THE UNIVERSITY OF CALGARY

FACULTY OF SCIENCE

FINAL EXAMINATION

CHEMISTRY 209

Date: Tuesday, April 25th, 2017 Time: 3:30pm – 6:30pm

First Name: Last Name:

When you start the test, please fill in your ID# on the next page.

Please circle your lecture section:

L01 Dr. Mozol L02 Dr. Musgrove Richer TR 12:30 PM TR 8:00 AM

• Examination Policies: • This is a closed-book examination. The use of camera devices, MP3 players, headphones, or wireless access

devices such as cell phones, smartwatches, etc. during the examination will not be allowed. • Only non-programmable Schulich-approved calculators are permitted. • A Chemical Data Sheet is provided at the end of the exam and can be removed for quick reference. • All questions must be answered to obtain full marks. The answers to the multiple-choice section must be entered

on the optical score sheet within the 3-hour exam time. • Work on page backs will not be graded unless it is clearly indicated to do so within the space provided for

answering each question.

This test consists of 19 multiple choice questions worth 2 marks each (total 38 marks) and 6 long answer questions (total 33 marks). The total value for the test is 71 marks.

The exam has 17 pages (including this one) – please make sure you have all 17 pages.

AT THE END OF THE EXAMINATION, HAND IN THE OPTICAL SCORE SHEET AND THE ENTIRE EXAM PAPER.

CHEM 209 W2017 Page 2 of 17

SECTION I – Machine-graded section (Total value 38)

To be answered on Optical Score Sheet

1. How many hydrogen atoms are in exactly 2 g of hydrazinium sulfate, N2H6SO4?

a. 5.55×10-24 atoms

b. 9.25×1021 atoms

c. 9.25×10-25 atoms

d. 5.56×1022 atoms

2. Based on the plot on the right, which of the following statements is correct?

a. The initial rate for the reaction is 1.3 M s-1.

b. The average rate of the disappearance of A

during the entire duration of the reaction is

0.25 M s-1

c. The appearance of B at 8 seconds would be

0.14 s-1

d. The rate of the reaction cannot be

determined using the plot given

Write your ID# here: Sec II - Q1 Sec II - Q2 Sec II - Q3 Sec II - Q4 Sec II – Q5 Sec II – Q6

Do not write in the shaded part. For marking only.

CHEM 209 W2017 Page 3 of 17

3. For the dimerization of butadiene:

2 𝐶4𝐻6 (𝑔) ⟶ 𝐶8𝐻12 (𝑔) Rate = k [𝐶4𝐻6]

The units of the reaction rate are:

a. M-1 s-1

b. s-1

c. M2s-1

d. M s-1

4. The reaction: 2 𝑁𝑂2(𝑔) ⟶ 2𝑁𝑂 (𝑔) + 𝑂2 (𝑔)

Is suspected to be second order in NO2. Which of the following plots would provide a linear graph that could be used to confirm this hypothesis?

a. A plot of [NO2] against time

b. A plot of rate against [NO2]

c. A plot of ln[NO2] against time

d. A plot of [NO2]-1 against time

5. The catalyzed gas-phase decomposition of ammonia (NH3) on a metal surface produces nitrogen and hydrogen gases: 𝑁𝐻3 (𝑔) ⟶ 1

2𝑁2 (𝑔) + 3

2𝐻2 (𝑔) rate = k

Which of the plots below would be expected for a plot of rate as a function of concentration?

a. b. c. d.

Incr

easin

g Ra

te

Incr

easin

g Ra

te

Increasing concentration Increasing concentration Increasing concentration Increasing concentration

Incr

easin

g Ra

te

Incr

easin

g Ra

te

CHEM 209 W2017 Page 4 of 17

6. Based on the reactions and equilibrium constants given below, determine the value of the equilibrium constant

(Kf) for the formation of the soluble PbI42- complex:

𝑃𝑏𝐼2 (𝑠) ⇌ 𝑃𝑏2+ (𝑎𝑞) + 2 𝐼− (𝑎𝑞) 𝐾𝑠𝑝 = 7.9×10−9

𝑃𝑏𝐼2(𝑠) + 2 𝐼− (𝑎𝑞) ⇌ 𝑃𝑏𝐼42− (𝑎𝑞) 𝐾 = 2.37×10−4

𝑃𝑏2+ (𝑎𝑞) + 4 𝐼− (𝑎𝑞) ⇌ 𝑃𝑏𝐼42− (𝑎𝑞) 𝐾𝑓 = ? ?

a. 3.0×104

b. 3.3×10-5

c. 1.9×10-12

d. 1.4×10-1

7. A reaction vessel is prepared by putting 0.2 mol of H2S (g) and 0.05 mol of NH3 (g) into a sealed 1.0 L vessel

containing 0.05 mol of ammonium hydrosulfide. Based on the reaction given below, will there be a change in the

amounts of ammonium hydrosulfide in the flask after waiting for some time?

𝑁𝐻4𝐻𝑆 (𝑠) ⇌ 𝐻2𝑆 (𝑔) + 𝑁𝐻3 (𝑔) 𝐾𝐶 = 0.11

a. The amount of NH4HS will increase in the flask.

b. The amount of NH4HS will decrease in the flask.

c. The amount of NH4HS in the flask will stay the same.

d. The change cannot be determined, since NH4HS is a solid.

8. A solution made by dissolving 0.1 mol of acetic acid in 1.0 L of water is 4.1% dissociated. Which of the

modifications below would cause the % dissociation of the acetic acid in the container to increase?

(Ka for acetic acid is 1.8×10-5.)

a. Adding 0.01 mol HCl

b. Adding 200 mL of water

c. Adding 0.01 mol of acetic acid

d. Decreasing the temperature from 25°C to 5°C

CHEM 209 W2017 Page 5 of 17

9. What is the pH of a 0.10 M solution of NaF? (Ka for HF = 6.8×10-4)

a. 2.08

b. 5.92

c. 8.08

d. 11.92

10. Which of the following mixtures will create a solution with the largest buffer capacity?

a. 1.0 L of 0.2 M NH3 with 1.0 L of 0.2 M NH4Cl

b. 1.0 L of 0.5 M NH3 with 1.0 L of 0.5 M HCl

c. 1.0 L of 0.6 M NH4Cl with 1.0 L of 0.3 M NaOH

d. 0.5 L of 0.3 M NH3 with 0.5 L of 0.3 M NH4Cl

11. What is the pH of a solution created by mixing 500. mL of a 0.10 M HOBr solution with 250. mL of a 0.20 M

NaOBr solution? (Ka for HOBr = 2.3×10-9)

a. 4.66

b. 8.63

c. 5.36

d. 9.34

12. Which of the ground-state atoms in the table below have their magnetic behavior identified correctly?

a. I and III only

b. II only

c. All atoms have their magnetic behaviour correctly identified

d. No atoms have their magnetic behaviour correctly identified

Atom Classification

I. Mg paramagnetic

II. Si diamagnetic

III. Br diamagnetic

CHEM 209 W2017 Page 6 of 17

Use the standard reduction potentials below to answer the next two questions.

Reduction half-reaction E° (V) 𝐶𝑎2+ (𝑎𝑞) + 2 𝑒− ⇌ 𝐶𝑎 (𝑠) -2.87

𝑁𝑎+ (𝑎𝑞) + 𝑒− ⇌ 𝑁𝑎 (𝑠) -2.71 𝐴𝑙3+ (𝑎𝑞) + 3 𝑒− ⇌ 𝐴𝑙(𝑠) -1.66

𝑀𝑛2+ (𝑎𝑞) + 2 𝑒− ⇌ 𝑀𝑛 (𝑠) -1.18 𝐶𝑢2+ (𝑎𝑞) + 2 𝑒− ⇌ 𝐶𝑢 (𝑠) +0.15

𝐴𝑔+ (𝑎𝑞) + 𝑒− ⇌ 𝐴𝑔 (𝑠) +0.80

13. Which metal could be used to create a sacrificial anode for an aluminum pipe? a. Ag

b. Cu

c. Mn

d. Ca

14. Which species listed is the strongest oxidizing agent?

a. Ca2+

b. Ag+

c. Ca

d. Ag

15. Which of the representations for the arrangement of electrons in the ground-state atoms below is incorrect?

Atom Orbital Diagram or Electron Configuration

a. C

b. Mg

[Ne] 3s2

c. Cl

d. Sn

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p2

CHEM 209 W2017 Page 7 of 17

Use the molecular structure of CH3NCH2 on the right to answer Questions 16 and 17.

This structure does not show lone pairs, however all bonds and non-zero formal charges are shown.

16. Which of the choices below correctly identifies the electron-pair geometries of the atoms indicated?

C1 N C2

a. Tetrahedral Trigonal planar Trigonal planar b. Trigonal pyramidal Linear Tetrahedral c. Square planar Trigonal pyramidal Trigonal pyramidal d. Tetrahedral Bent Tetrahedral

17. Which of the choices below correctly identifies the hybridization of the indicated atoms?

C1 N C2

a. sp4 sp2 sp3 b. sp2 sp3 sp3 c. sp3 sp2 sp2 d. sp sp sp2

18. Which of the following sets of atoms correctly identifies the type of bonding that would occur between them?

a. II and III only

b. III only

c. All have the type of bonding correctly identified

d. None have the type of bonding correctly identified

Atom 1 Atom 2 Type of Bonding

I. S S Metallic

II. S O Covalent

III. S Na ionic

CHEM 209 W2017 Page 8 of 17

19. The Lewis diagrams for several molecules are shown below. Which of the molecules would be nonpolar?

a.

b.

c.

d.

END OF MULTIPLE CHOICE SECTION

Make sure you have “bubbled in” on the Optical Scoring Sheet:

• Answers for all 19 questions • Your name and ID number

• The Version Number (on the exam cover page)

CHEM 209 W2017 Page 9 of 17

SECTION II: Written Answers: To be graded manually (Total value 33 marks) For full marks, show all your work.

1. [3 marks]

The reaction energy profile on the right describes the reaction:

2 𝐻2𝑂2(𝑎𝑞) ⟶ 2𝐻2𝑂 (𝑎𝑞) + 𝑂2 (𝑎𝑞)

a. Sketch the reaction energy profile for the same reaction, if the temperature of the reaction is increased. Identify the products, reactants, and any intermediates present on your sketch.

b. Sketch the profile if the catalyst I_

is added, changing the mechanism to:

𝐻2𝑂2(𝑎𝑞) + 𝐼− (𝑎𝑞) ⟶ 𝐻2𝑂 (𝑎𝑞) + 𝐼𝑂− (𝑎𝑞) 𝑓𝑎𝑠𝑡

𝐻2𝑂2(𝑎𝑞) + 𝐼𝑂− (𝑎𝑞) ⟶ 𝐻2𝑂 (𝑎𝑞) + 𝑂2 (𝑎𝑞) + 𝐼− (𝑎𝑞) 𝑠𝑙𝑜𝑤 Identify the products, reactants, and any intermediates present on your sketch.

2 H2O + O2

2 H2O2

Pote

ntia

l Ene

rgy

Reaction Coordinate

Pote

ntia

l Ene

rgy

Reaction Coordinate

Pote

ntia

l Ene

rgy

Reaction Coordinate

CHEM 209 W2017 Page 10 of 17

2. [6 marks] a. In the table below, indicate whether a 0.10 M solution of each compound will produce a solution that is

acidic, basic, or neutral.

Compound Acidic? Basic? Neutral? Example: HCl X

NaOBr

NaClO4

NH4Cl

KF

Ca(OH)2

b. Rank the relative pH of the solutions below, from lowest pH to highest:

0.10 M NaF 0.10 M NaHCOO 0.10 M NaCl 0.10 M CH3COOH

Ka for HF = 6.8×10-4 Ka for HCOOH = 1.8×10-4 Ka for HCl = 1.3×106 Ka for CH3COOH = 1.8×10-5 Rank –

1: lowest pH,

4: highest pH

c. You have a series of beakers, each containing 100 mL of a different solution. If you added nickel (II) hydroxide (Ni(OH)2) to each of the beakers, rank them in order of the relative solubility of the Ni(OH)2 in each:

𝑁𝑖(𝑂𝐻)2 (𝑠) ⇌ 𝑁𝑖2+ (𝑎𝑞) + 2 𝑂𝐻− (𝑎𝑞) 𝐾𝑠𝑝 = 6.0×10−16

Flask A Flask B Flask C Flask D Flask E

Rank –

1: most soluble,

5: least soluble

0.1 M HNO3

0.01 M Ni(Cl)2

1.0 M NH3

RO Water

0.1 M Ni(Cl)2

CHEM 209 W2017 Page 11 of 17

3. [4 marks] a. A solution is made by mixing 10.0 mL of 1.0 M acetic acid with 0.82 g of sodium acetate (NaCH3COO). The Ka

of acetic acid is 1.8×10-5. What is the pH of this solution?

b. 10 mL of 0.1 M HCl is added to the solution from part (a). What is the pH of the mixture after adding HCl?

c. What is the molar solubility of nickel (II) hydroxide (Ni(OH)2) in pure water? The Ksp for Ni(OH)2 is 6.0×10-16. [2 marks]

CHEM 209 W2017 Page 12 of 17

4. An electrochemical cell is prepared according to the following diagram: [5 marks]

a. If the cell is prepared under standard conditions, what reading will the voltmeter display (assuming the leads are connected correctly)?

b. Use the boxes on the diagram to label the ANODE and the CATHODE for this cell.

c. Give the balanced reaction that is taking place in the electrochemical cell.

d. If the Cu2+ concentration is decreased to 0.100 M (leaving all other conditions the same), what will the new voltmeter reading be?

Reduction half-reaction E° (V) 𝐴𝑙3+ (𝑎𝑞) + 3 𝑒− ⇌ 𝐴𝑙(𝑠) -1.66

𝐶𝑢2+ (𝑎𝑞) + 2 𝑒− ⇌ 𝐶𝑢 (𝑠) +0.15

CHEM 209 W2017 Page 13 of 17

5. [12 marks] a. Draw the complete orbital diagrams for the ground-state atoms of Al and O:

Al

O

b. Complete the table below showing the orbitals off the specified electrons in an atom of Al and O. • gridlines have been given to help you illustrate relative size. • include axes to show orientation in 3-dimensional space.

The lowest energy core electrons in an atom of Al

The lowest energy valence electrons in an atom of O

The highest energy valence electron in an atom of Al

Shape of VALENCE

orbital

Name of the

orbital drawn above

c. Al and O make the ionic compound Al2O3. Based on this information, complete the table below.

Identity of the: Complete electron configuration of the ion

Cation: (include its charge)

Anion: (include its charge)

CHEM 209 W2017 Page 14 of 17

d. Consider the atoms hydrogen (H), oxygen (O), fluorine (F), and sodium (Na). [3 marks]

In order of increasing first ionization energy: < < <

Placed in order of increasing size: < < <

Placed in order of increasing electron affinity: < < < (least exothermic to most exothermic):

e. Draw the Lewis structures for the atoms and molecules below:

Lewis dot symbols

Lewis dot symbols

Lewis Structure for HOF:

Lewis Structure for: NaOF

H Na

O F

CHEM 209 W2017 Page 15 of 17

6. [3 marks] Based on the Lewis diagrams for NH3 and NH4

+ given below, draw their VSEPR diagrams, and predict their molecular shape.

VSEPR (3D) diagram: NH3 VSEPR (3D) diagram: NH4+

The molecular shape of the NH3 molecule is _______________________________________________

The molecular shape of the NH4+ ion is ____________________________________________________

END OF LONG ANSWER SECTION

Make sure you have put your FULL NAME on the front cover and STUDENT ID on the first page of the exam.

Check that your Optical Score “bubble” sheet is properly filled in.

CHEM 209 W2017 Page 17 of 17

Data Sheet – CHEM 209 1

1A

Legend: Periodic Table 18

8A

1

H 1.008

2 2A

1

H 1.008

Å Atomic number (Z) Å Atomic symbol Å Atomic mass (amu)

13 3A

14 4A

15 5A

16 6A

17 7A

2

He 4.003

3

Li 6.941

4

Be 9.012

5

B 10.81

6

C 12.01

7

N 14.01

8

O 16.00

9

F 19.00

10

Ne 20.18

11

Na 22.99

12

Mg 24.31

3 4 5 6 7 8 9 10 11 12

13

Al 26.98

14

Si 28.09

15

P 30.97

16

S 32.07

17

Cl 35.45

18

Ar 39.95

19

K 39.10

20

Ca 40.08

21

Sc 44.96

22

Ti 47.88

23

V 50.94

24

Cr 52.00

25

Mn 54.94

26

Fe 55.85

27

Co 58.93

28

Ni 58.69

29

Cu 63.55

30

Zn 65.38

31

Ga 69.72

32

Ge 72.59

33

As 74.92

34

Se 78.96

35

Br 79.90

36

Kr 83.80

37

Rb 85.47

38

Sr 87.62

39

Y 88.91

40

Zr 91.22

41

Nb 92.91

42

Mo 95.94

43

Tc (98)

44

Ru 101.1

45

Rh 102.9

46

Pd 106.4

47

Ag 107.9

48

Cd 112.4

49

In 114.8

50

Sn 118.7

51

Sb 121.8

52

Te 127.6

53

I 126.9

54

Xe 131.3

55

Cs 132.9

56

Ba 137.3

57*

La 138.9

72

Hf 178.5

73

Ta 180.9

74

W 183.9

75

Re 186.2

76

Os 190.2

77

Ir 192.2

78

Pt 195.1

79

Au 197.0

80

Hg 200.6

81

Tl 204.4

82

Pb 207.2

83

Bi 209.0

84

Po (209)

85

At (210)

86

Rn (222)

87

Fr (223)

88

Ra 226.0

89**

Ac (227)

104

Rf (261)

105

Ha (262)

106

Sg (263)

107

Ns (262)

108

Hs (265)

109

Mt (266)

110

Uun (269)

111

Uuu (272)

Lanthanides * 58

Ce 140.1

59

Pr 140.9

60

Nd 144.2

61

Pm (145)

62

Sm 150.4

63

Eu 152.0

64

Gd 157.3

65

Tb 158.9

66

Dy 162.5

67

Ho 164.9

68

Er 167.3

69

Tm 168.9

70

Yb 173.0

71

Lu 175.0

Actinides ** 90

Th 232.0

91

Pa 231.0

92

U 238.0

93

Np 237.0

94

Pu (244)

95

Am (243)

96

Cm (247)

97

Bk (247)

98

Cf (251)

99

Es (252)

100

Fm (257)

101

Md (258)

102

No (259)

103

Lr (260)

Strong Acids: HCl, HBr, HI, HNO3, H2SO4, HClO4 Strong Bases: Hydroxides of Group 1 (Li to Cs) and Group 2 (Ca, Sr, Ba)

Constants: Conversion Factors: Gas Constant: R = 0.08205 L·atm·mol-1·K-1 1 J = 1 kg·m2·s-2 = 8.314 L·kPa·mol-1·K-1 = 8.314 J·mol-1·K-1 T (K) = T (°C) + 273.15 = 0.08314 L·bar·mol-1·K-1 1 Pa = 1 kg·m-1·s-2 = 10-5 bar Avogadro’s number: NA = 6.022×1023 mol-1 1 L·atm = 101.3 J Faraday’s Constant: F = 96 485 C/mol electrons 1 atm = 760.0 torr = 101.3 kPa = 760.0 mm Hg = 1.013 bar Planck’s Constant: h = 6.626×10-34 J·s 1 L = 10-3 m3

Speed of Light: c = 2.998×108 m·s-1 1 C = 1 J/V 1 A = 1 C/s Rydberg Constant: R = 1.096776×107 m-1 STP conditions: 0°C, 100 kPa Factoring Rydberg Constant: RH = R·h·c = 2.18×10-18 J Electrochemical standard state: 100 kPa, 1 M, (25°C unless stated otherwise)

[𝐴]𝑡 = −𝑘𝑡 + [𝐴]0 ln[𝐴]𝑡 = −𝑘𝑡 + ln[𝐴]0 𝑃𝑉 = 𝑛𝑅𝑇 𝐸° = 𝐸𝑐𝑎𝑡ℎ𝑜𝑑𝑒

° − 𝐸𝑎𝑛𝑜𝑑𝑒° 𝑐 = 𝜆𝜈

ln ([𝐴]0[𝐴]𝑡

) = 𝑘𝑡 1

[𝐴]𝑡= 𝑘𝑡 +

1[𝐴]0

𝐾 = 𝐾𝐶(𝑅𝑇)∆𝑛

𝐸 = 𝐸° −0.0592

𝑛𝑒log 𝑄

𝐸 = ℎ𝜈

𝑝𝐻 = − log[𝐻+] 𝐸 = 𝑚𝑐2

𝑡1 2⁄ =[𝐴]0

2𝑘 𝑡1 2⁄ =

0.693𝑘

𝐾𝑤 = 𝐾𝑎 ∙ 𝐾𝑏 𝐸° =

𝑅𝑇𝑛𝐹

ln 𝐾

1𝜆

= 𝑅 (1

𝑛12 −

1𝑛2

2) 𝑎𝑥2 + 𝑏𝑥 + 𝑐 = 0

𝑡1 2⁄ =1

𝑘[𝐴]0 𝑘 = 𝐴𝑒(−𝐸𝑎 𝑅𝑇⁄ ) 𝑥 =

−𝑏 ± √𝑏2 − 4𝑎𝑐2𝑎

𝐸° =0.0592

𝑛𝑒log 𝐾 Δ𝐸 = −𝑅𝐻 (

𝑍2

𝑛𝑓2 −

𝑍2

𝑛𝑖2)

ln (𝑘2

𝑘1) =

𝐸𝑎

𝑅(

1𝑇1

−1𝑇2

) ln (𝐾2

𝐾1) =

∆𝐻𝑅

(1𝑇1

−1𝑇2

) 𝑝𝐻 = 𝑝𝐾𝑎 + log ([𝑐𝑜𝑛𝑗.𝑏𝑎𝑠𝑒][𝑐𝑜𝑛𝑗.𝑎𝑐𝑖𝑑]) 𝑛𝐹𝐸° = 𝑅𝑇 ln 𝐾