Chemistry 30 – Practice Final ExamName:________________________________

Unit 1 – Thermochemical Changes

Use the following information to answer the next question

Many insects and small animals have unique defence systems. Bombardier beetles fight off predators with a hot chemical spray. This spray consists of solutions of hydroquinone, C6H4(OH)2(aq), hydrogen peroxide, H2O2(aq), and enzymes which are secreted by the beetles’ glands.

Bombardier Beetle

Reaction Equations Related to Spray Formation

I 2 H2O(l) + O2(g) 2 H2O2(aq) ΔH = +189.2 kJ

II H2O(l) H2(g) + ½ O2(g) ΔH = + 285.8 kJ

III C6H4(OH)2(aq) C6H4O2(aq) + H2(g) ΔH = + 177.0 kJ

A chemical reaction that occurs in order to produce the hot chemical spray can be represented by the equation:

C6H4(OH)2(aq) + H2O2(aq) C6H4O2(aq) + 2 H2O(l)

hydroquinone quinone

1. The heat of reaction for the production of this hot chemical spray isA -489.2 kJB -203.4 kJC -82.4 kJD +12.2 kJ

Chemistry 30 – Practice Final Exam page 2

Numerical Response

1. A student heated a 120.0 g sample of H2O(l) from 21.0°C to 32.5°C by adding 5.93 kJ of energy. The student then used this data to calculate the specific heat capacity of water and compared it with the standard value. The experimental percentage difference was ______ %. (Record your three-digit answer in the numerical response section on the answer sheet.)

Use the following diagram to answer the next question

2. The energy barrier that must be overcome for the forward reaction to occur is called the i , and in the diagram above, it is the difference between ii .

The statement above is completed by the information in row

Row i iiA enthalpy change I and IIB enthalpy change I and IIIC activation energy I and IID activation energy I and III

Chemistry 30 – Practice Final Exam page 3

3. Which of the following is not true of both endothermic and exothermic reactions?A Energy is required to break bonds in the reactants.B Energy is produced as new bonds form in the products.C The amount of energy absorbed is less than the amount of energy released.D The energy is stored in chemical bonds as potential energy.

4. When 1.65 g of ethanal, CH3CHO(l) is burned in a calorimeter to produce H2O(l) and CO2(g), 44.7 kJ of heat energy is produced. According to this experimental data, the molar enthalpy of combustion of ethanal isA +1.52 x 103 kJ/molB -76.6 kJ/molC -165 kJ/molD -1.19 x 103 kJ/mol

Unit 2 – Electrochemical Changes

5. As H2S(g) forms S(s), according to the reaction:2 H2S(g) + O2(g) 2 H2O(g) + 2 S(s) , the oxidation number of sulfurA changes from 0 to -2 and sulfur is reduced.B changes from -2 to 0and sulfur is oxidized.C decreases by 2 and hydrogen sulfide acts as the reducing agent.D stays the same because the sulfur is neither oxidized nor reduced.

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At one time, an aqueous solution of formaldehyde called formalin, CH2O(aq), was used as a disinfectant and as a tissue preservative. Today, formalin is commonly used in the industrial preparation of plastics and resins.

Formalin can be produced by reacting methanol with acidified potassium dichromate, as represented by the following unbalanced equation.

_ CH3OH(l) + _ Cr2O72-(aq) + _ H+(aq) _ CH2O(aq) + _ Cr3+(aq) + _ H2O(l)

6. When the equation is balanced, it will read as follows:A CH3OH(l) + Cr2O7

2-(aq) + 14 H+(aq) CH2O(aq) + 2 Cr3+(aq) + 7 H2O(l)

B 3 CH3OH(l) + Cr2O72-(aq) + 14 H+(aq) 3 CH2O(aq) + 2 Cr3+(aq) + 7 H2O(l)

C 3 CH3OH(l) + Cr2O72-(aq) + 8 H+(aq) 3 CH2O(aq) + 2 Cr3+(aq) + 7 H2O(l)

D 3 CH3OH(l) + Cr2O72-(aq) + 8 H+(aq) 3 CH2O(aq) + 2 Cr3+(aq) + 8 H2O(l)

Chemistry 30 – Practice Final Exam page 4

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A student used an acidified 6.31 x 10-2 mol/L KMnO4(aq) solution to titrate 25.0 mL samples of Fe2+(aq) solution of unknown concentration. In the reactions, the Fe2+(aq) ion was oxidized to the Fe3+(aq) ion. The student completed five trials and summarized the data in a table.

trial number 1 2 3 4 5

final buret reading (mL)

17.55 35.65 26.40 42.65 16.85

initial buret reading (mL)

0.30 17.55 10.05 26.40 0.55

final colour purple purple pink pink pink

7. According to the student’s data, the concentration of Fe2+(aq) isA 0.206 mol/LB 0.218 mol/LC 0.213 mol/LD 0.223 mol/L

8. The half-reaction to which all other half-cell potentials are compared isA Li+(aq) + e– Li(s)

B Au3+(aq) + 3 e– Au(s)

C F2(g) + 2 e– 2 F–(aq)

D 2 H+(aq) + 2 e– H2(g)

Chemistry 30 – Practice Final Exam page 5

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Hydrogen-oxygen fuel cells have been used for years in spacecraft and more recently in small-scale power plants to generate electricity. Now, some governments and companies are working together to perfect this type of fuel cell for automobile use, and experiments are being conducted with operational prototypes. A diagram of a hydrogen-oxygen fuel cell is shown below.

Numerical Response

2. In the diagram above, the anode, the cathode, the electrolyte, and a product of the reaction are labeled, respectively, _____, _____, _____, and _____.

(Record your four-digit answer in the numerical-response section on the answer sheet.)

Chemistry 30 – Practice Final Exam page 6

Use the following information to answer the next two questions

Copper can be refined (purified) using an apparatus like the one shown below, which is a small-scale version of an industrial apparatus.

9. In this electrochemical cell, the purified copper sheet acts as theA anode and is the site where SO4

2-(aq) ions are oxidizedB cathode and is the site where SO4

2-(aq) ions are reducedC anode and is the site where Cu2+(aq) ions are oxidizedD cathode and is the site where Cu2+(aq) ions are reduced

Numerical Response

3. If the direct current power supply produces a steady 3.50 A current, then the time required to deposit 0.100 g of purified copper is _____ s.(Record your three-digit answer in the numerical response section on the answer sheet.)

Chemistry 30 – Practice Final Exam page 7

Unit 3 – Chemical Changes of Organic Compounds

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A student added a bromine solution to a hydrocarbon sample that contains an isomer of C7H14(l) in the absence of light. After shaking the sample, the student observed that the colour of the bromine solution changed from orange to colourless.

10. An interpretation that could be made from the student’s observation is that the hydrocarbon sample is i , and the IUPAC name of the sample could be ii .

The statement above is completed by the information in rowRow i ii

A saturated hept-2-eneB saturated cyclohexaneC unsaturated hept-2-eneD unsaturated cyclohexane

11. Which of the following is not a structural isomer of C7H14?A cyclo-octaneB 2-methylhex-3-eneC 2,2-dimethylpent-2-eneD trimethylbut-1-ene

12. When propan-1-ol and methanoic acid react, in the presence of an acid catalyst, the products areA methyl propanoate onlyB propyl methanoate onlyC methyl propanoate and waterD propyl methanoate and water

Chemistry 30 – Practice Final Exam page 8

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There are several methods of producing chloroethane, which can be used as a solvent and a refrigerant.

Reactants Type of Reaction1 ethene 5 condensation2 ethane 6 addition3 ethyne 7 elimination4 ethanol 8 substitution

Numerical Response

4. Match the reactants and type of reaction numbered above with the two methods of producing chloroethane below. (2 marks)

Method I

___________ + Cl-Cl H – C – C – Cl + HCl which is a(n) ___________ reaction. Reactant Product(Record in (Record in 1st column) 2nd column)

Method II

___________ + H – Cl H – C – C – Cl which is a(n) ___________ reaction. Reactant Product(Record in (Record in 3rd column) 4th column)

H H

H H

H H

H H

Chemistry 30 – Practice Final Exam page 9

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Numerical Response

5. Match the IUPAC name or the organic term numbered above with its descriptor below: (2 marks)Product name ________________ (Record in first column)

Reactant name ________________ (Record in second column)

Type of organic reaction ________________ (Record in third column)

Classification of product ________________ (Record in fourth column)

Unit 4 – Chemical Equilibrium Focussing on Acid-Base Systems

13. Sour pickles have pH of about 3.00. The [OH-] in a typical sour pickle isA 1.0 x 10-11 mol/LB 3.0 x 10-11 mol/LC 1.0 x 10-3 mol/LD 3.0 x 10-3 mol/L

Chemistry 30 – Practice Final Exam page 10

Use the following information to answer the next three questions

Coal and natural gas contain trace amounts of sulphur compounds, which when burned, may lead to acid rain pollution.

Reactions Related to Acid RainI 2 H2S(g) + 3 O2(g) 2 H2O(g) + 2 SO2(g)

II 2 SO2(g) + O2(g) 2 SO3(g)III SO2(g) + H2O(l) H2SO3(aq)IV SO3(g) + H2O(l) H2SO4(aq)

14. The equilibrium law expression for reaction I is

A

B

C

D

15. The conjugate base of H2SO3(aq) isA HSO3

–(aq)B SO3

2 –(aq)C OH–(aq)D H2O(l)

Use the following additional information to answer the next question

At 900 K, the equilibrium constant for reaction II is 13.0. The equilibrium concentrations are [SO2] = 0.361 mol/L and [SO3] = 0.840 mol/L

16. Given the values above, the calculated equilibrium concentration of O2(g) is A 0.179 mol/LB 0.416 mol/LC 2.40 mol/LD 5.59 mol/L

Chemistry 30 – Practice Final Exam page 11

17. Which of the following mixtures could act as buffer solutions?A HF(aq) and H2S(aq)B NaOH(aq) and HCl(aq)C Na2CO3(aq) and NH3(aq)D NaH2PO4(aq) and Na2HPO4(aq)

Use the following information to answer the next question

HNO2(aq) + HCO3 –(aq) NO2

–(aq) + H2CO3(aq)

18. In the reaction represented by the equation above, an amphiprotic species is i , and a conjugate acid-base pair is ii .

The statement above is completed by the information in rowRow i ii

A HNO2(aq) HNO2(aq) and H2CO3(aq)B HNO2(aq) H2CO3(aq) and NO2

–(aq)C HCO3

–(aq) H2CO3(aq) and HCO3 –(aq)

D HCO3 –(aq) HCO3

–(aq) and NO2–(aq)

Chemistry 30 – Practice Final Exam page 12

Use the following information to answer the next questionA student titrated an unknown sample an aqueous acid with an unnamed base. The data are graphed below:

19. The graph of the student’s titration data shows the titration of i acid with a strong base, and on the graph the equivalence point is indicated by point ii .

The statement above is completed by the information in row

Row i iiA weak IIB strong IIC strong IIID weak III

Written Response

2 questions: #1. analytical question#2 holistic question

volume of base (mL)

Chemistry 30 – Practice Final Exam page 13

Written Response – Question 1 (analytical)

Use the following information to answer this question

Fireball Horror of Aerosol Can BlastA housewife was engulfed in a fireball when she tried to separate two cans of hairspray that were taped together. She accidentally punctured one aerosol can with a knife as she cut the tape.

A jet of butane gas shot into her living room fireplace, ignited, then immediately exploded into a fireball that destroyed the room and enveloped the housewife in flames.

Melting point of butane -138.0°CBoiling point of butane -1.0°CHairspray use of butane solvent and propellant

1. a) Draw a structural diagram for butane (condensed or line structural diagram)

b) Write the balanced chemical equation for the combustion reaction that occurred and calculate the molar enthalpy of combustion for butane.

c) Instead of butane, non-flammable substances such as chlorofluorocarbons(e.g. CF2Cl2) are sometimes used as solvents and propellants for aerosol products. Select a position either for or against the continued use of butane as a propellant for aerosol cans. State one reason (not already given) to back up your answer.

Chemistry 30 – Practice Final Exam page 14

Written Response – Question 2

2. The Haber-Bosch process for the industrial production of ammonia involves the equilibrium

N2(g) + 3 H2(g) 2 NH3(g) + 92.2 kJ

In a laboratory experiment designed to study this equilibrium, a chemical engineer injects 0.20 mol of N2(g) and 0.60 mol of H2(g) into a 1.0 L flask at 500°C. She records her analysis of the contents of the flask at 5 s intervals in the table shown.

Time (s)Concentration (mol/L)

N2(g) H2(g) NH3(g)0 0.20 0.60 0.005 0.14 0.42 0.1210 0.11 0.33 0.1815 0.10 0.30 0.2020 0.10 0.30 0.2025 0.10 0.30 0.20

Analyze the data. Your response should include:• a plot of the concentrations of N2(g), H2(g), and NH3(g) versus time on the grid

provided below, including appropriate title• the time required to reach equilibrium• the equilibrium constant for the reaction• two methods, other than increasing reactant concentrations, that could increase the

yield of ammonia

more space to answer rest of question on next page.

Chemistry 30 – Practice Final Exam page 15

Written Response – Question 2 continued