrium. The following changes occur:

[CO2] [H2] [CO]A. increases decreases decreasesB. increases increases decreasesC. decreases increases increasesD. decreases decreases increases

16. For the equilibrium system below:Zn(s) + CuSO4(aq) ® Cu(s) + ZnSO4(aq)

We would know the system is at equilibrium because:A. [Cu2+] = [Zn2+]B. Cu(s) = Zn(s)

C. the mass of Cu(s) remains constant.D. the mass of the entire system remains constant.

17. Which of the factors below is not a condition necessary for equilibrium? A. a closed systemB. a constant temperatureC. equal forward and reverse reaction ratesD. equal concentrations of reactants and products

18. Products are placed in a beaker. How do the rates of the forward and reverse reactions change as the system proceeds to equilibrium?

Forward Rate Reverse RateA. increases increasesB. increases decreasesC. decreases increasesD. decreases decreases

19. Which of the factors below is not a condition necessary for equilibrium? A. constant macroscopic propertiesB. constant concentrations of reactant and productC. equal forward and reverse reaction ratesD. a high activation energy

Equilibrium Quiz #2 LeChatelier’s Principle

1. Consider the following reaction: 2SO2(g) + O2(g) ⇄ 2SO3(g) ∆H = -197 kJ/molWhich of the following will not shift the equilibrium to the right?

A. Adding more O2

B. Adding a catalyst C. Increasing the pressure D. Lowing the temperature2. Consider the following equilibrium system: CaCO3(s) ⇄ CaO(s) + CO2(g)

Which one of the following changes would cause the above system to shift left? A. Add more CaO B. Remove CaCO3

C. Decrease volume D. Increase surface area of CaO

3. Consider the following equilibrium: SO2Cl2(g) + energy ⇄ SO2(g) + Cl2(g)

When the temperature is decreased, the equilibrium shifts A. Left and [ SO2Cl2 ] increases B. Left and [ SO2Cl2 ] decreases C. Right and [ SO2Cl2 ] increases D. Right and [ SO2Cl2 ] increases

4. Consider the following equilibrium: 2SO3(g) ⇄ 2SO2(g) + O2(g)

The volume of the system is decreased at a constant temperature. A new state of equilibrium is established by a shift of the original equilibrium to the

A. Left and [SO3] increases B. Right and [SO3] decreases C. Left and [SO3] remains unchanged D. Right and [SO3] remains unchanged

5. Consider the following equilibrium system: CO2(g) + H2(g) ⇄ CO(g) + H2O(g)

Which of the following, when added to the system above, would result in a net decrease in [H2O]? A. CO2

B. H2

C. CO D. H2

6. Consider the following equilibrium: C(s) + 2H2(g) ⇄ CH4(g) + 74 kJWhen a small amount of solid C is added to the system

A. [H2] decreases B. [CH4] increases C. The temperature increases

D. All concentrations remain constant

7. Consider the following equilibrium: 2NO(g) + Cl2(g) ⇄ 2NOCl(g)

At constant temperature and volume, Cl2 is added to the above equilibrium system. As equilibrium re-establishes, the

A. [NOCl] will decrease B. The temperature increases C. [NO] will increase D. [NOCl] will increase8. Consider the following equilibrium: Cl2O7(g) +8H2(g) ⇄ 2HCl(g) + 7H2O(g)

Which of the following would increase the number of moles of HCl? A. Increase [H2O] B. Increase [Cl2O7] C. Increase total pressure D. Increase volume of the system

9. Consider the following equilibrium: 2HI(g) ⇄ H2(g) + I2(g) ∆H = -68kJWhich of the following would cause the equilibrium to shift right?

A. Increasing the volume B. Decreasing the volume C. Increasing the temperature D. Decreasing the temperature 10. A 1.00 L flask contains a gaseous equilibrium system. The addition of reactants to this flask results in a A. Shift to the left and decrease in the concentration of products B. Shift to the left and increase in the concentration of products C. Shift to the right and decrease in the concentration of products D. Shift to the right and increase in the concentration of products

11. When the temperature of an equilibrium system is increased, the equilibrium always shifts to favor the A. Exothermic reaction B. Endothermic reaction C. Formation of products D. Formation of reactants

12. An equilibrium system shifts left when the A. Rate of the forward reaction is equal to the rate of the reverse reaction B. Rate of the forward reaction is less than the rate of the reverse reaction C. Rate of the forward reaction is greater than the rate of the reverse reaction A. Rate of the forward reaction and the rate of the reverse reaction are constant

13. Consider the following equilibrium: 2SO2(g) + O2(g) ⇄ 2SO3(g) ∆H = -198 kJThere will be no shift in the equilibrium when

A. More O2 is added B. Catalyst is added C. The volume is increased D. The temperature is increased

14. Consider the following equilibrium: 2NOCl(g) ⇄ 2NO(g) + Cl2(g)

In a 1.0 L container at equilibrium there are 1.0 mol NOCl, 0.70 mol NO and 0.40 mol Cl2. At constant temperature and volume, 0.10 mol NOCl is added. The concentrations in the “new” equilibrium in comparison to the concentrations in the “old” equilibrium are

A.B.C.D.

[NOCl] [NO] [Cl2]new = old new = old new = oldnew > old new > old new > oldnew < old new < old new > old new < old new > old new > old

15. Consider the following equilibrium: N2O4(g) + 58 kJ ⇄ 2NO2(g)

The equilibrium shifts right when A. NO2 is added B. N2O4 is removed C. The temperature is decreased D. The volume of the system is increased

16. Consider the following equilibrium: 2SO2(g) + O2(g) ⇄ 2SO 3(g)

Which of the following will shift the equilibrium to the right?

I. Adding more O2

II. Adding more SO3

III. Adding a catalyst

A. I only B. III only C. I and II only D. II and III only

17. Consider the following equilibrium: energy + 2NaClO3(s) ⇌ 2NaCl(s) + 3O2(g)

Which of the following will cause a shift to the left?A. adding more O2

B. adding more NaClC. removing some NaClO3

D. increasing the temperature

18. Consider the following equilibrium:CO(g) + 2H2(g) ⇌ CH3OH(g) + energyWhich of the factors below would decrease the concentration of CH3OH at equilibrium?A. an addition of COB. an increase in H2

C. a decrease in the temperatureD. an increase in the temperature

19. Consider the following equilibrium: energy + 2NaClO3(s) ⇌ 2NaCl(s) + 3O2(g)

Which of the following will cause a shift to the right?A. adding more O2

B. adding more NaClC. removing some NaCl(s)

D. increasing the temperature

20. Consider the following equilibrium: 2SO2(g) + O2(g) ⇄ 2SO 3(g)

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

I. Removing O2

II. Adding more SO3

III. Adding a catalyst

A. I only B. III only C. I and II only D. II and III only

21. Consider the following equilibrium: N2O4(g) + energy ⇌ 2NO2(g)

How are N2O4 and NO2 affected by the addition of He into the container at constant volume.N2O4 NO2

A. no change no changeB. no change increasesC. increases decreasesD. decreases increases

22. Which of the following stresses will cause a shift to the reactants?H2(g) + Br2(g) ⇌ 2HBr(g) + energyA. increase [Br2]B. increase [H2]C. decrease temperatureD. increase temperature

23. Which of the following stresses will cause a shift to the products?H2(g) + Br2(g) ⇌ 2HBr(g) + energyA. decrease [Br2]B. decrease [H2]C. decrease temperatureD. increase temperature

24. Which of the following two stresses will each cause the system to shift to the left?2SO2(g) + O2(g) ⇄ 2SO 3(g) + energyA. decrease temperature and decrease [O2]B. increase temperature and increase [SO3]C. increase temperature and decrease [SO3]D. decrease temperature and increase [SO2]

25. SrCO3(s) + 215 kJ ⇌ SrO(s) + CO2(g)

Which of the following conditions would produce the greatest yield of SrO(s)?Temperature Pressure

A. low lowB. low highC. high lowD. high high

26. The Haber Process is used to produce ammonia commercially according to the following equilibrium:N2(g) + 3H2(g) ⇌ 2NH3(g) + energyWhich of the following conditions will produce the highest yield of ammonia?

A. increase temperature and increase pressureB. increase temperature and decrease pressureC. decrease temperature and increase pressureD. decrease temperature and decrease pressure

27. Consider the following reaction: 2SO2(g) + O2(g) ⇄ 2SO3(g) ∆H = -197 kJ/molIf the volume is increased what happens to position of the equilibrium?A. shifts to the rightB. shifts to the leftC. no shiftD. shifts in the exothermic direction

28. Consider the following reaction: 2NH3(g) + energy ⇄ N2(g) + 3H2(g)

If the volume is increased what happens to position of the equilibrium?A. shifts to the rightB. shifts to the leftC. no shiftD. shifts in the exothermic direction

29. Consider the following reaction: SrCO3(s) + 215 kJ ⇌ SrO(s) + CO2(g)

If the volume is decreased what happens to position of the equilibrium?A. shifts to the rightB. shifts to the leftC. no shiftD. shifts in the exothermic direction

30. Consider the following reaction: H2(g) + Br2(g) ⇌ 2HBr(g) + energy

If the volume is increased what happens to position of the equilibrium?A. shifts to the rightB. shifts to the leftC. no shiftD. shifts in the exothermic direction

31. Consider the following reaction: N2O4(g) + energy ⇌ 2NO2(g)

If the volume is decreased what happens to position of the equilibrium?A. shifts to the rightB. shifts to the leftC. no shiftD. shifts in the exothermic direction

Quiz # 3 Yield/Graphing/LeChatelier’s Principle

1. When a catalyst is added to an equilibrium system, the forward reaction A. Increases and the reverse decreases B. Decreases and the reverse decreases C. Decreases and the reverse increases D. Increases and the reverse increases

2. Consider the following concentration versus time graph for the equilibriumN2O4(g) ⇄ 2NO2(g)

Concentration

“t” TIME(S)

At time= “t”, which one of the following stresses occurred A. Catalyst was added B. Pressure was changed C. Temperature was changed D. Concentration of NO2 was changed

3. Which of the following reactions will shift left when pressure is increased and when temperature is decreased?

A. N2(g) + 2O2(g) + heat ⇄ 2NO2(g)

B. N2(g) + 3H2(g) ⇄ 2NH3(g) + heat C. CH4(g) + H2O(g) + heat ⇄ CO(g) + 3H2(g)

D. CS2(g) + 4H2(g) ⇄ CH4(g) + 2H2S(g) + heat

4. Consider the following graph, which relates to this equilibrium N2(g) + 3H2(g) ⇄ 2NH3(g) ∆H = -92kJ

Which of the following caused the changes in the concentrations at time t ?

A. Addition of N2

B. Removal of H2

C. Decrease in temperature D. Decrease in reaction volume 5. Consider the following equilibrium: CH4(g) + H2O(g) + heat ⇄ CO(g) + 3H2(g)

In which of the following will both stresses shift the equilibrium right A. A decrease in temperature and a decrease in volume B. An increase in temperature and a decrease in volume C. A decrease in temperature and an increase in volume D. An increase in temperature and an increase in volume

6. Consider the following equilibrium system: N2(g) + 3H2(g) ⇄ 2NH3(g) + 92 kJIn order to maximize the yield for this reaction, the best conditions are:

A. Low pressure and low temperature B. Low pressure and high temperature C. High temperature and low pressure D. High pressure and low temperature

[ ][H2]

[NH3]

Time

[N2]

7. Consider the following equilibrium system: NH3(aq) + H2O(l) ⇄ NH+4(aq) + OH--

(aq)

Which of the following when added to the above equilibrium system would cause an increase in [OH-] A. NH3

B. H2O C. NH4

+

D. HCl

8. Consider the following reversible reaction: Fe3+(aq) + SCN-

(aq) ⇄ FeSCN2+(aq)

A solution of Fe(NO3)3 is added to a solution of KSCN. Which one of the following statements describes the changes in forward and reverse reaction rates as the reaction moves towards equilibrium?A. Forward and reverse rates increase

B. Forward and reverse rates decrease C. Forward rate increases and reverse rate decrease D. Forward rate decreases and reverse rate increase

9. Consider the following equilibrium: N2(g) + O2(g) ⇄ 2NO(g) ∆H= + 181 kJWhen the temperature is decreased, the equilibrium

A. Shifts left and [NO] decreases B. Shifts left and [NO] increases C. Shifts right and [NO] increases D. Shifts right and [NO] decreases

10. Consider the following equilibrium: N2(g) + 3H2(g) ⇄ 2NH3(g) + 92 kJIn which of the following will both changes shift the equilibrium right?

A. An increase in volume and a decrease in temperature B. An increase in volume and a increase in temperature C. A decrease in volume and a decrease in temperature D. A decrease in volume and an increase in temperature

11. Consider the following equilibrium: CaCO3(s) + 556 kJ ⇄ CaCO(s) + CO2(g)

The equilibrium will shift to the right A. CO2 is added B. CaCO3(s) is added C. The temperature is increased D. The temperature is decreased12. Consider the following equilibrium: SO2(g) + NO2(g) ⇄ SO3(g) + NO(g) + energy

The equilibrium does not shift with a change in the A. Volume B. Temperature C. Concentration of products D. Concentration of reactants

13. Consider the following equilibrium: 2Hl(g) ⇄ H2(g) + I2(g)

At constant temperature and volume, more I2 is added to the above equilibrium. A new state of equilibrium results from a shift to the

A. Left with a net decrease in [H2] B. Left with a net increase in [H2] C. Right with a net increase in [H2] D. Right with a net decrease in [H2]

14. Consider the following diagram for the equilibrium system:Energy + N2O4(g) ⇄ 2NO2(g)

A. [NO2] was increased.B. [N2O4] was decreased.C. Temperature was increased.D. Temperature was decreased.


A. [NO2] was increased.B. [N2O4] was decreased.C. Temperature was increased.D. Temperature was decreased.


A. [NO2] was increased.B. [N2O4] was decreased.C. Temperature was increased.D. The Volume was decreased.

Concentration[N2O4]

[NO2]

Concentration[N2O4]

[NO2]

Concentration

[N2O4]

[NO2]

17. Which of the following describes the temperature and pressure needed for the maximum yield of NO2?Energy + N2O4(g) ⇄ 2NO2(g)

Temperature PressureA. low lowB. low highC. high lowD. high high

18. Which of the following describes the temperature and pressure needed for the maximum yield of NH3?N2(g) + 3H2(g) ⇄ 2NH3(g) + 92 kJ


19. Which of the following describes the temperature and pressure needed for the maximum yield of CO2?CaCO3(s) ⇄ CaCO(s) + CO2(g) ΔH = +215 kJ


20. Consider the following equilibrium: CaCO3(s) ⇌ CaO(s) + CO2(g) ΔH = +160 kJWhich starting materials could establish an equilibrium?1 CaCO3(s) 2 CaO(s)

3 CaO(s) and CO2(g) 4 CaCO3(s) and CO2(g)

A. 1, 2, 3 onlyB. 1, 2, 4 onlyC. 1, 3, 4 onlyD. 3, 4 only

Consider the following reaction for the next five questions 21 to 25.

4NH3(g) + 3O2(g) ⇌ 2N2(g) + 6H2O(l) + 1250 kJ

21. Which of the following would cause the concentration of NH3 at equilibrium to increase?A. an increase in [O2]B. a increase in volumeC. a decrease in temperatureD. an increase in temperature

22. What happens when NH3 is added to the above system?Equilibrium [N2]A. no shift unchangedB. shifts right decreasesC. shifts right increasesD. shifts left increases

23. If some O2 is removed from the system, what happens to the forward and reverse reaction rates after equilibrium is re-established?

Forward Reaction Rate Reverse Reaction RateA. increases decreasesB. decreases decreasesC. increases increasesD. decreases increases

24. If some O2 is injected into the system, what happens to the forward and reverse reaction rates during the shift to re-establish equilibrium?

Forward Reaction Rate Reverse Reaction RateA. increases decreasesB. decreases decreasesC. increases increasesD. decreases increases

25. Consider the equilibrium: N2(g) + 3H2(g) ⇄ 2NH3(g) + 92 kJThe following diagram represents the rate of the reverse reaction.

Which of the following stresses explains what happened at t1 ?A. [H2] increased.B. [N2] decreased.C. [NH3] increased.D. [NH3] decreased.

26. Consider the equilibrium: N2(g) + 3H2(g) ⇄ 2NH3(g) + 92 kJThe following diagram represents the rate of the forward reaction.

Which of the following stresses explains what happened at t1 ?A. [H2] increased.B. temperature was loweredC. [NH3] increased.D. [NH3] decreased.

t1

t1

27. Consider the equilibrium: N2(g) + 3H2(g) ⇄ 2NH3(g) + 92 kJThe following diagram represents the rate of the reverse reaction.

Which of the following stresses explains what happened at t1 ?A. [H2] increased.B. [N2] decreased.C. [NH3] increased.D. [NH3] decreased.

28. A small amount of NaOH is added to the following equilibrium system: 2CrO4

2- + 2H+ ⇌ Cr2O72-

(aq) + H2O(l)

How do the [CrO42-] and the reverse reaction rate change as equilibrium is re-established?

[CrO42-] Reverse Rate


29. A small amount of H2SO4 is added to the following equilibrium system: 2CrO4

2- + 2H+ ⇌ Cr2O72-

(aq) + H2O(l)

How do the [CrO42-] and the reverse reaction rate change as equilibrium is re-established?

[CrO42-] Reverse Rate


30. A small amount of NaOH is added to the following equilibrium system: 2CrO4

2- + 2H+ ⇌ Cr2O72-

(aq) + H2O(l)

How do the [Cr2O72-] and the reverse reaction rate change as equilibrium is re-established?

[Cr2O72-] Reverse Rate


31. A small amount of H2SO4 is added to the following equilibrium system: 2CrO4

2- + 2H+ ⇌ Cr2O72-

(aq) + H2O(l)

t1

How do the [Cr2O72-] and the reverse reaction rate change as equilibrium is re-established?

[Cr2O72-] Reverse Rate


Quiz #4 Writing and Calculating Keq

1. The equilibrium constant expression for the following reaction is: 2Hg(l) + O2(g) ⇄ 2HgO(s)

A. Keq = 1/[O2] B. Keq = [O2] C. Keq = [2HgO] / [O2] [2Hg] D. Keq = [HgO]2 / [Hg]2[O2]

2. Identify the equilibrium system that least favors the formation of products A. 2HgO(s) ⇄ 2Hg(l) + O2(g) Keq = 1.2 x 10-22

B. CH3COOH(aq) + H2O(l) ⇄ H3O+(aq) + CH3COO-

(aq) Keq = 1.8 x 10-5

C. 2NO(g) + O2(g) ⇄ 2NO2(g) Keq = 6.5 x 105

D. H2(g) + Cl2(g) ⇄ 2HCl(g) Keq = 1.8 x 1033

3. Consider the following equilibrium system: 3O2(g) ⇄ 2O3(g) Keq = 1Which equation compares the concentration of oxygen and ozone?

A. [O2] = [O3]2/3

B. [O2] = [O3] C. [O2] = [O3]3/2

D. [O2] 2/5 = [O3]

4. For which of the following equilibrium does Keq = [O2] A. O2(l) ⇄ O2(g)

B. 2O3(g) ⇄ 3O2(g)

C. 2H2O(l) ⇄ 2H2(g) + O2(g)

D. 2Hg(s) + O2(g) ⇄ 2HgO(s)

5. Consider the following equilibrium system at 25O C : 2SO2(g) + O2(g) ⇄ 2SO3(g)

At equilibrium, [SO2] is 4.00 x 10-3 mol/L, [O2] = 4.00 x 10-3 mol/L and [SO3] is 2.33 x 10-3 mol/L. From this data, the Keq value for the above system is

A. 6.85 x 10-3

B. 1.18 x 10-2

C. 84.8 D. 146

6. Consider the following equilibrium system: PCl5(g) ⇄ PCl3(g) + Cl2(g)

At equilibrium, [PCl5] is a 0.400 M. [PCl3] is 1.50 M and [Cl2] is 0.600 M. The Keq for the reaction is

A. 0.360 B. 0.444

C. 0.900 D. 2.257. Consider the following equilibrium: 2H2S(g) ⇄ 2H2(g) + S2(g)

At equilibrium, [H2S] = 0.50 mol/L. [H2] = 0.10 mol/L and [S2] = 0.40 mol/L.The value of Keq is calculated using the ratio

A (0.10)(0.40) (0.50) B. (0.10) 2 (0.40) (0.50)2

C. (0.50) (0.10)(0.50) D. (0.50) 2 (0.10)2(0.40)

8. Consider the following equilibrium: 2NO(g) + Cl2(g) ⇄ 2NOCl(g) Keq = 12 At equilibrium, [NOCl] = 1.60 mol/L and [NO] = 0.80 mol/L. The [Cl2] is

A. 0.17 mol/L B. 0.27 mol/L C. 0.33 mol/L D. 3.0 mol/L

9. Consider the following equilibrium: I2(s) + H2O(l) ⇄ H+(aq) + I-

(aq) + HOI(aq)

The equilibrium constant expression for the above system is

A. Keq = [H+][I-]

B. Keq = [H+][I-][HOI]

C. Keq = [H + ][I - ][HOI] [I2][H2O] D. Keq = [H + ][I - ][HOI] [H2O]

10. Consider the following equilibrium: 2CO(g) + O2(g) ⇄ 2CO2(g)

The ratio used to calculate the equilibrium constant is

A. [2CO] 2 [O 2] [2CO2]2

B. [2CO2] 2 [2CO]2[O2] C. [CO] 2 [O 2] [CO2]2

D. [CO2] 2 [CO]2[O2]

11. Consider the following equilibrium: 2Fe(s) + 3H2O(g) ⇄ Fe2O3(s) + 3H2(g)

The equilibrium constant expression is

A. Keq = [Fe2O3][H2] 3 [Fe]2[H2O]3

B. Keq = [Fe2O3][3H2]

[2Fe] [3H2O]

C. Keq = [H2] 3 [H2O]3

D. Keq = [H2]3

12. Consider the following equilibrium: N2O4(g) ⇄ 2NO2(g) Keq = 0.133At equilibrium, the [N2O4] is equal to

A. 0.133 [NO2] B. [NO2] 0.133 C. 0.133 [NO2]2

D. [NO2] 2 0.133

13. Consider the following equilibrium: 4KO2(s) + 2H2O(g) ⇄ 4KOH(s) + 3O2(g)

The equilibrium constant expression is A. Keq = [KOH] 4 [O 2] 3 [KO2]4[H2O]2

B. Keq = [O2] 3 [H2O]2

C. Keq = [KO2] 4 [H 2O] 2 [KOH]4[O2]3 D. Keq = [H2O]2 [O2]3

14. Consider the following equilibrium: C(s) + H2O(g) ⇄ CO(g) + H2(g)

The contents of a 1.00 L container at equilibrium were analyzed and found to contain 0.20 mol C, 0.20 mol H2O, 0.60 mol CO and 0.60 mol H2. The equilibrium constant is

A. 0.11 B. 0.56 C. 1.8 D. 9.015. Consider the following equilibrium: N2O4(g) ⇄ 2NO2(g) Keq = 4.61 x 10-3

A 1.00 L container at equilibrium was analyzed and found to contain 0.0200 moles NO2. At equilibrium, the concentration of N2O4 is

A. 0.0868 mol/L B. 0.230 mol/L C. 4.34 mol/L D. 11.5 mol/L

16. Consider the following equilibrium: CH4(g) + H2O(g) ⇄ CO(g) + 3H2(g) Keq= 5.7 At equilibrium, the [CH4] = 0.40 mol/L [CO] = 0.30 mol/L and [H2] = 0.80 mol/L. The [H2O] is

A. 0.067 mol/L B. 0.11 mol/L C. 2.2 mol/L D. 5.3 mol/L17. Consider the following equilibrium: H2(g) + I2(g) ⇄ 2HI(g)

At equilibrium, the [H2] = 0.020 mol/L. [I2] = 0.020 mol/L

and [HI] = 0.160 mol/L. The value of the equilibrium constant is A. 2.5 x 10-3

B. 1.6 x 10-2

C. 6.4 x 101

D. 4.0 x 102

18. Consider the following constant expression: Keq = [CO2]. Which one of the following equilibrium systems does the above expression represent?

A. CO2(g) ⇄ CO2(s)

B. PbO(s) + CO2(g) ⇄ PbCO3(s)

C. CaCO3(s) ⇄ CaO(s) + CO2(g)

D. H2CO3(aq) ⇄ H2O(l) + CO2(aq)

19. Given the following equilibrium system: Br2(g) ⇄ Br2(l)

The equilibrium constant expression for the above system is A. Keq = [Br2(l)]

[Br2(g)] B. Keq = [Br2(g)] C. Keq = 1 __

[Br2(g)] D. Keq = [Br2(g)] [Br2(g)]

20. Consider the following equilibrium: CO(g) + 2H2(g) ⇄ CH3OH(g) + 91 kJ

A change in temperature of the above system increases the value of the equilibrium constant. The new state of equilibrium was established by a shift

A. Left as a result of a decrease in temperature B. Right as a result of a decrease in temperature C. Left as a result of an increase in temperature D. Right as a result of an increase in temperature 21. Consider the equilibrium: SrCO3(s) ⇌ SrO(s) + CO2(g) In a 2.5 L container

at equilibrium there are 2.42 g CO2, 1.00 g SrCO3 and 1.00 SrO.Which of the following is the value of Keq?A. 0.022B. 0.011C. 0.020D. 91

23. Consider the following equilibrium: CH4(g) + H2O(g) ⇌ CO(g) + 3H2(g) At equilibrium, 1.20 mol CH4, 1.20 mol H2O, 0.080 mol CO and 0.040 mol H2 are present in a 2.0 L container. What is the value of Keq ?A. 4.3 x 10-6

B. 2.2 x 10-2

C. 2.2 x 10-4

D. 8.9 x 10-7

24. Consider the following equilibrium: Cr2O7

2-(aq) + 2OH-

(aq) ⇌ 2CrO42-

(aq) + H2O(l) The concentration of ions at equilibrium was measured at a specific temperature and found to be [CrO4

2-] = 0.100 M, [Cr2O72-] = 0.20 M, and [OH-] = 0.11 M.

What is the Keq?A. 41 B. 4.13C. 0.83 D. 0.11

25. Consider the following equilibrium:Cr2O72-

(aq) + 2OH-(aq) ⇌ 2CrO4

2-(aq) + H2O(l) Keq = 4.14

The concentration of ions at equilibrium was measured at a specific temperature and found to be [Cr2O7

2-] = 0.100 M and [OH-] = 0.20 M. What is the equilibrium [CrO42-]?

A. 0.017 MB. 0.083 MC. 0.13 MD. 0.32 M


(aq) + 2OH-(aq) ⇌ 2CrO4

2-(aq) + H2O(l) Keq = 4.14

The concentration of ions at equilibrium was measured at a specific temperature and found to be [CrO4

2-] = 0.100 M and [OH-] = 0.20 M. What is the equilibrium [Cr2O72-]?

A. 0.060 MB. 0.083 MC. 0.13 MD. 0.32 M


(aq) + 2OH-(aq) ⇌ 2CrO4

2-(aq) + H2O(l) Keq = 4.14

The concentration of ions at equilibrium was measured at a specific temperature and found to be [CrO4

2-] = 0.100 M and [Cr2O72-] = 0.20 M. What is the equilibrium [OH-]?

A. 0.012 MB. 0.083 MC. 0.13 MD. 0.11 M

28. Consider the following equilibrium: CH4(g) + H2O(g) ⇌ CO2(g) + 3H2(g)

Keq = 5.67 An equilibrium mixture of this system was found to contain the following concentrations: [CH4] = 0.59 M , [H2O] = 0.63 M, [CO2] = 0.25 M.What was the equilibrium [H2]?A. 0.26 MB. 0.64 MC. 2.0 MD. 8.4 M

Equilibrium Quiz # 5 Calculations and Trial Keq

1. Consider the following equilibrium: N2(g) + O2(g) ⇄ 2NO(g) Keq = 0.010Initially, a 1.0 L container is filled with 0.40 mol of N2, 0.10 mol of O2 and 0.080 mol of NO. As the system approaches equilibrium, the

A. [NO], [N2] and [O2] remain unchangedB. [NO] increases and both [N2] and [O2] decreaseC. [NO] decreases and both [N2] and [O2] increaseD. [NO] decreases and both [N2] and [O2] remain unchanged

2. Consider the following equilibrium: 2O2(g) + N2(g) ⇄ N2O4(g)

When 2.0 mol of O2 and 3.0 mol of N2 were placed in a 10.0 L container at 25oC, the value of Keq=0.90. If the same number of moles of reactant were placed in a 5.0 L container at 25oC, the equilibrium constant would be

A. 0.011 B. 0.45 C. 0.90 D. 1.803. Consider equilibrium system at 900oC: H2O(g) + CO(g) ⇄ H2(g) + CO2(g)

Initially, 5.0 moles of H2O and 4.0 moles of CO were reacted. At equilibrium, it is found that 2.0 moles of H2 are present. How many moles of H2O remain in the mixture?

A. 1.0 moles B. 2.0 moles

C. 3.0 moles D. 4.0 moles 4. Consider the following equilibrium: PCl5(g) ⇄ PCl3(g) + Cl2(g) Keq=33.3

Predict what will occur when 2.0 mol of PCl5, 3.0 mol of PCl3 and 4.0 mol of Cl2 are placed in a 1.0 L container and allowed to establish equilibrium.

A. [PCl5] will increase B. [PCl3] and [Cl2] will both increase C. [PCl5] and [Cl2] will both increase D. [PCl5] and [PCl3] will both decrease

5. Consider the equilibrium system: CO(g) + 2H2(g) ⇄ CH3OH(g) ∆H= -18kJIn order to increase the value of Keq for this reaction, you could

A. Increase [CO] B. Increase the volume C. Decrease [CH3OH] D. Decrease the temperature

6. Consider the following: SO2Cl2(g) ⇄ SO2(g) + Cl2(g)

A 1.0 L container is initially filled with 2.0 mol of SO2Cl2. As the reaction proceeds towards equilibrium, the rate of the forward reaction

A. Increases and the [SO2] increases B. Increases and the [SO2] Decreases C. Decreases and the [SO2] increases D. Decreases and the [SO2] decreases 7. Consider the following: 2NO2(g) ⇄ N2O2(g) Keq=1.20

A 1.0 L of flask is filled with 1.4 mol NO2 and 2.0 mol N2O4. To reach equilibrium, the reaction proceeds to the

A. Left as Trial Keq > Keq B. Left as Trial Keq < Keq C. Right as Trial Keq > Keq D. Right as Trial Keq < Keq

8. Consider the following: 2C(s) + O2(g) ⇄ 2CO(g)

A 1.0 L flask is initially filled with 2.00 mol C and 0.500 mol O2. At equilibrium the [O2] is 0.250 mol/L. The Keq value is

A. 0.444 B. 1.00 C. 2.00 D. 2.25 9. Consider the following: 2H2O(g) ⇄ 2H2(g) + O2(g)

When 0.1010 mol H2O is placed in a 1.000 L container, equilibrium is established. The equilibrium concentration of O2 is 0.0010 mol/L. the equilibrium concentrations of H2O and H2 are

[H2O] [H2]A 0.0990 0.0020

B 0.1000 0.0010C 0.1005 0.0005D 0.1010 0.0020

10. Which of the following equilibrium systems most favors the products? A. Cl2(g) ⇄ 2Cl(g) Keq=6.4 x 10-39

B. Cl2(g) + 2NO(g) ⇄ 2NOCl(g) Keq=3.7 x 108

C. Cl2(g) + 2NO2(g) ⇄ 2NO2Cl(g) Keq=1.8 D. 2HCl(g) ⇄ H2(g) + Cl2(g) Keq=2.0 x 10-3

11. Consider the equilibrium: H2O(g) + Cl2O(g) ⇄ 2HOCl(g) Keq= 9.0 x 10-2

A 1.0 L flask contains a mixture of 1.8 x 10-1 mol H2O. 4.0 x 10-4 mol Cl2O, and 8.0 x 10-2 mol HOCl . To establish equilibrium, the system will proceed to the

A. Left as Trial Keq > Keq B. Left as Trial Keq < Keq C. Right as Trial Keq > Keq D. Right as Trial Keq < Keq 12. Consider the following equilibrium: 2O3(g) ⇄ 3O2(g) Keq=55

If 0.060 mol of O3 and 0.70 mol of O2 are introduced into a 1.0 L vessel, the A. Ktrial > Keq and the [O2] increases B. Ktrial < Keq and the [O2] increases C. Ktrial > Keq and the [O2] decreases D. Ktrial < Keq and the [O2] decreases 13. Consider the following equilibrium: CO(g) + Cl2(g) ⇄COCl2(g)

At equilibrium, a 2.0 L sample was found to contain 1.00 mol CO, 0.500 mol Cl2 and 0.100 mol COCl2. The Keq value for the above system is

A. 0.40 B. 0.20 C. 2.5 D. 5.0 14 Consider the following equilibrium: 2SO2(g) + O2(g)⇄2SO3(g) Keq=4.0

In an experiment, 0.40 mol SO2(g), 0.20 mol O2(g) and 0.40 mol SO3(g) are placed into a 1.0 liter container. Which of the following statements relates the changes in [SO2] and [O2] as equilibrium becomes established?

A. The [SO2] and [O2] increase B. The [SO2] and [O2] decrease C. The [SO2] and [O2] do not change D. The [SO2] increases and the [O2] decreases 15. Consider the following equilibrium system: H2(g) + S(s) ⇄ H2S(g)

In a 1.0 L container at equilibrium there are 0.050 mol H2, 0.050 mol S and 1.0 mol H2S. The value of Keq is

A. 2.5 x 10-3

B. 5.0 x 10-2

C. 2.0 x 101

D. 4.0 x 102

16. Consider the following equilibrium and experimental data:

N2O4(g) ⇄ 2NO2(g) Initial Equilibrium[N2O4] [NO2] [N2O4] [NO2]

Trial 1 0.0400 M 0.0000 M 0.0337 M 0.0125 MTrial 2 0.0200 M 0.0600 M 0.0429 M 0.0141 M

Which of the following represents the Keq value?A. 0.00464B. 0.371C. 0.742D. 216

17. Consider the following equilibrium: Cl2(g) + 2NO(g) ⇌ 2NOCl(g) Keq = 5.0At equilibrium, [Cl2] = 1.0 M and [NO] = 2.0 M. What is the [NOCl] at equilibrium? A. 0.80 MB. 0.89 MC. 4.5 MD. 10 M

18. Consider the following equilibrium: Cl2(g) + 2NO(g) ⇌ 2NOCl(g) If 12.0 moles of Cl2, 10.24 moles of NO, and 2.00 moles NOCl are placed in a 2.00 L container and the system moves to the right to get to equilibrium, If there are 10.0 moles NOCl at equilibrium, calculate the Keq. A. 0.996 B. 5.58 C. 1.12 D. 4.98

19. What will cause the value of Keq for an exothermic reaction to decrease?A. increasing the pressureB. increasing the temperatureC. decreasing the temperatureD. decreasing the surface area

20. Consider the following: H2(g) + I2(g) ⇌ 2HI(g) Initially, some HI is placed into a 1.0 L container. At equilibrium there are 0.010 mol H2, 0.010 mol I2 and 0.070 mol HI present. How many moles of HI were initially added to the container?A. 0.060 molB. 0.070 molC. 0.080 molD. 0.090 mol

21. Consider the following equilibrium: 3NO2(g) ⇌ N2O5(g) + NO(g).Initially, some NO2, N2O5 and NO were placed in a container and allowed to reach equilibrium. When equilibrium was established, it was found that the pressure had increased. Which of the following explains what happened?A. Trial Keq > Keq so the system shifted left.B. Trial Keq < Keq so the system shifted left.C. Trial Keq > Keq so the system shifted right.D. Trial Keq < Keq so the system shifted right.

22. Consider the following equilibrium: 3NO2(g) ⇌ N2O5(g) + NO(g).Initially, 8.00 moles NO2 were placed in a 2.0 L container and allowed to reach equilibrium. The equilibrium concentration of NO was 1.10 M. Calculate the Keq.A. 1.7B. 1.9C. 3.5

D. 0.050

23. Consider the following equilibrium: 3NO2(g) ⇌ N2O5(g) + NO(g).At a different temperature, 4.00 M NO2 were placed in a 2.0 L container and allowed to reach equilibrium. The equilibrium concentration of NO2 was 1.00 M. Calculate the Keq.A. 0.11B. 1.0C. 3.0D. 10.

24. Consider the reaction: 2HBr(g) ⇌ H2(g) + Br2(g) Keq = 49.0If 4.0 M HBr is initially placed into a container, what will be the equilibrium [HBr]?A. 2.0 MB. 3.7 MC. 5.3 MD. 8.8 M

25. Consider the reaction: 2HBr(g) ⇌ H2(g) + Br2(g) Keq = 49.0If 0.120 M H2, 0.120 M Br2 and 0.01714 M HBr are placed into a container at 44 0 C, which of the following is true as equilibrium is approached? A. [Br 2] decreases significantly.B. [HBr] decreases significantly. C. [H 2] decreases significantly.D. [H 2] remains the same.

26. Consider the reaction: 2HBr(g) ⇌ H2(g) + Br2(g) Keq = 49.0If 1.20 M H2, 1.20 M Br2 and 1.00 M HBr are placed into a container at 44 0 C, which of the following is true as equilibrium is approached? A. [Br 2] decreases significantly.B. [HBr] decreases significantly. C. [H 2] decreases significantly.D. [H 2] remains the same.

27. Which Keq is most likely to favour the formation of reactants?

A. Keq = 1.65 x 10 4 B. Keq = 5.69 x 10 -11 C. Keq = 3.95 x 10 -11 D. Keq = 7.67 x 10 4

28. Which Keq is most likely to favour the formation of products?

A. Keq = 1.65 x 10 -4 B. Keq = 5.69 x 10 -11 C. Keq = 3.95 x 10 -11 D. Keq = 7.67 x 10 -4

29. Consider the following equilibrium system: 2NO (g) + Cl2(g) ⇌ 2NOCl (g) + 25 kJIn which direction will the equilibrium shift and what happens to the value of Keq when the temperature of the system is increased?

Shift Keq A. right increases B. right decreases C. left increases D. left decreases

30. Consider the following equilibrium system: 2NO (g) + Cl2(g) ⇌ 2NOCl (g) + 25 kJIn which direction will the equilibrium shift and what happens to the value of Keq when NO is added?

Shift Keq A. right increases B. right constant C. left increases D. left constant

31. Consider the following equilibrium: 2COF2(g) ⇌ CO2(g) + CF4(g)

Initially, 0.32 M CO2 and 0.40 M CF4 are placed in a container. At equilibrium, it is found that the [COF2] is 0.16 M. What is the value of Keq?A. 0.026B. 1.5C. 9.3D. 3.0

32. Consider the following equilibrium: CCl4(g) ⇌ C(s) + Cl2(g) Initially, 0.62 mol CCl4 was placed in a 2.0L container. At equilibrium, [Cl2] = 0.060 M. Which of the following is the value of Keq?A. 0.00039 B. 0.24C. 0.014D. 0.78

33. Consider the following equilibrium: 2COF2(g) ⇌ CO2(g) + CF4(g) Initially, 0.16 M CO2 and 0.20 M CF4 are placed in a container. At equilibrium, it is found that the [COF2] is 0.080 M. What is the value of Keq?A. 0.12B. 1.5C. 8.0D. 3.0

Equilibrium Quiz #6 Enthalpy and Entropy 1. In which of the following reactions does the tendency towards minimum enthalpy and maximum entropy

oppose each other?A. 3O3(g) ⇄ 2O2(g) ΔH = +285 KJB. 1/2O2(g) + O2(g) ⇄ NO2(g) ΔH = +34 KJC. 2H2O(g) ⇄ 2H2(g) + O2(g) ΔH = +484 KJD. P4(s) + 6H2(g) ⇄ 4PH3(g) ΔH = +37 KJ

2. In which of the following systems will the factors of entropy and enthalpy both favour the reactants.

A. 3C(s) + 3H2(g) + heat ⇄ C3H6(g)

B. PCl5(g) + heat ⇄ PCl3(g) + Cl2(g)

C. NH4Cl(s) + heat ⇄ NH4+

(aq) + Cl-(aq)

D. Cl2(g) + 2HI(g) ⇄ I2(g) + 2HI(g) + heat 3. For an exothermic reaction at equilibrium, an increase in temperature will cause the equilibrium to shift

A. left and the Keq increasesB. left and the Keq decreasesC. right and the Keq increasesD. right and the Keq decreases

4. Consider the equilibrium: COCl2(g) ⇄ CO(g) + Cl2(g) Keq = 8.1 x 10-4

For the above system,A. [COCl2] < [CO][Cl2]B. [COCl2] = [CO][Cl2]C. [COCl2] > [CO][Cl2]D. [COCl2] = 1/[CO][Cl2]

5. The value of the equilibrium constant will change whenA. a catalyst is usedB. temperature changesC. product concentrations changeD. the volume of a gaseous system changes

6. In an exothermic equilibrium reaction involving only gases, the value of the Keq can be decreased by

A. adding some reactant gasB. removing some reactant gasC. increasing the temperatureD. decreasing the temperature

7. Consider the equilibrium: H2(g) + CO2(g) ⇄ CO(g) + H2O(g) ΔH = +41KJThe temperature of the above equilibrium system is increased while kept at a constant volume. A new state of equilibrium is established in which there isA. an increase in [CO] and a decrease in Keq

B. an increase in [CO] and a increase in Keq

C. an increase in [CO2] and a decrease in Keq

D. an increase in [CO2] and a increase in Keq

8. Consider the following equilibrium: 2NO2(g) ⇄ N2O4(g) + 59KJ

For the above reaction,A. both minimum enthalpy and maximum entropy favour the products.B. both minimum enthalpy and maximum entropy favour the reactants.C. minimum enthalpy favours reactants and maximum entropy favours products.D. minimum enthalpy favours products and maximum entropy favours reactants.

9. In which of the following does entropy decrease?

A. NaCl(s) → Na+(aq) + Cl-

(aq)

B. 4NO(g) + 6H2O(g) → 4NH3(g) + 5O2(g)

C. 2NaCHCO3(s) → Na2CO3(s) + CO2(g) + H2O(g)

D. CaCO3(s) + HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l)

10. Consider the following possible reaction: N2O(g) + NO2(g) → 3NO(g) + heat

Which of the following statements is correct?A. Minimum enthalpy and maximum entropy both favour the products.B. Minimum enthalpy and maximum entropy both favour the reactants.C. Minimum enthalpy favours the reactants and maximum entropy favours the products.D. Minimum enthalpy favours the products and maximum entropy favours the reactants.

11. Consider the following equilibrium: COCl2(g) ⇄ CO(g) + Cl2(g)

At equilibrium in a 1.0L container, there are 3.0 mol COCl2, 0.49 mol CO, and 0.49 mol Cl2. At constant temperature the volume of the above system is decreased to 0.50L. When equilibrium is reestablished theA. concentrations of all three gases have increased

B. concentrations of all three gases have decreasedC. [COCl2] has increased and [CO] and [Cl2] have decreasedD. [COCl2] has decreased and [CO] and [Cl2] have increased

12. Chemical systems move toward positions of

A. minimum enthalpy and maximum entropyB. maximum enthalpy and minimum entropyC. constant enthalpy and constant entropyD. maximum enthalpy and maximum entropy

13. Hydrogen gas dissociates into atomic hydrogen as follows:

H2(g) ⇄ 2H(g) Keq = 1.2 x 10-71

The value of the equilibrium constant for the above system indicates thatA. the reaction rate is very slowB. the equilibrium is exothermicC. reactants are favoured in this equilibriumD. a catalyst is necessary to establish equilibrium

14. Consider the following reaction:Na2CO3(s) + HCl(aq) ⇄ 2NaCl(aq) + CO2(g) + H2O(l) ΔH = -27.7 KJIn this reaction,A. Minimum enthalpy and maximum entropy both favour the products.B. Minimum enthalpy and maximum entropy both favour the reactants.C. Minimum enthalpy favours the products and maximum entropy favours the reactants.D. Minimum enthalpy favours the reactants and maximum entropy favours the products.

15. In an endothermic equilibrium system, theA. Minimum enthalpy and maximum entropy both favour the products.B. Minimum enthalpy and maximum entropy both favour the reactants.C. Minimum enthalpy favours the products and maximum entropy favours the reactants.D. Minimum enthalpy favours the reactants and maximum entropy favours the products.

16. Which of the following describes how a Keq value is related to the relative concentrations of reactants and products?

Keq value Relative ConcentrationI. large [products] > [reactants]II. large [reactants] > [products]III. small [products] > [reactants]IV. small [reactants] > [products]A. I onlyB. IV onlyC. I and IV onlyD. II and III only

17. Consider the following equilibrium: N2(g) + O2(g) ⇌ 2NO(g) + 25.6 kJUnder certain conditions, Keq = 0.00056. When conditions are changed, Keq becomes 0.0256. Which of the following could account for this?A. [N2] was changed.B. A catalyst was added.C. Temperature was decreased.D. Temperature was increased.

18. Consider the following equilibrium: N2O(g) + NO2(g) ⇌ 3NO(g) + 120 KJUnder certain conditions, Keq = 2.5. When conditions are changed, Keq becomes 0.15. Which of the following could account for this?A. [N2O] was added.B. A catalyst was added.C. Temperature was decreased.D. Temperature was increased.

19. Reacting systems tend toward which of the following?Entropy Enthalpy

A. minimum maximumB. minimum minimumC. maximum minimumD. maximum maximum

20. Consider the following equation: NH4NO3(g) ⇌N2O(g) + 2H2O(g) + 37 kJWhich of the following is true?

Enthalpy FavoursEntropy Favours OutcomeA. reactants reactants does not occurB. products products completionC. reactants products equilibriumD. products reactants equilibrium

21. Consider: energy + N2O4(g) ⇄ 2NO2(g) The system above reaches equilibrium. Considering enthalpy and entropy factors, which of the following is true with respect to the forward reaction?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.

22. Which of the following forward reaction changes would result in the most products?Entropy Enthalpy

A. decreasing decreasingB. increasing decreasingC. decreasing increasingD. increasing increasing

23. Which of the following forward reaction changes would result in the most reactants?Entropy Enthalpy

A. decreasing decreasingB. increasing decreasingC. decreasing increasingD. increasing increasing

24. Which of the following forward reaction changes would result equilibrium?Entropy Enthalpy

A. decreasing decreasingB. increasing decreasingC. decreasing increasingD. constant constant

25. When the temperature of an endothermic equilibrium is increased, which of the following will happen?A. Equilibrium will shift left and [products] will increase.B. Equilibrium will shift left and [products] will decrease.C. Equilibrium will shift right and [reactants] will increase.

D. Equilibrium will shift right and [reactants] will decrease.

26. When the temperature of an exothermic equilibrium is decreased, which of the following will happen?A. Equilibrium will shift left and [products] will increase.B. Equilibrium will shift left and [products] will decrease.C. Equilibrium will shift right and [reactants] will increase.D. Equilibrium will shift right and [reactants] will decrease.

27. When the temperature of an endothermic equilibrium is increased, which of the following will happen?A. Equilibrium will shift left and the Keq will increase.B. Equilibrium will shift right and the Keq will increase.C. Equilibrium will shift left and the Keq will stay constant.D. Equilibrium will shift right and the Keq will stay constant.

28. Consider: 2Li(s) + H2O(l) ® 2LiOH(aq) + H2(g) ΔH = -256 kJ?What will entropy and enthalpy factors favour?

Entropy EnthalpyA. products reactantsB. products productsC. reactants reactantsD. reactants products

29. Consider: 3C(s) + 3H2(g) + heat ⇄ C3H6(g)

What will entropy and enthalpy factors favour?Entropy Enthalpy

A. products reactantsB. products productsC. reactants reactantsD. reactants products

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

enthalpy entropyA. increases increasesB. increases decreasesC. decreases increasesD. decreases decreases

Web Review 1. Describe the changes in reactant and product concentration as equilibrium is approached. 2. Describe the changes in the forward and the reverse rates as equilibrium is approached. 3. State three conditions that are necessary to achieve equilibrium. 4. Assuming all three conditions are present, describe what would happen if only reactants

are placed in a container. 5. Assuming all three conditions are present, describe what would happen if only

products are placed in a container.

6. Describe the relationship between the size of the equilibrium constant, large, small, or about 1, and the relative amounts of reactants or products.

7. Describe each of the following:

Dynamic equilibrium, LeChatelier's principle, Ktrial, Enthalpy, Entropy Macroscopic property.

8. Describe the effect of temperature on the equilibrium constant for an exothermic and

endothermic reaction. 9. Describe the effect of changing the temperature, pressure , volume, concentration or

adding a catalyst on the value of the equilibrium constant. 10. What is the only variable that will change the value of the equilibrium constant. 11. What are the phases of the compounds that are not included in the equilibrium

expression.12. Write the equilibrium expression for: 4A(g) + 3B(aq) ⇄ 2C(l) + 3D(s)

13. Pick the best Keq for each of the reactions. Keq = 100 Keq = 0.01 Keq = 1.0

a) Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g) + 152kJ

b) 3C(s) + 3H2(g) ⇄ C3H6(g) ΔH = +20.4 kJ

c) 2Pb(NO3)2(s) + 597 kJ ⇄ 2PbO(s) +4NO2(g) + O2(aq)

14. For each reaction in equilibrium describe the shift for the following changes: increasing

temperature, increasing pressure, decreasing volume, adding a gaseous product and removing an aqueous reactant.

a) Zn(s) + 2HCl(aq) ⇄ ZnCl2(aq) + H2(g) + 152kJ b) A(aq) + 6B(g) ⇄ 2C(g) + 4D(g) ΔH= +56kJ

15. Zn(s) + 2HCl(aq) ⇄ ZnCl2(aq) + H2(g) + 152kJ

Give three ways to increase the yield of the reaction.

Give five ways to increase the rate of the reaction.

16. A(aq) + 6B(g) ⇄ 2C(g) + 2D(g) ΔH= +56kJ Give three ways to increase the yield of the reaction.

Give five ways to increase the rate of the reaction.

17. What is equal at equilibrium? 18. What is constant at equilibrium? 19. Which reaction has the greatest yield? Why?

a) Keq = 8.0 x 10-12 b) Keq = 7.0 x 10-11

20. Which reaction has the smallest yield?

a) Keq = 1.0 x 10-15 b) Keq = 9.0 x 10-15

21. Which has the greater entropy?

a) H2O(s) b) H2O(l) c) H2O(g)

22. Which has the greater enthalpy?a) H2O(s) b) H2O(l) c) H2O(g)

Hint: Consider H2O(s) → H2O(l) Draw a potential energy diagram. Which side is higher?

23. Review your kinetics test. There will be 5 questions on this test from kinetics. 24. Consider the following equilibrium system: SO3(g) + NO(g)⇄NO2(g) + SO2(g)

a) Describe what happens to the forward and reverse reaction rate immediately after

adding SO3(g)

b) Describe what happens to the forward and reverse reaction rate immediately after removing NO2(g)

c) Describe what happens to the forward and reverse reaction rate immediately after adding a catalyst .

d) Describe what happens to the forward and reverse reaction rate after a new equilibrium has formed compared to the original equilibrium after removing NO2(g)

e) Describe what happens to the forward and reverse reaction rate after a new equilibrium has formed compared to the original equilibrium after adding SO3(g)

f) Describe what happens to the forward and reverse reaction rate after a new equilibrium has formed compared to the original equilibrium after adding a catalyst .

g) Describe what happens to the forward and reverse reaction rate after a new

equilibrium has formed compared to the original equilibrium after decreasing the volume of the container.

h) Describe what happens to the reactant and product concentrations after a new

equilibrium has formed compared to the original equilibrium after decreasing the volume of the container.

Part 2 Calculations1. SO3(g) + NO(g) ⇄ NO2(g) + SO2(g) [SO3] = 0.400M [NO] = 0.480M

[NO2] = 0.600M [SO2] = 0.450M Keq = 0.800 at 100ºCa) Show by calculation that this reaction mixture is not at equilibrium at 100ºC.b) What will happen to [SO3] and [SO2] as the system moves to equilibrium?

2. Consider the equilibrium below:

Co(H2O)6+2

(aq) + 2Cl-1(aq) ⇄ Co(H2O)6Cl2(aq) + 2H2O(l)

pink blueIf the colour of the equilibrium mixture is pink at 5ºC and blue at 60ºC, is the reaction endothermic or exothermic?

3. SO3(g) + H2O(g) ⇄ H2SO4(l)

If The equilibrium concentrations are :[SO3] = 0.400M [H2O] = 0.480M [H2SO4] = 0.600M. Calculate the value of the equilibrium constant.

4. 2SO2(g) + O2(g) ⇄ 2SO3(g)

4.00 moles of SO2 and 5.00 moles O2 are placed in a 2.00 L container at 200ºC and allowed to reach equilibrium. If the equilibrium concentration of O2 is 2.00M, calculate the Keq.

5. 2SO2(g) + O2(g) ⇄ 2SO3(g)

If at equilibrium [O2] = 0.500M and [SO3] = 0.400M and the equilibrium constant is the same as question 4 at 200ºC, calculate the [SO2].


2NO2(g) ⇄ N2O4(g) 2.00 moles of NO2 are placed in a 1.00 L flask and allowed to react. At equilibrium 1.80M NO2 are present. Calculate the Keq.

7. SO3(g) + NO(g) ⇄ NO2(g) + SO2(g) Keq = 0.800 at 100ºC

If 4.00 moles of each reactant is placed in a 2.00L container, calculate all equilibrium concentrations at 100ºC.

8. Keq = 0.0183 at 150ºC for: 2HI(g) ⇄ H2(g) + I2(g)

If 3.00 moles of HI is placed in a 5.00 L container and allowed to establish equilibrium, what are all equilibrium concentrations?

9. Consider the following equilibrium in a 5.00 L container:

CO (g) + H2O (g) ⇄ CO2(g) + H2 (g) At equilibrium, there is 1.0 mole of CO, 3.0 moles of H2O, 3.0 moles CO2, and 3.0 moles of H2. If 2.0 moles of CO are now added, find the equilibrium [CO2].Hint: first calculate the Keq, then do an ICE chart with the initial concentrations after CO is added.

Equilibrium Practice Test # 1 1. Consider the following reaction mechanism:

Step1: NO(g) + O3(g) → NO2(g) + O2(g)

Step2: O(g) + NO2(g) → NO(g) + O2(g)

The catalyst is:A. O2

B. O3

C. NO

D. NO2

2. Consider the following reaction: 2NH3(g) ⇄ N2(g) + 3H2(g)

A flask is initially filled with NH3. As the system approaches equilibrium, the rate of the forward reactionA. increases as the rate of the reverse reaction decreasesB. decreases as the rate of the reverse reaction increasesC. increases as the rate of the reverse reaction increasesD. decreases as the rate of the reverse reaction decreases

3. Consider the following reaction:

Na2CO3(s) + 2HCl(aq) → 2NaCl(aq) + CO2(g) + H2O(l) ΔH = -153 KJIn this reactionA. minimum enthalpy and maximum entropy both favour the productsB. minimum enthalpy and maximum entropy both favour the reactantsC. minimum enthalpy favours products and maximum entropy reactantsD. minimum enthalpy favours reactants and maximum entropy products

4. In all systems at equilibrium, theA. concentration of reactants is less than the concentration of the productsB. concentration of reactants and the concentration of the products are equalC. concentration of reactants is greater than the concentration of the productsD. concentration of reactants and the products are constant

5. Consider the following mechanism: Step 1: N2O(g) → N2(g) + O(g)

Step 2: N2O(g) + O(g) → N2(g) + O2(g)

A reactant in the overall equation is

A. OB. O2

C. N2

D. N2O 6. Chemical systems tend to move toward positions of

A. minimum enthalpy and maximum entropy.B. maximum enthalpy and minimum entropy.C. minimum enthalpy and minimum entropy.D. maximum enthalpy and maximum entropy.

7. An equilibrium system shifts left when the

A. rate of the forward reaction is equal to the rate of the reverse reaction.B. rate of the forward reaction is less than the rate of the reverse reaction.C. rate of the forward reaction is greater than the rate of the reverse reaction.D. rate of the forward reaction and the reverse reaction are constant.

8. A 1.00 L flask contains a gaseous equilibrium system. The addition of reactants to this flask results in a

A. shift left and a decrease in the concentration of the products.B. shift left and a increase in the concentration of the products.C. shift right and a decrease in the concentration of the products.D. shift right and a increase in the concentration of the products.

9. Consider the following equilibrium: CH4(g) + H2O(g) + heat ⇄ CO(g) + 3H2(g)

In which of the following will both stresses shift the equilibrium to the right?A. a decrease in temperature and a decrease in volumeB. a increase in temperature and a decrease in volume

C. a decrease in temperature and a increase in volumeD. a increase in temperature and a increase in volume

10. Consider the following equilibrium: 2SO2(g) + O2(g) ⇄ 2SO3(g) ∆H = -198 kJ

There will be no shift in this equilibrium whenA. more O2 is added.B. a catalyst is added.C. the volume is increased.D. the temperature is increased.

11. Consider the following equilibrium: 2Fe(s) + 3H2O(g) ⇄ Fe2O3(s) + 3H2(g)

The equilibrium expression is

A. Keq = [Fe2O3][H2] 3 B. Keq = [Fe2O3][3H2] [Fe]2[H2O]3 [2Fe][3H2O]

C. Keq = [H2] 3 D. Keq = [ H2]3

[H2O]3

12. Consider the following equilibrium: N2O4(g) ⇄ 2NO2(g) Keq = 0.133

At equilibrium, the [N2O4] is equal to

A. 0.133 B. [NO2][NO2] 0.133

C. 0.133 D. [NO2] 2

[NO2]2 0.133 13. Which of the following equilibrium systems most favours the products?

A. Cl2(g) ⇄ 2Cl(g) Keq = 6.4 x 10-39

B. Cl2(g) + 2NO(g) ⇄ 2NOCl(g) Keq = 3.7 x 108

C. Cl2(g) + 2NO2(g) ⇄ 2NO2Cl(g) Keq = 1.8D. 2HCl(g) ⇄ H2(g) + Cl2(g) Keq = 2.0 x 10-7

14. Consider the following equilibrium: 4KO2(s) + 2H2O(g) ⇄ 4KOH(s) + 3O2(g)

The equilibrium expression is

A. Keq = [KOH] 4 [O 2] 3 B. Keq = [O2] 3 [KO2]2[H2O]2 [ H2O]2

C. Keq = [KO2] 4 [H 2O] 2 D. Keq = [ H2O] 2

[KOH]4[O2]3 [O2]3

15. Consider the following equilibrium: N2(g) + O2(g) ⇄ 2NO(g) ∆H = +181 kJWhen the temperature is decreased, the equilibrium:A. shifts left and the Keq value increasesB. shifts left and the Keq value decreasesC. shifts right and the Keq value increasesD. shifts right and the Keq value decreases

16. Consider the following equilibrium: CaCO3(s) + 556 kJ ⇄ CaO + CO2(g)

The value of the equilibrium constant will increase whenA. CO2 is added.B. CO2 is removed.C. the temperature is increased.D. the temperature is decreased.

17. Consider the following equilibrium: C(s) + H2O(g) ⇄ CO(g) + H2(g)

The contents of a 1.00 L container at equilibrium were analyzed and found to contain 0.20 mole C, 0.20 mole H2O, 0.60 mole CO, and 0.60 mole H2, The equilibrium constant isA. 0.11B. 0.56C. 1.8D. 0.0

18. Consider the following equilibrium: N2O4(g) ⇄ 2NO2(g) Keq = 4.61 x 10-3

A 1.00 L container at equilibrium was analyzed and found to contain 0.0200 mole NO2. At equilibrium, the concentration of N2O4 isA. 0.0868 MB. 0.230 MC. 4.34 MD. 11.5 M

19. Consider the following potential energy diagram:

The forward reaction is

A. exothermic and the ∆H = -50 kJB. endothermic and the ∆H = +50 kJC. exothermic and the ∆H = -225 kJD. endothermic and the ∆H = +225 kJ


A closed container is initially filled with H2O and CO. As the reaction proceeds to equilibrium the A. [CO] and [CO2] both increase

B. [CO] and [CO2] both decreaseC. [CO] increases and [CO2] decreasesD. [CO] decreases and [CO2] increases

21. Consider the equilibrium: H2(g) + I2(g) ⇄ 2HI(g) The pressure of the system is increased by reducing the

volume. When comparing the new equilibrium with the original equilibrium,A. all concentrations remain constantB. the concentrations of all species have increasedC. reactant concentrations have increased while products decreasedD. reactant concentrations have decreased while products increased

22. Consider the following equilibrium: N2O4(g) ⇄ 2NO2(g) A 1.00 L container is initially filled with 0.200

moles of N2O4. At equilibrium, 0.160 moles NO2 are present. What is the equilibrium concentration of N2O4?A. 0.040 MB. 0.080 MC. 0.120 MD. 0.160 M

PE(kJ)

Progress of Reaction

50kJ225kJ

23. Equilibrium is dynamic process because theA. macroscopic properties are not changingB. mass of the reactants equals the mass of the productsC. forward and reverse reactions continue to occurD. concentrations of reactants and products are constant

24. Consider the following equilibrium: C(s) + 2H2(g) ⇄ CH4(g) The addition of H2 will cause the equilibrium

to shift to the A. left and [CH4] will increaseB. left and [CH4] will decreaseC. right and [CH4] will increaseD. right and [CH4] will decrease

25. Given the following system: 2CrO42-

(aq) + 2H+(aq) ⇄ Cr2O7

2-(aq) + H2O(l) Which of the following

chemicals, when added to the above equilibrium, would result in a decrease in [CrO42-]?

A. NaOHB. HNO3

C. Na2CrO4

D. Na2Cr2O7

26. Addition of a catalyst to an equilibrium systemA. increases the value of the Keq.B. increases the yield of the products.C. has no effect on the rates of the reaction.D. increases the rate of formation of both reactants and products.

27. Consider the following reaction: 2B(s) + 3F2(g) ⇄ 2BF3(g) The equilibrium expression is

A. Keq = [2BF3] [3F2]

B. Keq = [F2] 3 [BF3]

C. Keq = [BF3] 2 [F2]3

D. Keq = [BF3] 2 [B][F2]3

28. Consider the following equilibrium: 2NO(g) ⇄ N2(g) + O2(g) Keq = 2.01 x 1030

The value of the equilibrium constant indicates that the A. [NO]2 < [N2][ O2]B. [NO]2 > [N2][ O2]C. [NO] = [N2][ O2]D. [NO] > [N2][ O2]

29. Consider the equilibrium: H2(g) + I2(g) ⇄ 2HI(g)

At equilibrium the [H2} = 0.020 M, [I2] = 0.020 M, and [HI] = 0.160 M. The value of the equilibrium constant is:A. 2.5 x 10-3

B. 1.6 x 10-2

C. 6.4 x 101

D. 4.0 x 102

30. Consider the equilibrium: H2O(g) + Cl2O(g) ⇄ 2HOCl(g) Keq = 9.0 x 10-2

A 1.0 L flask contains a mixture of 1.8 x 10-1 mole H2O, 4.0 x 10-4 mole Cl2O, and 8.0 x 10-2 mole HOCl. To establish equilibrium, the system will proceed to the A. left because the trial Keq > Keq

B. left because the trial Keq < KeqC. right because the trial Keq > KeqD. right because the trial Keq < Keq

31. Consider the following equilibrium: SO2(g) + NO2(g) ⇄ SO3(g) + NO(g) + energy

The equilibrium does not shift with a change inA. volumeB. temperatureC. concentration of productsD. concentration of reactions

32. Consider the following equilibrium : SO2Cl2(g) + energy ⇄ SO2(g) + Cl2(g)

When the temperature is decreased, the equilibrium shiftsA. left and the [SO2Cl2] increases B. left and the [SO2Cl2] decreasesC. right and the [SO2Cl2] increasesD. right and the [SO2Cl2] decreases

33. Consider the following equilibrium: NH3(g) + HCl(g) ⇄ NH4Cl(s) + energy

Which of the following will result in a decrease in the mass of NH4Cl?

A. adding NH3

B. removing HClC. decreasing the volumeD. decreasing the temperature

34. Consider the following equilibrium: PCl3(g) + Cl2(g) ⇄ PCl5(g)

When 0.40 moles of PCl3 and 0.40 moles of Cl2 are placed in a 1.00 L container and allowed to reach equilibrium, 0.244 mole of PCl5 are present. From this information, the value of the Keq isA. 0.10B. 0.30C. 3.3D. 10

Subjective 1. Concentrations of H2, I2, and HI in a mixture at equilibrium at 425 oC were found to be 1.52 x 10-2 M, 3.55

x 10-2 M, and 2.57 x 10-1 M respectively. Calculate the equilibrium constant.H2(g) + I2(g) ⇄ 2HI(g)

2. 4.00 moles of PCl5 are placed in a 2.00 L container and goes to equilibrium at

200 oC. If 0.60 moles of PCl5 are present at equilibrium, calculate the equilibrium constant. PCl5(g) ⇄ PCl3(g) + Cl2(g)

3. An equilibrium system has a Keq = 50 at 0 oC and a Keq = 80 at 20 oC. a) As the temperature was increased, which direction did the reaction shift?

b) Is the reaction endothermic or exothermic? 4. If the initial [H2] = 0.200 M and [I2] = 0.200 M and the Keq = 55.6 at 20 oC, calculate the equilibrium

concentration of all molecules.H2(g) + I2(g) ⇄ 2HI(g)

5. Consider the following data obtained for the following equilibrium:

Fe3+(aq) + SCN-

(aq) ⇄ FeSCN2+(aq)

[Fe3+] [SCN-] [FeSCN2+]

Experiment 1 3.91 x 10-2 M 8.02 x 10-5 M 9.22 x 10-4 M

Experiment 2 6.27 x 10-3 M 3.65 x 10-4 M ?

Calculate [FeSCN2+] in experiment 2.

6. 1.60 moles CO, 1.60 moles H2O, 6.00 moles CO2, and 6.00 moles H2 are put in a 2.00 L container at 600 oC.

CO(g) + H2O(g) ⇄ CO2(g) + H2(g) Keq = 10.0

a) Show by calculation the reaction is not at equilibrium.

b) Which way will the reaction shift in order to achieve equilibrium?

c) Calculate the equilibrium concentration of CO2.

Equilibrium Practice Test # 2 1. The slowest of the following reactions is:

A. Ag+(aq) + Cl-

(aq) → AgCl(s)

B. H+(aq) + OH-

(aq) → 2H2O(l)

C. 3Ba2+(aq) + 2PO4

3-(aq) → Ba3(PO4)2(aq)

D. Cu(s) + 2Ag+(aq) → Cu2+

(aq) + 2Ag(s)

2. The rate of a chemical reaction is equal to the slope of the line with axes labelled

x-axis y-axis

A. time rateB. mass timeC. volume of gas timeD. time concentration

3. Consider the following reaction: CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) + heat

The diagram that represents the relationship between rate and temperature is:

4. Which of the following describes the energy of colliding particles as reacting molecules approach each other?

KE PEA. decreases increasesB. increases decreasesC. decreases remains constantD. remains constant increases

5. The average kinetic energy per molecule can be increased by

A. adding a catalystB. increasing pressureC. increasing temperatureD. increasing reactant concentration

Rate

Temperature

Rate

Temperature

Rate

Temperature

Rate

Temperature

A. B.

C. D.

6. Consider the following reaction: C(s) + 2H2(g) ⇄ CH4(g) ΔH = -74.8 kJWhich of the following will cause an increase in the value of the Keq?A. increasing [H2]B. decreasing the volumeC. finely powdering the C(s)

D. decreasing the temperature 7. Consider the following equilibrium: H2(g) + I2(g) ⇄ 2HI(g)

At equilibrium [H2] = 0.00220 M, [I2] = 0.00220 M, and [HI] = 0.0156 MThe value of the Keq isA. 3.10 x 10-4

B. 1.99 x 10-2

C. 5.03 x 101

D. 3.22 x 103

8. Consider the rate diagram for the following reaction: 2HI(g) ⇄ H2(g) + I2(g)

Which of the following occurs at t1?A. addition of H2

B. addition of HIC. addition of a catalystD. a decrease in volume

9. Chemical equilibrium is said to be dynamic because

A. the reaction proceeds quicklyB. the mass of the reactants is decreasingC. the macroscopic properties are constantD. both forward and reverse rates are occurring

10. Which equation has the largest value of KeqA. N2(g) + O2(g) ⇄ 2NO(g) ΔH = 21 kJB. C2H6(g) ⇄ 2C(s) + 3H2(g) ΔH + 83 kJC. H2(g) + 1/2O2(g) ⇄ H2O(g) ΔH = -240 kJD. Ca(s) + 3H2O(l) ⇄ Ca(OH)2(aq) + H2(g) ΔH = -240 kJ

11. The value of the Keq can be changed by

A. adding a catalystB. changing the temperatureC. changing the reactant concentrationD. changing the volume of the container

12. Consider the following equilibrium: PCl3(g) + Cl2(g) ⇄ PCl5(g)

When 0.40 mole of PCl3 and 0.40 mole of Cl2 are placed in a 1.00 L container and allowed to reach equilibrium, 0.244 mole of PCl5 are present. From this information, the value of the Keq is

Rate

Time t1

forward

reverse

A, 0.10B. 0.30C. 3.3D. 10

13. Consider the following equilibrium: PCl3(g) + Cl2(g) ⇄ PCl5(g) Keq = 2.30

A 1.0 L container is filled with 0.05 mole PCl5, 1.0 mole PCl3, and 1.0 mole Cl2. The system proceeds to the A. left because the Trial Keq > KeqB. left because the Trial Keq < KeqC. right because the Trial Keq > KeqD. right because the Trial Keq < Keq

14. Given the following system: 2CrO42-

(aq) + 2H+(aq) ⇄ Cr2O7

2-(aq) + H2O(l)

Which of the following chemicals, when added to the above system at equilibrium, would result in a decrease in [Cr2O7

2-]?A. NaOHB. HNO3

C. Na2CrO4

D. Na2Cr2O7

15. What is the Keq expression for the following equilibrium?3Fe(s) + 4H2O(g) ⇄ Fe3O4(s) + 4H2(g)

A. Keq = [H2]4

B. Keq = [H2] [H2O]

C. Keq = [H2] 4 [H2O]4

D. Keq = [Fe2O3][H2] 4 [Fe][H2O]4

16. Consider the following equilibrium: 2O3(g) ⇄ 3O2(g) Keq = 65

Initially 0.10 mole of O3 and 0.10 mole of O2 are placed in a 1.0 L container, Which of the following describes the changes in concentrations as the reaction proceeds towards equilibrium?

[O3] [O2]A. decreases decreasesB. decreases increasesC. increases decreasesD. increases increases

17. Consider the following equilibrium: 2CrO4

2-(aq) + 2H+

(aq) ⇄ Cr2O72-

(aq) + H2O(l)

yellow orangeAn unknown solution is added to an orange equilibrium system until the sample turns yellow. The solution could be A. KNO3

B. NaOHC. NH4NO3

D. CH3COOH

18. Consider the following equilibrium: CH3COOH(aq) ⇄ CH3COO-

(aq) + H+(aq) + heat

A stress was applied at time t1 and the data plotted on the following graph:The stress imposed at time t1 is the result of

time t1

[H+]

A. the addition of HClB. decreasing the temperatureC. the addition of NaCH3COOD. increasing the volume of the container

19. 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 Keq increasesB. left and the Keq decreasesC. right and the Keq increasesD. right and the Keq decreases

20. Addition of a catalyst to an equilibrium system

A. increases the value of the KeqB. increases the yield of the productC. has no effect on the rates of the reactionD. increases the rates of formation of both reactants and products

21. Ammonia, NH3, is produced by the following reaction:

N2(g) + 3H2(g) ⇄ 2NH3(g) + energyWhich of the following would result in the highest concentration of ammonia at equilibrium? A. increasing the temperature and increasing the pressureB. decreasing the temperature and increasing the pressureC. increasing the temperature and decreasing the pressureD. decreasing the temperature and decreasing the pressure


2NO2(g) ⇄ N2O4(g) Keq = 1.15

P.E.

Progress of the reaction

The equilibrium concentration of NO2 is 0.50 mol/L. Calculate the equilibrium concentration of N2O4(g).

A. 0.22 mol/LB. 0.29 mol/LC. 0.43 mol/LD. 0.58 mol/L


H2(g) + I2 ⇄ 2HI(g) Keq = 50.0 What is the value Keq for the reaction rewritten as:

2HI(g) ⇄ H2(g) + I2(g) Keq = ?A. -50.0B. 0.0200C. 25.0D. 50.0

24. Consider the following equilibrium: 2NOCl(g) ⇄ 2NO(g) + Cl2(g)

A flask is filled with NOCl, NO, and Cl2(g). Initially there were a total of 5.0 moles of gases present. When equilibrium is reached, there are a total of 8.0 moles of gases present. Which of the following explains the observation?A. The reaction shifted left because the Trial Keq > KeqB. The reaction shifted left because the Trial Keq < KeqC. The reaction shifted right because the Trial Keq > KeqD. The reaction shifted right because the Trial Keq < Keq


4NH3(g) + 5O2(g) ⇄ 4NO(g) + 6H2O(g) + energyWhich of the following will cause the equilibrium to shift to the left?A. adding H2O(g)

B. removing some NO(g)

C. increasing the volumeD. decreasing the temperature

26. A catalyst is added to a system already at equilibrium. How are the forward and reverse reaction rates affected by the addition of the catalyst.

Forward Rate Reverse RateA. increases increasesB. increases constantC. constant decreasesD. constant constant

27. Consider the following equilibrium: 2NOBr(g) ⇄ 2NO(g) + Br2(g) Keq = 0.064

At equilibrium, a 1.00 L flask contains 0.030 mole NOBr and 0.030 mole NO. How many moles of Br2 are present?A. 0.0019B. 0.064C. 0.030D. 0.47

28. Which of the following does not apply to all chemical equilibrium systemsA. They are closed.B. The macroscopic properties are constantC. Forward and reverse rates are equalD. There are equal concentrations of reactants and products

29. The relationship between Ea and reaction rate is best represented as

30. The relationship between Keq and temperature for an exothermic reaction is best represented as

31. The relationship between reaction rate and temperature is best represented by

A. B.

C. D.

A. B.

C. D.

A. B.

C. D.

32. The relationship between Ea and temperature is best represented by 32. Methanol, CH3OH, can be produced by the following:

CO(g) + 2H2(g) ⇄ CH3OH(g) + energyThe conditions necessary to maximize the equilibrium yield of CH3OH areA. low temperature and low pressureB. high temperature and low pressureC. low temperature and high pressureD. high temperature and high pressure

33. Consider the following equilibrium: 2NO(g) + O2(g) ⇄ 2NO2(g) + energy

When the volume of the container is increased, the equilibrium shifts to the A. left and the Keq decreasesB. right and the Keq increasesC. left and the Keq remains constantD. right and the Keq remains comstant

34. Consider the following reaction:

C3H8(g) + 5O2(g) Š 3CO2(g) + 4H2O(g) ΔH = -2202 kJWhich of the following applies to the forward reaction?

Entropy EnthalpyA. increases increasesB. increases decreasesC. decreases increasesD. decreases decreases

Subjective


N2H4(g) + 2O2(g) ⇄ 2NO2(g) + 2H2O(g)

More oxygen is added to the above equilibrium. After the system re-establishes equilibrium, identify the substance(s), if any, that have a net

a) increase in concentration

b) decrease in concentration

A. B.

C. D.

2. Given the following equilibrium: H2(g) + I2(g) ⇄ 2HI(g)

Initially, 0.200 mole H2 and 0.200 mole I2 were placed into a 1.0 L container. At equilibrium, the [I2] is 0.040 M. Calculate the Keq.

3. Consider the following equilibrium: 2CrO4

2-(aq) + 2H+

(aq) ⇄ Cr2O72-

(aq) + H2O(l)

yellow orange

When HCl is added, the solution turns orange. Explain why this colour change occurs.

4. Consider the following equilibrium system: N2(g) + 3H2(g) ⇄ 2NH3(g) + energy

A 1.00 L container is filled with 7.0 mole NH3 and the system proceeds to equilibrium as indicated by the graph.

a) Draw and label the graph for N2 and H2. Fill in an ICE chart if you are not sure how to do this.

N2(g) + 3H2(g) ⇄ 2NH3(g)

ICE

b) Calculate the Keq for the above reaction.

2.0

8.0

6.0

4.0

M

NH3

5. Consider the following equilibrium 2NO(g) + O2(g) ⇄ 2NO2(g) Keq = 1.5

0.800 mole NO, 0.600 moles O2, and 0.400 moles NO2 are placed in a vessel that 2.0 L. Show by calculation that the reaction is not at equilibrium? What will happen to [O2] as equilibrium is approached?


SO3(g) + NO(g) ⇄ NO2(g) + SO2(g) Keq = 0.500 Exactly 0.100 mole SO3 and 0.100 mole NO were placed in a 1.00 L flask and allowed to go to equilibrium. Calculate the equilibrium concentration of SO2.

· web viewworksheet #4 le chatelier’s principle some co was added to the system and a new...

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