Chemistry 3202Mid Year Exam 2006Page 1 of 17

CHEMISTRY 3202

MID-YEAR EXAMINATION

PART 1 – MULTIPLE CHOICE QUESTIONS

January 2006

GENERAL INSTRUCTIONS

This is Part 1 of a two part exam. It consists of 40 multiple choice items. The value of this part is 40 points. Additional directions are provided on the cover page of Part 2.

Please use a blue or black ink pen to write your answers neatly in the spaces provided on answer form (Last page in this part of the exam).

The duration of the two part exam is two (2) hours. Part 1 should be completed in one (1) hour.

Data tables are provided on pages 2 and 3.

Please submit all test materials to your supervisor upon completion of the exam. This includes any paper used for workings, etc.

Please attempt all items.

Chemistry 3202Mid Year Exam 2006Page 1 of 19

Multiple Choice: Choose the response which BEST completes the item and write the letter in the appropriate space on the answer sheet provided at the end of this section. Total Value = 40 points

1.What is meant by the term open system?

A.the system is open to the flow of heat only

B.the system is open to the flow of matter only

C.the system is open to the flow of matter and heat

D.the system is open to the universe

2.Which best describes the direction of heat flow and the type of heat change that occurs when an ice cube (system) is placed in water (surroundings) at 20°C?

Direction of heat flowHeat change of system

A.from ice cube to water endothermic

B.from ice cube to water exothermic

C.from water to ice cube endothermic

D.from water to ice cube exothermic

3.The water temperature in a small stream went from 15°C to 18°C on a hot sunny day. Assuming that none of the water underwent a phase change, what can be said about the water?

A.its heat capacity increased

B.its kinetic energy increased

C.its potential energy increased

D.its specific heat capacity increased

4.Which change is exothermic?

A.dry ice (solid CO2) sublimates at SATP

B.methanol vaporizes on a bench top

C.water vapour solidifies on a cold surface

D.zinc metal melts at 420°C

5.One gram of scandium gains 0.557 J when heated from 21°C to 22°C. What does the 0.557 value represent?

A.the molar heat of fusion

B.the potential energy increase

C.the specific heat capacity

D.the strength of metallic bonds

6.A piece of red hot iron is added to an insulated container of cold water. Assuming that iron is the system and water is the surroundings, which statement is true?

7.In the lab, a student dissolved ammonium nitrate crystals in a beaker of water and noticed that the water temperature changed from 28.2°C to 14.0°C. What is a suitable interpretation of the student’s observation?

A.dissolving ammonium nitrate in water is an endothermic process

B.dissolving ammonium nitrate increases the kinetic energy of the water

C.solid ammonium nitrate has more potential energy than the aqueous form

D.the value for the molar heat of solution for ammonium nitrate has a negative sign

8. How much energy is needed to increase the temperature of 525 mL of water from 10.3°C to 99.9°C?

A.22.7 kJ

B.197 kJ

C.220 kJ

D.242 kJ

9. What mass of tin is warmed from 20.0°C to 35.0°C upon absorbing 100.0J?

cSn = 0.213 J/(g°C)

A.0.0888 g

B.1.42 g

C.31.3 g

D.319 g

cmetal () / 0.900 / 0.385 / 0.129 / 0.444

10.10.0 g pieces of aluminum, copper, gold, and iron, each at 100.0°C, are added to beakers containing equal amounts of water at 20.0°C. Which metal will cause the largest temperature change in the water?

A.aluminum

B.copper

C.gold

D.iron

11.Which region of the graph shows this change?

A.1  2

B.2  3

C.3  4

D.4  5

12.What does a molecule possess because of its position relative to other molecules?

A.enthalpy

B.heat capacity

C.kinetic energy

D.thermal energy

13. Ammonia’s molar enthalpy of vaporization is 23.4 kJ/mol. What is the change in enthalpy associated with condensing 0.340 mol of ammonia?

A.-68.8 kJ

B.- 7.96 kJ

C.+ 7.96 kJ

D.+ 68.8 kJ

Use this equation for the formation of water at SATP conditions to complete the next two items:

14.What is the standard molar heat of formation of water?

A. -483.6 kJ/mol

B.-241.8 kJ/mol

C.+241.8 kJ/mol

D. +483.6 kJ/mol

15.Which statement regarding theformation of water is TRUE?

A.burning 2.00 g of hydrogen produces 483.6 kJ of heat

B.hydrogen gas and oxygen gas have more kinetic energy than water

C.water has less potential energy than hydrogen gas and oxygen gas

D.water undergoes a physical change

16.Heat is released from liquid aluminum at its freezing point (660°C) until it completely solidifies. What happens to the forces of attraction between aluminum atoms and thepotential energy of the aluminum atoms?

Forces of Attraction / Potential Energy
A. / decrease / decrease
B. / decrease / increase
C. / increase / decrease
D. / increase / increase

17.Based on the information below, what is the molar heat of combustion of methanol?

A.- 1116.2 kJ/mol

B.-638.0 kJ/mol

C.- 396.2 kJ/mol

D.+396.2 kJ/mol

18.Given these equations,

what is the enthalpy change for this reaction?

A.-632 kJ

B.- 316 kJ

C.+ 316 kJ

D.+ 632 kJ

19.Based on the bond energies provided, what is the enthalpy change for this reaction?

A.-247 kJ

B.-185 kJ

C.+185 kJ

D.1111 kJ

Nutrition Information
per 2 cookie serving ……………....…31 g
Energy………………...…160 Cal / 670J
Protein…………………………….…2.0 g
Total Fat...... 8.3 g
Total Carbohydrate …………………...19 g

20.What is the fuel value of chocolate chip cookies given the nutrition information from the product label?

A.0.046 kJ/g

B.22 kJ/g

C.43 kJ/g

D.670 kJ

21.Which statements regarding the collision theory of reaction rates are correct?

I.explains the expansion of matter when heated.

II.assumes that reaction rate depends on the frequency at which reactants collide.

III.assumes that reactants must be in correct orientation to react.

IV.assumes that only collisions with energy at or above the activation energy are successful.

A.I, II, and III are correct

B.I, III, and IV are correct

C.II, III, and IV are correct

D.All four statementsare correct

22.Why does a higher concentration of reactants make a reaction faster?

A.Collisions occur with greater energy.

B.The activation energy for the reaction is decreased.

C.There are more collisions per second and the collisions are of greater energy.

D.There are more collisions per second.

23.In each trial of an experiment, the mass of Zn and the volume of HCl(aq) are held constant but the form of Zn and the concentration of HCl(aq) may differ. What are the rates of reactions from fastest to slowest?

Fastest  slowest

A.trial #1  trial #2  trial #3

B.trial #3  trial #2  trial #1

C.trial #2  trial #1  trial #3

D.trial #3  trial #1  trial #2

24.The reaction of dinitrogen pentoxide with water has an activation energy of 43 kJ. Which diagram best represents this reaction?

A. / / C. /
B. / / D. /

25. What effect does a catalyst have on a reaction?

A.It changes the H of a reaction.

B.It decreases the potential energy of the products.

C.It increases the kinetic energy of the reaction.

D.It provides an alternate reaction mechanism with loweractivation energy.

26.The decomposition of dinitrogen pentaoxide was studied at 50°C and at75°C. It was found that the reaction rate at 75°C was greater than the reaction rate at 50°C. What accounts for this observation?

A.The activation energy increases with increasing temperature

B.The number of molecules with enough energy to reactincreases with increasing temperature.

C.The molar enthalpy increases with increasing temperature

D.The concentration of a gas increases with increasing temperature

27.In the diagram to the right, what indicates the activation energy for the reverse reaction?

A. A

B. B

C. C

D. D

Use the diagram to the right to answer questions 28 and 29.

28.Which interpretation of the diagram to the right is correct?

A.the activation energy for step 3 is 10 kJ

B.the forward reaction is endothermic

C.the heat of reaction is +20 kJ

D.the rate determining step is step 3

29.Which mechanism matches the potential energy diagram to the right?

A.A + B  C + Dfast

C + A  B + F slow

B.A + B  C + Dslow

C + A  B + Ffast

C.A + B  C + Dfast

C + A  B + Fslow

F + E  G fast

D.A + B  C + Dslow

C + A  B + Ffast

F + E  G fast

Use these equations to complete the next two items.

30.What is the catalyst in the mechanism?

A. A

B. B

C. C

D. D

31.Increasing the concentration of which reactant would NOT increase the rate of reaction?

A. A

B. B

C. C

D. D

32.For a system at equilibrium, which statement is FALSE?

A.the system must be closed

B.the reaction must be reversible

C.the concentrations of reactants and products are equal

D.opposing reactions occur at equal rates

33.What is the effect of adding O2 (g) to the system at constant volume and temperature?

A.a decrease in the concentration of NO2(g)

B.an increase in the concentration of NO(g)

C.an increase in the concentration ofNO2(g)

D.no change in the concentration of NO(g)

34.What condition will maximize the amount of NO2 (g) at equilibrium?

A.high pressure and high temperature

B.high pressure and low temperature

C.low pressure and high temperature

D.low pressure and low temperature

35.Which factor changes the size of the equilibrium constant?

A.activation energy of the forward reaction

B.change in temperature

C.changes in concentrations of the reactants or products

D.addition of a catalyst

36.Which is the correct form of the equilibrium constant expression for the reaction?

A.C.

B.D.

37.If the system below has reached equilibrium, and the equilibrium concentration of COCl2 = 0.273 mol/L and CO = 0.111 mol/L, what is the equilibrium concentration of Cl2?

A.5.5 x 10-2 mol/L

B.0.13 mol/L

C.0.20 mol/L

D.3.0 x 102 mol/L

38.Which equilibrium constant value indicates an equilibrium system that has a large concentration of products and a relatively small concentration of reactants?

A.4.5  10-8

B.6.0  10-2

C.1.0

D.2 .0 x 104

Compounds A, B, and C react according to the equation:

If the equilibrium concentrations are: [A] = 0.855 M, [B] = 1.23 M, and [C] = 1.75 M, what is the value of K for this reaction?

A.0.309

B.0.601

C.1.66

D.3.24

40.Which substance is produced as a result of a reaction catalyzed by nitrogen monoxide from automobile exhaust?

Acid rain
Ground level ozone
PCB’s
CFC’s

Chemistry 3202Mid Year ExamPage 1 of 19

Name:______School______

CHEMISTRY 3202 MID-YEAR EXAM

WINTER 2006

Please separate this page from the remainder of the test and add it to your answer sheets from Section 2. It should be the first page of your scanned test paper.

Be sure to write your name and your school name on ALL written answer pages and be sure to number your pages.

1. ______11. ______21. ______31. ______

2. ______12. ______22. ______32. ______

3. ______13. ______23. ______33. ______

4. ______14. ______24. ______34. ______

5. ______15. ______25. ______35. ______

6. ______16. ______26. ______36. ______

7. ______17. ______27. ______37. ______

8. ______18. ______28. ______38. ______

9. ______19. ______29. ______39. ______

10. ______20. ______30. ______40. ______

CHEMISTRY 3202

MID-YEAR EXAMINATION

PART 2 – Constructed Response Items

January 2006

GENERAL INSTRUCTIONS

This is Part 2 of a two part exam. It consists of eight (8) major items. The total value of this part of the exam is 40 points.

Please use a blue or black ink pen to write your answers neatly in the spaces provided on the test paper. There should be sufficient space for your responses; however, if more space is required use an additional unlined 8 ½ x 11” sheet of copy paper and label the responses appropriately. On the main test paper, indicate that the response is continued on the extra page.

The full exam (Parts 1 and 2) should be completed in a two (2) hour examination period. Part 2 should be completed in one (1) hour.

Data tables were providedin Part 1.

Please submit all test materials, including sheets containing rough workings, to your supervisor upon completion of the exam.

Please attempt all items.

Part 2 -Constructed Response Items: Write a detailed response for each item in the space provided. Show all calculations. Value = 40 points

Value

(3)41.(a)Draw and label a cooling curve to show the changes that occur as 250.0g of water at 20.0°C cools to ice at -10.0°C. Be sure to label the axes and indicate the appropriate state of matter for each section of the curve.

(2)41.(b)For each section of the curve in 41 (a), describe the energy changes that water molecules undergo as they cool from 20.0°C to -10.0°C

(1)41.(c)In terms of intermolecular forces, describe what happens when water freezes.

(4)41.(d)Calculate the total energy change associated with cooling 250.0 g of water in 41(a) above from 20.0°C to ice at -10.0°C

42. a)Sodium metal reacts with water according to the equation:

A 0.75 g piece of sodium metal is added to a simple calorimeter that holds 200.0 mL of water at 19.84°C. The sodium metal reacts with the water to give a final temperature of 48.55°C.

(1)i)Identify the system and the surroundings in this calorimetry experiment.

(4)ii)Calculate the molar heat of reaction (in kJ/mol) with respect to the sodium metal.

(2)42. b) List two assumptions associated with simple calorimetry.

(3)43.Calculate the enthalpy change (in kJ) for the reaction of hydrogen with 1,3-butadiene to produce butane. (Show all workings)

Given thermochemical equations:

(3)44.With clear references to the collision theory, discuss three (3) specific ways you could increase the rate of this chemical reaction.

(1)45. (a)Complete step 2 for the reaction mechanism

Step 1:

Step 2: ______

overall:

(2)(b)If the reaction rate above does not change when the concentration of Fe3+ is increased, identify the rate-determining step. Explain your answer.

(6)46.Consider the equilibrium in a closed container:

What effect, if any, will each action have on the position of equilibrium? In each case, state the direction of any shift in equilibrium, and give your reasons in one sentence.

a)adding more Fe(OH)3(s)

b)raising the temperature

c)adding a catalyst

(4)47.Consider theequilibrium:

A 2.0 L container is filled with 0.15 mol N2, 0.15 mol O2 and 0.050 mol NO. Does the [NO] increase or decrease as equilibrium is established? Support your answer with appropriate calculations.

(4)48.Consider the equilibrium:

An initial mixture composed of 0.040 mol of SO2 and 0.0250 mol of O2 were put in an empty 2.00 L reaction vessel. After equilibrium was reached, the concentration of SO3 was 0.014 mol/L. What is the equilibrium constant K for this system?