chapters 17-18: kinetics and equilibrium class · web viewkey ideas collision theory states...

Chapters 17-18: Kinetics and Equilibrium Class Packet

Key Ideas

Collision theory states that a reaction is most likely to occur if reactant particles collide with the proper energy and orientation. (3.4d)

The rate of a chemical reaction depends on several factors: temperature, concentration, nature of reactants, surface area, and the presence of a catalyst. (3.4f)

Some chemical and physical changes can reach equilibrium. (3.4h) At equilibrium the rate of the forward reaction equals the rate of the reverse reaction. The measurable

quantities of reactants and products remain constant at equilibrium. (3.4i) LeChatelier’s principle can be used to predict the effect of stress (change in pressure, volume,

concentration, and temperature) on a system at equilibrium. (3.4j) Energy released or absorbed by a chemical reaction can be represented by a potential energy diagram.

(4.1c) Energy released or absorbed during a chemical reaction (heat of reaction) is equal to the difference

between the potential energy of the products and the potential energy of the reactants. (4.1d) A catalyst provides an alternate reaction pathway, which has a lower activation energy than an uncatalyzed

reaction. (3.4g) Heat is a transfer of energy (usually thermal energy) from a body of higher temperature to a body of lower

temperature. Thermal energy is the energy associated with the random motion of atoms and molecules. (4.2a)

Temperature is a measurement of the average kinetic energy of the particles in a sample of material. Temperature is not a form of energy. (4.2b)

The concepts of potential and kinetic energy can be used to explain physical processes that include: fusion (melting), solidification (freezing), vaporization (boiling, evaporation), condensation, sublimation, and deposition. (4.2c)

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Reactions Rates

1. In order for a reaction to occur the particles must __________________with proper ______________

and ________________. Therefore, the more collisions the reactant particle have, the faster the rate.

2. Recall 5 ways to increase the rate of reaction. Be specific.

1. __________________________________________

2. __________________________________________

3. __________________________________________

4. __________________________________________

5. __________________________________________

3. Matches have the potential to burn on fire. But they will not without sufficient activation energy.

Look up and explain what activation energy means and what type of activation energy the matches

need.

Regents Questions

1. Which event must always occur for a chemical reaction to take place?A) formation of a precipitateB) formation of a gasC) effective collisions between reacting particlesD) addition of a catalyst to the reaction system

2. Increasing the temperature increases the rate of a reaction byA) lowering the activation energyB) increasing the activation energyC) lowering the frequency of effective collisions

between reacting moleculesD) increasing the frequency of effective collisions

between reacting molecules

3. After being ignited in a Bunsen burner flame, a piece of magnesium ribbon burns brightly, giving off heat and light. In this situation, the Bunsen burner flame providesA) ionization energyB) activation energy

C) heat of reactionD) heat of vaporization

4. As the number of effective collisions between reacting particles increases, the rate of reactionA) DecreasesB) increasesC) remains the same

5. In most aqueous reactions as temperature increases, the effectiveness of collisions between reacting particlesA) DecreasesB) increasesC) remains the same

6. Given the reaction: Mg + 2 H2O Mg(OH)2 + H2

At which temperature will the reaction occur at the greatest rate?A) 25ºC B) 50ºCC) 75ºC D) 100ºC

7. A 5.0-gram sample of zinc and a 50.-2


milliliter sample of hydrochloric acid are used in a chemical reaction. Which combination of these samples has the fastest reaction rate?A) a zinc strip and 1.0 M HCl(aq)B) a zinc strip and 3.0 M HCl(aq)C) zinc powder and 1.0 M HCl(aq)D) zinc powder and 3.0 M HCl(aq)

8. A 1.0-gram piece of zinc reacts with 5 milliliters of HCl(aq). Which of these conditions of concentration and temperature would produce the greatest rate of reaction?A) 1.0 M HCl(aq) at 20.°CB) 1.0 M HCl(aq) at 40.°CC) 2.0 M HCl(aq) at 20.°D) 2.0 M HCl(aq) at 40.°C

9. At STP, which 4.0-gram zinc sample will react fastest with dilute hydrochloric acid?A) lump C) barB) powdered D) sheet metal

10. Given the reaction:Fe(s) + 2 HCl(aq) FeCl2(aq) + H2(g)

In this reaction, 5 grams of powdered iron will react faster than a 1-gram piece of solid iron because the powdered iron

A) has less surface areaB) has more surface areaC) is less denseD) D) is more dense

11. Which statement best explains the role of a catalyst in a chemical reaction?A) A catalyst is added as an additional reactant

and is consumed but not regenerated.B) A catalyst limits the amount of reactants used.C) A catalyst changes the kinds of products

produced.D) A catalyst provides an alternate reaction

pathway that requires less activation energy.

12. Which change would most likely increase the rate of a chemical reaction?A) decreasing a reactant's concentrationB) decreasing a reactant's surface areaC) cooling the reaction mixtureD) adding a catalyst to the reaction mixture

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Enthalpy Review

Enthalpy of the ______________ of a reaction measured by subtracting: __________________ minus

__________________. These values can be found on table ________.

1. Which compound was the most stable when synthesized on Table I? ____________________________

2. Which reaction on table I requires the most heat to react? ____________________________________

3. How much heat is required to produce 1 mole of C2H2? _______________________________________

4. How much heat is required to produce 2 moles of C2H2? ______________________________________

5. Is the decomposition of C2H6 endothermic or exothermic? ____________________________________

6. If you reverse a reaction what happens to the magnitude of ∆H? What happens to the sign?

7. If the ∆H for a given forward reaction is positive, will the reverse reaction be endothermic or exothermic?

Reaction ∆H (kJ) Endothermic and Exothermic

CH4(g) + 2O2(g) → CO2(g) + 2H2O(l)

2H2(g) + O2(g) → 2H2O(g)

C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l)

C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(l)

4H2O(l) + 3CO2(g) → C3H8(g) + 5O2(g)

N2(g) + 3H2(g) → 2NH3(g)

CO2(g) → C(s) + O2(g)

NH4Cl(s) → NH4+(aq) + Cl-(aq)

2CO2(g) + 4H2O(l) → 2CH3OH(l) + 3O2(g)

2Al2O3(s) → 4Al(s) + 3O2(g)

*CO(g) + ½O2(g) → CO2(g)

*4NO(g) → 2N2(g) + 2O2(g)

Methane (CH4) combining with oxygen to produce carbon Endo or Exo4


dioxide and waterPotassium nitrate dissociating into a positive potassium ionand a negative nitrate ion

Endo or Exo

Sodium hydroxide dissociating into a positive sodium ionand a negative hydroxide ion

Endo or Exo

Carbon monoxide combining with oxygen to formcarbon dioxide

Endo or Exo

**A positive lithium ion combining with a negative bromineion to form lithium bromide

Endo or Exo

Regents Questions

1. Given the equation representing a reaction: CH4(g) + 2O2(g) 2H2O(g) + CO2(g) + heat

Which statement is true about energy?A) The reaction is exothermic because it

releases heat.B) The reaction is exothermic because it

absorbs heat.C) The reaction is endothermic because it

releases heat.D) The reaction is endothermic because it

absorbs heat.

2. Which balanced equation represents an endothermic reaction?

A) C(s) + O2(g) CO2(g)B) CH4(g) + 2O2(g) CO2(g) + 2H2O( )C) N2(g) + 3H2(g) 2NH3(g)D) N2(g) + O2(g)2NO(g)

3. Given the balanced equation representing a reaction at 101.3 kPa and 298 K:

N2(g) + 3H2(g) 2NH3(g) + 91.8 kJWhich statement is true about this reaction?

A) It is exothermic and H equals –91.8 kJ.B) It is exothermic and H equals +91.8 kJ.C) It is endothermic and H equals –91.8 kJ.D) It is endothermic and H equals +91.8 kJ.

4. Which expression represents the H for a chemical reaction in terms of the potential energy, PE, of its products and reactants?A) PE of products + PE of reactantsB) PE of products – PE of reactantsC) PE of products × PE of reactantsD) PE of products / PE of reactants

5. Given the balanced equation:4Fe(s) + 3O2(g) 2Fe2O3(s) + 1640 kJWhich phrase best describes this reaction?

A) endothermic with H = +1640 kJB) endothermic with H = –1640 kJC) exothermic with H = +1640 kJD) exothermic with H = –1640 kJ

6. According to Table I, which salt releases energy as it dissolves?A) KNO3 B) LiBr C) NH4NO3 D) NaCl

7. In a chemical reaction, the difference between the potential energy of the products and the potential energy of the reactants is calledA) activation energyB) kinetic energyC) activated complexD) heat of reaction

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Heating and Cooling Curves

1. Label the line segments with their phase(s).

2. What is this substance’s melting point? _________

3. What is this substance’s boiling point? __________

4. Does this represent an endothermic or exothermic reaction?

5. Heat is being released at 60.0 kilojoules per minute.

How much heat is released when the substance freezes?

6. Label the point with the most kinetic energy with a star.

__________________________________________________________________________________________

7. Draw six particles of this substance as it looks for the first line segment in the box below.

8. Draw six particles of this substance as it looks for the last line segment in the box below.

9. At which point is the potential energy the highest? Label it with a star.

10. What is the boiling point of this substance? _____________

11. What is the melting point of this substance? _____________

12. What would you expect the graph to do if the substance continued to be heated?

Heat Table I

1. Are the following endo or exothermic?

CH4 + 2O2 CO2 + 2H2O _____ 2CH3OH + 3O2 2CO2 + 4H2O + 1452kJ _____

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H2 + I2 2HI _____ The dissolving of NaOH _____

25.69kJ + NH4NO3 NH4+ + NO3

- _____ The dissolving of LiBr _____

2. Circle the more stable compound in each pair:

H2O(g) OR H2O(l) NH3 OR Al2O3

HI OR NO C2H6 OR C2H4

3. Circle the compound which is more likely to form in each pair:

CO2 from elements OR CO2 from CO NO OR NO2

C2H6 OR C2H2 NH3 OR HI

4. Will the following feel hot or cold?

Dissolving KNO3 _____________ Dissolving LiBr _____________

Burning CH4 in O2 _____________ Forming Al2O3 _____________

5. Write a balanced equation for the following reactions including the heat as a reactant or product:

The formation of H2O from its elements __________________________________________

The decomposition of C2H6 __________________________________________

The dissolving of NH4Cl __________________________________________

The evaporation of water from Li+ and Br- __________________________________________

Specific Heat

Specific heat is defined as the amount of heat (in _____) needed to raise ____ gram of a substance ____˚C.

Every substance has its own specific heat depending on the bonds and forces it has.

1. When you wake up in the morning and touch the floor, at first the carpet feels warm. The wood floor in the hallway is a bit chilly, but the tile floor in the bathroom is FREEZING! However, your whole house is probably 68˚F. What quality is different about each of these surfaces? Which has the highest specific heat?

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2. At the park, why do you tend to steer clear of metal benches and prefer wooden picnic benches? Which has a lower specific heat?

3. Water has a high specific heat due to its hydrogen bonds. Explain why the fish is so happy in the picture below.

4. Based on the specific heat values in the table below, why do Al, Cu, Au, Fe and Hg have very low values? (What do they have in common?)

5. Based on your answer to question 2 do you expect wood to have a higher or lower specific heat than these substances and why?

6. Glass is often called an insulator because it has a ___________ specific heat.

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Heat Calculations

Define the following terms with units: q: ________________ c: ____________________

m: ________________ ΔT: ___________________

Answer the following questions using the heat formula. Show work with units and significant figures.

1. How many Joules of energy are needed to change the temperature of 100.0 grams of water from 20.0C to 40.0C?

2. How many kilojoules of energy are needed to change the temperature of 15.0 grams of water from 35.0C to 75.0C?

3. If the temperature of water is changed from 10.0C to 35.0C by the addition of 350.0J, how many grams were heated?

4. If the temperature of water is changed from 100.0C to 250.0C by the addition of 5000.0J, how many grams were heated?

5. If 3500.0J of energy are applied to 150.0 grams of water at 50.0C, what is the final temperature?

6. If 425J of energy are released from 25.0 grams of water at 25.0C, what is the final temperature?

7. Look at the rearranged equation for heat, solved for specific heat. What are the units of specific heat based on this rearranged equation?

8. What is the specific heat of silver if an 80.0 gram sample is heated from 24.0C to 49.0C by adding 468.2J?

9. What is the specific heat of copper if a 75.0 gram sample of copper is heated from 20.0C to 24.0C by adding 117J?

10. The specific heat of aluminum is 0.88J/gC. How many joules of heat does it take to heat 50.0 grams of aluminum from 20.0 to 70.0C?

11. What is the change in temperature when 3.00 grams of Iron (specific heat = 0.45J/gC) is subjected to 350.0.J of energy?

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12. What mass of Aluminum (specific heat = 0.902 J/gC) can be heated from 25.0C to 90.0C with the addition of 100.0J of heat?

13. How many joules of heat must be released in order to change the temperature of 50.0 grams of air (specific heat 1.01 J/gC) from 35.0C to 25.0C?

_______________________________________________________________________________________

Base answers to questions 14-17 on the diagram:

14. How much heat is added to change the

substance from the coldest to the warmest

pure liquid state?

15. If the specific heat of this substances in the liquid

phase is 3.56 J/gC calculate how many grams were

heated in question 11?

16. If the same sample is heated as a solid at 40C to 60C will it have the same specific heat? Show work to support your answer.

17. How much heat will need to be added to the same sample in order to raise the temperature from 20.0C to 40.0C? (Notice this is not on the graph, you must calculate it based on your answers above.)

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Heat of Vaporization and Fusion

Heat of Fusion of water: 334 J/gHeat of Vaporization of water: 2260 J/gSpecific Heat of gaseous water: 1.84 J/gCSpecific Heat of liquid water: 4.18 J/gCSpecific Heat of solid water: 2.09 J/gC

Show all work and answers with three significant figures and proper units. Write the formula(s) you used first then show your work.

1. How many Joules of heat are required to change the temperature of 200.0 grams of solid water from -20.0C to 0.0C?

2. How many Joules of heat are needed to change 200.0 grams of water from solid to liquid?

3. How many Joules of heat are required to change the temperature of 200.0 grams of liquid water from 0.0C to 100.0C?

4. How many Joules of heat are needed to change 200.0 grams of water from liquid to gas?

5. How many Joules of heat are required to change the temperature of 200.0 grams of gaseous water from 100.0C to 120.0C?

6. How many Joules of heat are required to change the temperature of 200.0 grams of solid water from -20.0C to 0.0C and then melt it?

7. How is your answer to question 6 related to your answers to questions 1 and 2?

8. Using the rule you obtained in question 7 and your answers to questions 1-5, how much heat is required to heat 200.0 grams of water from -20.0 to 120.0C?

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9. Draw a heating curve to show the phase changes that occurred during the processes described in questions 1-5. Label each segment with the phase(s) on the top of the line and the formula you used to determine the amount of heat added on the bottom of the line. Keep in mind the x axis should be the TOTAL heat used in the reaction and the y axis should be temperature in degrees Celsius.

Additional Questions:

10. How much heat is absorbed by 550.0g block of ice to raise the temperature from -15.0 to 0.0C?

11. How much heat is needed to vaporize 250.0 grams of water?

12. How much heat is released when 25.0 grams of water freezes?

13. Calculate the heat needed to change 50.0 grams of liquid water to gas at 100.0C.

14. Calculate the heat released when 125 grams of liquid water solidifies.

15. How much heat energy must be absorbed to raise the temperature of a 200.0 gram block of ice from -10.0 to 0.0C and then completely melt it to a liquid at the same temperature?

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16. How much energy would be required to heat the same 200.0 grams of liquid water in #15 (at 0.0C) to the normal boiling point of water and then vaporize it?

17. If the temperature of the 200.0 grams of steam generated in #12 were heated to a new temperature of 120.0C, how much energy would be absorbed?

18. What is the total amount of energy needed to heat 200.0 grams of ice at -10C to gas at 120.0C?

19. What is the total amount of energy needed to heat 125g of ice at -25C to gas at 135.0C? (Use a heating curve to help you).

20. The heat of vaporization of substance X is 250.0J/g. How much heat is needed to change 10.0 grams of X from liquid to gas?

21. The heat of fusion of substance Y is 125 J/g. How much heat is needed to change 25.0 grams of Y from solid to liquid?

22. The heat of sublimation of substance XY2 is 780.0 J/g. calculate the heat required to sublime 200.0 grams of XY2.

23. Hypothesize a possible heat of sublimation for water and give your reasoning.

Potential Energy Diagrams

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1. Define potential energy (PE).

2. Using the first diagram to the right, record the letter that describes each statement:a. Reactants PE: ___b. Products PE: ___c. Activated complex PE: ___d. Activation Energy: ___e. Heat of Reaction: ___

3. Is the diagram above depicting an endothermic or exothermic reaction? Defend your answer.

4. On the second diagram to the right find the value of the following statements in kJ:

a. Reactants PE: ___b. Products PE: ___c. Activated complex PE: ___d. Activation Energy: ___e. Heat of Reaction: ___f. Activation Energy of the

reverse reaction: ___g. Enthalpy of reverse reaction: ___


6. On the third diagram to the right find the value of the following statements in kJ for the uncatalyzed reaction:

a. Reactants PE: _____b. Products PE: _____c. Activated complex PE: _____d. Activation Energy: _____e. Heat of Reaction: _____f. Activation Energy of the

reverse reaction: _____g. Enthalpy of reverse reaction: _____


8. On the third diagram, what values changed for the catalyzed reactions? Give the new values:a. Reactants PE: _____b. Products PE: _____

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c. Activated complex PE: _____d. Activation Energy: _____e. Heat of Reaction: _____

9. For the reaction on table I that creates Aluminum oxide, sketch the following:

10. Using the reactions on table I, sketch a graph for the reaction that produces nitrogen monoxide:

11. Using the reactions on table I, circle if the following are endothermic or exothermic and which is higher: the potential energy of the products or the potential energy of the reactants:

a. Formation of CO2 from it’s elements Endo / Exo Products / Reactantsb. Formation of NH3 Endo / Exo Products / Reactantsc. Dissolving NH4Cl Endo / Exo Products / Reactantsd. Dissolving LiBr Endo / Exo Products / Reactantse. Combustion of CH4 Endo / Exo Products / Reactantsf. Combustion of C2H5OH Endo / Exo Products / Reactantsg. Decomposition of HI Endo / Exo Products / Reactantsh. Decomposition of C2H6 Endo / Exo Products / Reactants

Using the graph below please draw a reaction potential energy diagram for a reaction with the following characteristics:

Potential Energy of Reactants = 350 kJ/moleActivation Energy of Forward Reaction = 100 kJ/mole

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Potential Energy of Products = 150 kJ/mole

1. Is the reaction endothermic or exothermic?2. Please identify the following on the diagram you created in question #1. Place this letter above its corresponding line

segment on the graph and the value in the adjacent column.

Component of Potential Energy Diagram Symbol Value

Potential Energy of Reactants A

Potential Energy of Products B

Potential Energy of Activated Complex C

Heat of Reaction D

Activation Energy of Forward Reaction E

Activation Energy of Reverse Reaction F

3. Using a dotted line, show how the reaction potential energy diagram would be altered upon the addition of a catalyst to the reaction in the graph above.

4. If a catalyst were added, which lettered quantities, if any would change?

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Reaction Coordinate (X + Y → Z)

Potential Ener


Entropy

Entropy is the degree of ___________ in a substance. The symbol for change in entropy is ∆S. Solids are very ordered and have low entropy. Liquids and aqueous ions have ________ entropy than solids because they move about more freely. Gases have an even larger amount of entropy because their particles are spread out and are extremely free to move about. Nature always proceeds to a state of higher entropy (or randomness).

Determine whether the following reactions show an increase or decrease in entropy based on the individual states (s), (l), (aq), (g) within the reaction.

1) 2KClO3(s) 2KCl(s) + 3O2(g) _____________________________

2) H2O(l) H2O(s) _____________________________

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

4) NaCl(s) Na+(aq) + Cl-

(aq) _____________________________

5) KCl(s) KCl(l) _____________________________

6) CO2(s) CO2(g) _____________________________

7) H+(aq) + C2H3O2

-(aq) HC2H3O2(l) _____________________________

8) C(s) + O2(g) CO2(g) _____________________________

9) H2(g) + Cl2(g) 2HCl(g) _____________________________

10) Ag+(aq) + Cl-

(aq) AgCl(s) _____________________________

11) 2N2O5(g) 4NO2(g) + O2(g) _____________________________

12) 2Al(s) + 3I2(s) 2AlI3(s) _____________________________

13) H+(aq) + OH-

(aq) H2O(l) _____________________________

14) 2NO(g) N2(g) + O2(g) _____________________________

15) H2O(g) H2O(l) _____________________________

Reaction Enthalpy(endo/exo)

Entropy(Increases or decreases)

Favorable or not?

CO2(s) CO2(g)

I2(g) I2(s)

C(s) + O2(g) CO2(g)

4Al(s) + 2O2(g) 2 Al2O3(s)

2CO(g) + O2(g) 2CO2(g)

2H2(g) + O2(g) 2H2O(l)

Reaction Spontaneous or not? How did you know?

4Al(s) + 2O2(g) 2 Al2O3(s) +3351kJ Enthalpy:

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Entropy:

2CO(g) + O2(g) 2CO2(g) +566kJ Enthalpy:

Entropy:

NaOH(s) Na+(aq) + Cl-(aq) + 44.51kJ Enthalpy:

Entropy:

2C(s) + 2H2(g) + 52.4kJ C2H4(g) Enthalpy:

Entropy:

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LeChatelier’s Principle

Rules: 1. If a substance (or heat) is ADDED shift AWAY from that substance (or heat)2. If a substance (or heat) is TAKEN shift TOWARDS that substance (or heat)3. If pressure is added, there is less volume/room for moles. Shift towards side with less moles.4. If pressure is relieved, there is more room. Shift towards the side with more moles.5. Catalysts speed up the forward AND reverse reaction. Therefore equilibrium is unchanged.6. At equilibrium RATES are equal. Not amount!

1. Circle which direction the equilibrium will shift towards to relieve the stress and cite the rule used:2NH3(g) N2(g) + 3H2(g) + heat

Rule #a. Ammonia is added left right no effect _____b. Nitrogen is added left right no effect _____c. Hydrogen is added left right no effect _____d. Heat is added left right no effect _____e. Ammonia is removed left right no effect _____f. Nitrogen is removed left right no effect _____g. Hydrogen is removed left right no effect _____h. Heat is removed left right no effect _____i. Pressure is increased left right no effect _____j. Pressure is decreased left right no effect _____k. A catalyst is added left right no effect _____

2. Circle what will happen to the Nitrogen to relieve the stress:N2(g) + 3H2(g) + heat 2NH3(g)

a. Ammonia is removed increase decrease remain the sameb. Heat is added increase decrease remain the samec. Pressure is increased increase decrease remain the samed. Heat is removed increase decrease remain the samee. Ammonia is added increase decrease remain the samef. Hydrogen is removed increase decrease remain the sameg. A catalyst is used increase decrease remain the sameh. Pressure is decreased increase decrease remain the samei. Hydrogen is added increase decrease remain the same

3. In a closed soda bottle the following equilibrium exists: H3O+(aq) + HCO3

-(aq) 2H2O(l) + CO2(g)

a. When the cap is opened, the pressure decreases. Which way does the reaction shift?

b. Will opening the cap result in more or less carbon dioxide dissolved in the soda?

c. When the soda is left out on a hot day, which way does the equilibrium reaction shift?

d. Will heating the soda result in less or more carbon dioxide dissolved in the soda?

e. Why do soda companies recommend storing soda at cool temperatures with the cap on tight?19


4. List four changes you could make to the system in order to produce more phosphorous pentachloride:Cl2(g) + PCl3(g) PCl5(g)

_________________________________________________ _____________________________________________________

________________________________________________ _____________________________________________________

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

Colorless Brown

NO2 is placed in a flask at a constant temperature. Which of the following is true as the system approaches equilibrium?

a. The color gets darker as [NO2] increases.b. The color gets lighter as [NO2] decreases.c. The color gets darker as [N2O4] increases.d. The color gets lighter as [N2O4] decreases.

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

Colorless Brown

N2O4 is placed in a flask at a constant temperature. Which of the following is true as the system approaches equilibrium?

a. The color gets darker as [NO2] increases.b. The color gets lighter as [NO2] decreases.c. The color gets darker as [N2O4] increases.d. The color gets lighter as [N2O4] decreases.

7. Indicate how each of the following changes affects the amount of each gas in the system below, for which Hreaction = +9.9 kcal. H2(g) + CO2(g) H2O(g) + CO(g)

a) addition of CO2 ___ ___ ___

b) addition of H2O ___ ___ ___

c) addition of a catalyst ___ ___ ___ ___

d) increase in temperature ___ ___ ___ ___

e) decrease in the volume of the container ___ ___ ___ ___

8. How will the amount of chemicals at equilibrium be affected by each of the following: 2N2O(g) + O2(g) 4NO(g)

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a) adding N2O ___ ___

b) removing O2 ___ ___

c) increasing the volume of the container ___ ___ ___

d) adding a catalyst ___ ___ ___

9. How will the concentration of each chemical be affected by 4NH3(g) + 3O2(g) 2N2(g) + 6H2O(l)

a) adding O2 to the system ___ ___ ___

b) adding N2 to the system ___ ___ ___

c) removing H2O from the system ___ ___ ___

d) decreasing the volume of the container ___ ___ ___ ___

10. Match the change to the equilibrium system below with the letter of the appropriate response. Each letter can be used once, more than once, or not at all.

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

_____ 1) O2 is added to the reaction a) The equilibrium shifts to the right_____ 2) SO3 is removed from the reaction b) The equilibrium shifts to the left_____ 3) SO3 is added to the reaction c) there is no change in the equilibrium_____ 4) The pressure is increased

For each of the following, indicate the direction the equilibrium would shift and what would happen to the concentrations of each substance in equilibrium.

11. A small percentage of nitrogen gas and oxygen gas in the air combine at high temperatures found in automobile engines to produce NO(g), which is an air pollutant.

N2(g) + O2(g) + heat ↔ 2NO(g)

a. Higher engine temperatures are used to minimize carbon monoxide production. What effect does higher engine temperatures have on the production of NO(g)? Why?

b. What effect would high pressures have on the production of NO(g)? Why?

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Regents Review

Reactions Rates and Collision Theory Reaction rates depend on effective collisions. The more collisions, the higher the probability that a reaction will take place.

a. Describe how changes to each of the following will increase the rate of a reaction:

Temperature: __________________________________________________________________

Concentration of a solution: _______________________________________________________

Surface area of a solid: ___________________________________________________________

Pressure of a gas: _______________________________________________________________

Addition of a catalyst: ____________________________________________________________

b. In order for a reaction to take place, effective collisions are necessary. What are effective collisions?

Potential Energy Diagrams PE diagrams show the heat that a reaction has, gains, or loses, throughout the mechanism.

a. Label the following graph with the PE of the reactants, PE of the products, PE of the activated complex, activation energy of the forward reaction, activation energy of the reverse reaction, heat of reactions, and endothermic or exothermic.

b. Which of those values are changed when a catalyst is added?

c. How is the heat of reaction calculated?

Enthalpy and Entropy Enthalpy is the amount of heat lost or gained in a reaction. Entropy is the amount of disorder in a reaction.

a. Determine the enthalpy of the reaction that forms CO2 from its elements. ____________

b. What is the enthalpy of the reverse reaction on the question above? ____________c. What is the enthalpy of double the reaction in question a? ____________

d. Which phase has the most entropy? ____________22


e. How does temperature affect entropy? ________________________________________________

f. Name one phase change that would reduce the entropy of a system. ____________

LeChatelier’s Principle Reactions can be stressed by the addition of reactants, products, pressure or temperature. The reaction shifts away from a substance when that substance is added and toward that substance when it is taken. Increases in pressure increases the side with less moles due to less room.

12.6 kcal + H2(g) + I2(g) 2HI(g)

Stress Equilibrium Shift [H2] [I2] [HI]1. Add H2

2. Add I2

3. Add HI4. Remove H2

5. Remove I2

6. Remove HI7. Increase temperature8. Decrease temperature9. Increase pressure10. Decrease pressure

The binding of oxygen to hemoglobin (abbreviated Hb), giving oxyhemoglobin (HbO2) is partially regulated by the concentration of H+ and CO2 in the blood. Although the equilibrium is rather complicated it can be summarized as follows:

HbO2 + H+ + CO2 ↔ CO2HbH+ + O2

According to Le Chatelier’s principle, what would be the effect of each of the following on the equilibrium:

a. The production of lactic acid (contains H+) and CO2 in a muscle during exercise?

b. Inhaling fresh oxygen enriched air?

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chapters 17-18: kinetics and equilibrium class · web viewkey ideas collision theory states...

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