Equilibrium worksheet with answers

Woodhaven High School - Brownstown Charter Twp

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GO HERE for web site answers, they we placed here but the formatting Is bad in parts

iannonechem/Science/Chemistry/Iannone/equilibrium/equilibriumworkbookans wers

Power Point Lesson Notes- double click on the lesson number.

Worksheets Quiz

1. Approaching Equilibrium WS 1 Q
2. LeChatelier's Principle-1 WS 2
3. LeChatelier's Principle-2 WS 3 & 4 Q
4. LeChatelier's-3 & Start Lab WS 5
5. Lab Lechatelier's Questions 1-10 Conclusion
6. Haber/Graphing WS 6 & 7 Q
7. Equilibrium Constants WS 8 Q
8. Keq Calculations WS 9 & 10
9. K-trial & Size Keq WS 11 Q
10. Entropy & Enthalpy WS 12 Q
11. Review Web Review Practice Test 1
12. Review Practice Test 2 Quizmebc

Read Hebdon Unit 2

Worksheet #1 Approaching Equilibrium

Read unit II your textbook. Answer all of the questions. Do not start the questions until you have completed the reading. Be prepared to discuss your answers next period.

1. What are the conditions necessary for equilibrium? Must have a closed system. Must have a constant temperature. Ea must be low enough to allow a reaction.
2. What is a forward reaction versus a reverse reaction?

In a forward reaction, the reactants collide to produce products and it goes from left to right. In a reverse reaction, the products collide to produce reactants and it goes form right to left. 3. Why does the forward reaction rate decrease as equilibrium is approached? As the reaction goes to the right, the reaction concentration decreases and therefore, there are less reactant collisions causing the forward rate to decrease. 4. What are the characteristics of equilibrium? Forward rate is equal to the reverse rate. The concentration of reactants and products are constant.(not equal) Macroscopic properties are constant (color, mass, density, pressure, concentrations).

1. Define equilibrium. Equilibrium occurs when: Forward rate is equal to the reverse rate. The concentration of reactants and products are constant.(not equal) Macroscopic properties are constant. (color, mass, density, pressure, concentrations)
2. Define the word dynamic and explain its relevance to the concept of equilibrium. The word dynamic means that forward and reverse continue to occur.
3. Why does the reverse reaction rate increase as equilibrium is approached? The reverse reaction rate increases as equilibrium is approached because as the reaction goes from left to right,
4. 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)
5. Draw a PE Diagram for the reaction if PE of the reactants is 100 KJ/mole N 2 O 4 and Ea = 110 KJ/mole N 2 O4. N 2 O4 (g) <-----> 2 N02 (g) H= +58KJ (colorless) (brown)

If a catalyst was added to the reaction, what would happen to the PE Diagram, the forward rate, and the reverse rate?

PE Diagram The activation energy would decrease Forward rate Increase Reverse rate Increase

One mole of very cold, colorless N 2 O4 (g) is placed into a 1 glass container of room temperature. The reaction: N 2 O4 (g) ⇋ 2 N02 (g) H= +58KJ

The container will gradually increase the intensity of brown and then remain constant after 15 seconds. 20. Calculate the rate of N 2 O 4 consumption in (M/s) over the first 5s period and then the second 5s period. 0-5 sec. rate = 1 – 0. M = 0 M / s 5 sec 5-10 sec. rate = 0 – 0. M = 0 M / s 5 sec

Why is the rate greater over the first five minutes compared to the second five minutes (think in terms of reactant and product concentrations?

The reactant concentration has decreased and the product concentration increased. The forward rate has decreased and the reverse rate increased and because of this the overall net rate has decreased.

1. Calculate the rate of N0 2 production in (M/s) over the first 5s period and then the second 5s period. 0-5 sec. rate = 0 – 0.M = 0 M / s 5 sec 5-10 sec. rate = 0 – 0.M = 0 M / s 5 sec

How does the rate of formation of N0 2 compare to the rate of consumption of N 2 O 4? Remember, if you measure the reactants or products, it is still the overall rate. It is twice as great because of the stoichiometric relationship. 2moles NO 2 1mole N 2 O 4

1. What are the equilibrium concentrations of N 2 O 4 and N0 2?

[N 2 O 4 ]= 0 M Are they equal? No! [N0 2 ] = 0 M

1. Is the reaction over, when equilibrium has been achieved? If not, explain. No it is not. Although the concentrations are constant, the forward and reversereactions continueforever.
2. What are the necessary conditions to establish equilibrium? Must have a closed system.Must have a constant temperature. Ea must be low enough to allow areaction.
3. What are the characteristics of an equilibrium? Forward rate is equal to the reverse rate.The concentration of reactants and products are constant.(not equal)Macroscopic properties are constant. (color, mass, density, pressure, concentrations)

Worksheet #2 LeChatelier’s Principle

e

N 2 O 4 (g) ⇋ 2NO2(g) H = + 92 KJ

Shifts Shifts to Favor the Stress [N 2 O 4 ] [NO 2 ] Right or Left Reactants or Products

1. [N 2 O 4 ] is increased increases increases right products
2. [NO 2 ] is increased increases increases left reactants
3. Temp is increased decreases increases right products
4. [N 2 O 4 ] is decreased decreases decreases left reactants
5. [H 2 ] is decreased nochange nochange nochange nochange
6. [NO 2 ] is decreased decreases decreases right products
7. Temp is decreased increases decreases left reactants

4HCl (g) + O2 (g) ⇋ 2H 2 O(g) + 2Cl2 (g) + 98 KJ

Shifts Shifts to Favour the Stress [O 2 ] [H 2 O] [HCl] Right or Left Reactants or Products

1. [HCl] is increased decreases increases increases right products
2. [H 2 O] is increased increases increases increases left reactants
3. [O 2 ] is increased increases increases decreases right products
4. Temp is increased increases decreases increases left reactants
5. [H 2 O] is decreased decreases decreases decreases right products
6. [HCl] is decreased increases decreases decreases left reactants
7. [O 2 ] is decreased decreases decreases increases left reactants
8. Temp is decreased decreases increases decreases right products
9. A catalyst is added nochange nochange nochange nochange nochange

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

NH 3 addition increases decreases increases increases removal decreases increases decreases decreases

O 2 addition decreases increases increases increases

removal increases decreases decreases decreases

NO addition increases increases increases decreases

removal decreases decreases decreases increases

H 2 O addition increases increases decreases increases removal decreases decreases increases decreases

Increase in temperature: increases increases decreases decreases

Decrease in temperature: decreases decreases increases increases

Increase Presssure: increases increases increases increases

Decrease in pressure: decreases decreases decreases decreases We increased the volume- all concentrations go down

Addition of a catalyst: nochange nochange nochange nochange

An inert gas is added: nochange nochange nochange nochange

Worksheet #4 Le Chatelier’s Principle

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 right
2. C (s) + CO2 (g) + energy ⇋ 2 CO (g) increase temperature right
3. N 2 O4 (g) ⇋ 2 NO2 (g) increase total pressure left
4. CO (g) + H 2 O (g) ⇋ CO2 (g) + H2 (g) decrease total pressure nochange
5. 2 NOBr (g) ⇋ 2 NO (g) + Br2 (g) decrease total pressure right
6. 3 Fe (s) + 4 H 2 O (g) ⇋ Fe 3 O4 (s) + 4 H2 (g) add Fe(s) nochanges
7. 2SO2 (g) + O2 (g) ⇋ 2 SO3 (g) add catalyst nochanges
8. CaCO3 (s) ⇋ CaO (s) + CO2 (g) remove CO 2 (g) right
9. N2 (g) + 3 H2 (g) ⇋ 2 NH3 (g) increase [He (g)] nochange

Consider the following equilibrium system:

3 H2 (g) + N2 (g) ⇋ 2 NH3 (g) + Heat.

State what effect each of the following will have on this system:

Forward Rate has decreases Reverse Rate has decreases.

Consider the following equilibrium system

H2 (g) + I2 (g) ⇋ 2 HI (g)

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

1. The volume of the vessel is increased nochange
2. The pressure is increased nochange
3. A catalyst is added nochange

Consider the following equilibrium system:

3 Fe (s) + 4 H 2 O (g) <------> Fe 3 O4 (s) + 4 H2 (g)

State what effect each of the following will have on this system in terms of shifting. 21. The volume of the vessel is decreased nochange 22. The pressure is decreased nochange

1. More Fe is added to the system nochange
2. Some Fe 3 O 4 is removed from the system nochange
3. A catalyst is added to the system nochange

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 left 27. The pressure is decreased left 28. More Br 2 is added to the system right 29. Some NO is removed from the system left 30. A catalyst is added to the system nochange Consider the following equilibrium: Some CO was added to the system and a new equilibrium was established. 2CO (g) + O2 (g) <------> 2CO2 (g) + energy 31. Compare to the original system, the rates of the forward and reverse reactions of the new equilibrium. Forward Rate has increases Reverse Rate has increases

1. Compared to the original concentrations, after the shift, have the new concentrations increased or decreased? [CO] increases [O 2 ] decreases [CO 2 ] increases
2. Did the equilibrium shift favour the formation of reactants or products? products A catalyst was added to the system at constant volume and a new equilibrium was established. 2CO (g) + O2 (g) ⇋ 2CO2 (g) + energy
3. Compare to the original system, the rates of the forward and reverse reactions of the new equilibrium.

shift color change Increase in [H+] right Orange Increase in [CrO 4 2-] right Increase in [Cr 2 O 7 2-] left Decrease in [H+] left Yellow Decrease in [CrO 4 2-] left Increase in temperature right Orange Decrease intemperature left Yellow Add HCl (aq) right Orange Add NaOH left Yellow OH- reacts with H+ and lowers [H+] causing the reaction to shift left.

1. The copper (II) ion andcopper (II) hydroxide complex exist in equilibrium as follows:

Cu(OH)2 (aq) +4 H 2 O (l) ⇋ Cu(H 2 O) 4 2+(aq) +2 OH-(aq) + 215 kJ violet light blue

Describe how the above equilibrium will shift after each stressbelow:

shift colorchange Increase in [Cu(H 2 O) 4 2+] left Add NaOH left Violet Increase in [Cu(OH) 2 ] right Decrease in [Cu(H 2 O) 4 2+] right Decrease in[Cu(OH) 2 ] left Increase temperature left Violet Decrease temperature right Light Blue AddKCl (aq) no change nochange AddHCl (aq) right Light Blue

1. Consider the equilibriumthat follows:

4 HCl (g)+ 2 O2 (g) ⇋ 2 H 2 O (l) + 2 Cl 2 (g) + 98 kJ (yellow)

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

shift color change Increase in temperature left clear Increase [HCl] right yellow Decrease in [Cl 2 ] right Decrease temperature right yellow Add Ne at constant volume No Change

1. 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 change Increase in temperature right less green Increase [HCl] right less green Add NaCl right less green Decrease temperature left green Add NaOH (aq) left clear (reacts with HCl)

(check your solubility table for a possible reaction)

Add CuCl(s) no change no change Add AgNO 3 (aq) left green

(check your solubility table for a possible reaction)

Add CuNO 3 (aq) right because it contains the Cu+ ion.