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University of Saskatchewan Department of Chemistry CHEMISTRY 112.3 Final Examination (Dec. 15th, 2012, 9:00 am – noon) Family Name (please print carefully!)____________________________________________ Given Name (please print carefully!)_____________________________________________ Student Number

Signature___________________________________

Please indicate your section with an “X” in the list column: Section 01 MWF 8:30 am Section 03 MWF 9:30 am Section 05 TTh 10:00 am Section 97 Muenster Section C11 Melfort Section C15 Prince Albert

Dr. K. Brown Dr. S. Urquhart Dr. R. Scott Dr. A. Szmigielski Dr. A. Szmigielski Dr. R. Catton

INSTRUCTIONS - PLEASE READ THIS FIRST! a. This is a closed-book examination. A data-sheet with a Periodic Table accompanies this examination paper; no other paper (or device) containing information relevant to this exam is permitted. b. Simple scientific calculators (maximum two-line display) are permitted; graphing calculators, PDA's, electronic dictionaries, etc., are not. c. This examination paper has 14 pages; ensure that your copy is complete. d. Answer multiple choice questions in Section A by circling a response on this paper AND by filling in the corresponding response on the blue opscan sheet USING ONLY A SOFT-LEAD PENCIL. No deductions will be made for incorrect answer. Multiple answers will be treated as NO answer; if you change your mind, erase carefully. In the event of a discrepancy between an answer on the examination paper and on the computer sheet, the response on the opscan sheet will count. e. Answer the questions in Section B on this examination paper. Show all work; this will be graded. f. If you have not already done so, please fill out the top of this paper now, and write your name (legibly!) and code your student number on the computer blue sheet in soft pencil. g. You can use the backsides of the pages as scratch paper (more paper will be available on request). Questions

Maximum Marks

Section A (Q1 – Q42)

Marks Earned

63

(1.5 marks each) Section B

Total

B1

8

B2

9

B3

10

B4

10 100 1

PART A 1) The number of neutrons, protons, and electrons in 31P3- are: A) B) C) D) E)

15 neutrons, 31 protons, 15 electrons 16 neutrons, 15 protons, 18 electrons 31 neutrons, 15 protons, 18 electrons 15 neutrons, 16 protons, 12 electrons 16 neutrons, 16 protons, 18 electrons

2) What is the atomic mass of 12C? A) 6 amu B) 12 amu C) 12.011 amu D) Cannot be known without weighing out 1.00 moles of 12C E) Cannot be known without knowing the mass of individual protons and neutrons 3) What is the atomic mass of an element if 4.00 grams of it contains 2.98 x 1022 atoms? A) B) C) D) E)

20.2 amu 80.8 amu 19.7 amu 8.08 amu 2.02 amu

4) Maprotiline has the following mass composition: C 86.59%, H 8.35%, N 5.05%. The empirical formula of maprotiline is: A) C7H8N3 B) C20H23N C) C87H8N5 D) C3H3N E) C14H14N

5) Choose the incorrect name formula combination: A) Fe2O3 iron (III) oxide B) H2SO3 sulfurous acid C) NH4ClO3 ammonium chlorate D) CaH2 calcium hydride E) SiO2 silicon oxide

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6) Given the following reactions: Fe (s) + Br2 (g) Æ FeBr2 (s) 3 FeBr2 (s) + Br2 (g) Æ Fe3Br8 (s) If each reaction gives an 82% yield, what mass of Fe3Br8 is produced from 1.00g Fe, assuming Br2 is in excess? A) 4.81 g B) 3.94 g C) 2.65 g D) 3.23 g E) 2.57 g 7) Determine the mass percent of H in NH4Cl. A) 19% B) 7.5% C) 14% D) 3.7% E) 1.9 % 8) Which statement below is true? A) Metals gain electrons to have a positive charge B) Metals gain electrons to have a negative charge C) Metals lose electrons to have a positive charge D) Nonmetals always lose electrons to have a positive charge. E) Transition metals can gain 2 or more electrons to become metal ions. 9) How much Cl2(g), in grams, is required to produce 12.0 g CCl4 according to the following reaction, assuming that methane gas (CH4) is in excess: CH4 (g) + 4 Cl2 (g) Æ CCl4 (g) + 4 HCl (g) A) 12.0 g B) 5.53 g C) 22.1 g D) 1.38 g E) 11.0 g

10) What is the answer with the correct number of significant figures of the following calculation: 75.032 + 2.3 +0.0046 10.2 A) 7.6 B) 7.57 C) 7.58 D) 7.578 E) 7.52 3

11) Titanium(IV) oxide (TiO2) is produced by the action of sulphuric acid on FeTiO3. FeTiO3 (s) + H2SO4 (aq) Æ TiO2 (s) + FeSO4 (s) + H2O (l) In a reaction, 8.00x103 kg of FeTiO3 yielded 3.67x103 kg of TiO2. What is the percent yield of the reaction? A) 1.15% B) 115% C) 45.9% D) 87.1% E) 8.45% 12) To determine molarity of an HCl solution, a 0.2400 g sample of Na2CO3 is titrated with 23.04 mL of HCl solution. What is the molarity of the HCl solution? Na2CO3(s) + HCl(aq) → NaCl(aq) + H2O(l) + CO2(g)

(unbalanced reaction)

A) 0.0393 M B) 0.0983 M C) 0.1310 M D) 0.1966 M E) 0.3931 M 13) In which compound the oxidation state of carbon is +4? A) CO2 B) CaCO3 C) CCl4 D) H2CO3 E) All of the above 14) Krypton gas in an 18.5-L cylinder exerts a pressure of 11.2 atm at 28.2 0C. How many grams of krypton are present? A) 8.38 g B) 502 g C) 702 g D) 755 g E) 777 g 15) Which gas occupies the largest volume at STP? A) 2.5 g H2 B) 2.5 g Cl2 C) 2.5 g He D) 2.5 g CO2 E) All have the same volume

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16) What is the total pressure if 1.0 g of H2 and 5.0 g of He are mixed in a 5.0 L flask at 20oC? Assume both species are ideal gases. A) 3.6 atm B) 2.4 atm C) 6 atm D) 8.4 atm E) No way of knowing with information given 17) A 1.00 L flask is filled with 0.160 g of unknown gas at 743 mmHg and 25 0C. Calculate the molar mass and identify the gas. The unknown gas is: A) CO2 B) O2 C) Ne D) He E) can be any of the above 18) Oxygen gas, generated by the reaction 2 KClO 3 (s) → 2 KCl (s) + 3 O2 (g) is collected at 27.0 0C and fills a 2.00 L vessel at a pressure of 750 Torr. What is the amount (in mol) of KClO3 consumed in this reaction? A) 0.0790 mol B) 0.119 mol C) 0.0534 mol D) 0.0813 mol E) 2.00 mol 19) How much heat is required to warm 1.50 kg of sand from 25 0C to 100 0C? Given: specific heat capacity of sand, Cs = 0.84 J/g 0C A) 6.33 x 104 J B) 7.85 x 104 J C) 8.30 x 104 J D) 9.45 x 104 J E) 10.8 x 104 J 20) How much heat is released by combustion of 177 mL of acetone (C3H6O)? Given: the density of acetone is 0.788 g/mL and ΔHrxn = -1790 kJ/mol. C3H6O(l) + 4 O2(g) → 3 CO2(l) + 3 H2O(g) A) –4.30 x 103 kJ B) –5.50 x 103 kJ C) –6.61 x 103 kJ D) –7.00 x 103 kJ E) –7.89 x 103 kJ 5

21) Calculate ΔHrxn for the reaction: Fe2O3(s) + 3 CO(g) → 2 Fe(s) + 3 CO2(g) Using the following reactions and ΔH’s. 2 Fe(s) + 3/2 O2(g) → Fe2O3(s) CO(g) + 1/2 O2(g) → CO2(g)

ΔH = − 824.2 kJ ΔH = − 282.7 kJ

A) –51.1 kJ B) +16.3 kJ C) –16.3 kJ D) –23.9 kJ E) +23.9 kJ 22) A 31.1-g block of pure gold (Cs of gold = 0.128 J/g 0C) initially at 69.3 0C is submerged into 64.2 g of water (Cs of water = 4.18 J/g 0C) at 27.8 0C. What is the final temperature of both substances at thermal equilibrium? A) 28.0 0C B) 28.4 0C C) 28.8 0C D) 32.2 0C E) 33.5 0C 23) Arrange the following elements in order of decreasing first ionization energy (from highest to lowest): Fluorine, Potassium, Magnesium, Phosphorus, Sulfur. A) F > S > P > Mg > K B) F > S > P > K > Mg C) F > P > S > Mg > K D) P > S > F > K > Mg E) S > F > P > Mg > K 24) According to Hund's rule, which element is expected to contain unpaired electrons? A) Sr B) Zn C) Ge D) All of A, B, and C E) None of A, B, or C 25) Which of the following atoms or ions is paramagnetic: Be, Na, Ne, S2-, B, Fe3+ ? A) Be, S2-, Ne B) Na, S2-, Fe3+ C) Fe3+, Na, Be D) Na, B, Fe3+ E) B, Fe3+, S2-

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26) Which of the following statements is correct with respect to the as-yet unknown element with the atomic number 119? (Note: g orbitals wouldn’t be used until hypothetical element #121) A) It will be a member of the alkali metal group (1A) B) It will have a filled 7d subshell C) It will likely have a first ionization energy greater than that of radon (Z=86) D) It will be a noble gas E) None of the above 27) A possible set of quantum numbers for the last electron added to complete the electron configuration of an atom of selenium in its ground state is: A) B) C) D) E)

n= 4; n= 3; n= 4; n= 3; n= 4;

l=0; l=0; l=1; l=1; l=2;

ml=0; ml=+1; ml=-1; ml=+1; ml=+2;

ms=+1/2 ms=-1/2 ms=+1/2 ms=-1/2 ms=-1/2

28) Which element has the following electron configuration? [Kr]5s24d105p4 A) Sn B) Sb C) Pb D) Ge E) Te 29) Which of the following orbitals cannot/does not exist? A) 6s B) 3p C) 2d D) 5g E) 7f 30) Which of the following statements for a group 7A element, X, is true? A) Reaction with a group 1A alkali metal (M) yields a compound with the formula MX2 B) Reaction with a group 2A alkaline earth metal (E) yields a compound with the formula E2X C) Ion of element X has a -1 charge D) Ion of element X has a -2 charge E) Element X is relatively inert and does not react with other elements

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31) What is the wavelength of an electron that is moving at a velocity of 680 m/s? A) 5.8 x 10-1 m B) 7.4 x 10-2 m C) 7.4 x 10-4 m D) 1.1 x 10-6 m E) none of the above 32) Arrange the following isoelectronic ions in order increasing radius: Ca2+, S2-, Cl-. (Smallest to largest) A) Ca2+< Cl- < S2B) Cl- < Ca2+< S2C) Ca2+< S2-< ClD) S2-< Cl- < Ca2+ E) Cl- < S2- < Ca2+ 33) For the anion Te2-, which of the following statements is correct? A) It is isoelectronic with Kr B) It will combine with Al3+ to form the compound Al2Te3 C) It has 52 electrons D) All of A, B and C are correct E) None of A, B and C is correct 34) Which of the following descriptions is correct? Given electronegativity values: Cs: 0.8 H: 2.1

Br: 2.8

N: 3.0

Cl: 3.0

O: 3.5

F: 4.0

A) CsF – polar covalent B) Cl2 – ionic C) NO – non-polar D) HCl – polar covalent E) BrCl – polar covalent 35) What is the formal charge on P in PCl5? A) 5 B) 2 C) 1 D) 0 E) -1 36) Given the bond enthalpies below, compute the enthalpy change for the following chemical reaction: NH3 (g) + Cl2 (g) Æ NH2Cl (g) + HCl (g) Bond energies N-H (389 kJ/mol); Cl-Cl (243 kJ/mol); N-Cl (201 kJ/mol); and H-Cl (431 kJ/mol) A) -393 kJ/mol B) -1100 kJ/mol C) +71 kJ/mol D) +393 kJ/mol E) 0 kJ/mol 8

37) A molecule has the formula ML2. Atom M is the central atom and the L-M-L bond angle is 117o. What are the most likely electron groups? A) Two bonds and no non-bonding pairs B) Two bonds and one non-bonding pair C) Two bonds and two non-bonding pairs D) Two bonds and three non-bonding pairs E) Three bonds an no non-bonding pairs 38) How many equivalent resonance structures does the ion NO3- have? A) 1 B) 2 C) 3 D) 5 E) 8 39) Which of the following molecules has a net dipole moment? A) BF3 B) BeCl2 C) CO2 D) CH4 E) NH3 40) What intermolecular force is the most important between CH3Cl molecules in a pure sample of the compound in the liquid phase? A) Ion – ion B) Ion – dipole C) Dipole – dipole D) Dispersion E) Covalent bonding 41) Which of the following compounds has the highest boiling point? A) CH4 B) H2O C) LiF D) CH3Cl E) N2 42) Ethanol (C2H5OH) has a heat of fusion of 5.01 kJ/mol. How much heat is required to melt 137 g of ethanol. A) 1.70 x 103 kJ B) 129 kJ C) 686 kJ D) 5.01 kJ E) 14.9 kJ

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PART B Use the available space to answer the following questions. B1. (8 marks) Mg (s) will react with aqueous HCl to generate H2 gas and magnesium chloride. (a) Write the balanced equation for this reaction (2 marks).

(b) If one started with 10.0 g of Mg and 25.0 mL of a 1.00 M solution of HCl, how many moles of H2 gas would be evolved? (4 marks)

(c) Assuming STP conditions, what would the volume of this much H2 gas be? Assume H2 gas behaves as an ideal gas. (2 marks)

10

B2. (9 marks) One of the main emission wavelengths of Helium-Neon lasers is an emission line at 633 x 10-9 m. (a) What is the frequency of light at this wavelength? (2 marks)

(b) What is the energy of a single photon at this wavelength? (3 marks)

(c) How many photons at this wavelength would be required to raise the temperature of 10.0 g of water at 25.0oC by 1.0oC? Assume all the light is absorbed by the water. Given: the specific heat capacity of water is 4.18 J/goC (4 marks)

11

B3. (10 marks) (a) Given the Pauling electronegativity values below indicate whether the following bonds are ionic, covalent polar or covalent non-polar: (3 marks) EN values: Ca: 0.8

H: 2.1

C: 2.5

Br: 2.8

Cl: 3.0

O: 3.5

F: 4.0

i) a Ca-F bond ii) a C-Br bond iii) a C-Cl bond

(b) Draw a Lewis dot structure for the following molecules and indicate whether they are polar or non-polar. (3 marks) The central atom has been underlined in each molecule. i) CF4

ii) CF3Cl

iii) CF 3(OH)

(c) Indicate the likely order of boiling points of the above three compounds (from lowest to highest), taking into account intermolecular forces present in each liquid. (2 marks)

(d) Which of the above liquids would have the highest surface tension? (2 marks)

12

B4. (10 marks) Fill in the blanks in this table. The central atom for each species has been underlined. If there are resonance structures, just show one of them. 1 mark for each blank. Species

Best Lewis Dot Structure

Resonance structures possible? (Y/N)

Formal Charge of Central Atom

No

0

Electron Group Geometry

Molecular Group Geometry (Shape)*

BrF5

XeF2 0

No

HCN

No

0 linear

PO3Trigonal planar

Trigonal planar

0

* What is the shape of the molecule? Either use the correct terminology for the geometry or provide a drawing. In the case of a drawing, it must be unambiguous, with important bond angles indicated. THE END.

13

1 1A 1 1.00794

2 2A

3

4

H

18 8A

Periodic Table of the Elements 13 14 15 3A 4A 5A 5

6

7

16 17 2 He 6A 7A 4.00260 8

9

10

B

C

N

O

F

Ne

6.941

9.01218

10.811

12.011

14.0067

15.9994

18.9984

20.1797

11

12

13

14

15

16

17

18

Li Be Na Mg

4

5

6

7

8

9

10

11

12

Si

P

S

24.3050

3

Al

22.9898

26.9815

28.0855

30.9738

32.066

35.4527

39.948

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

K

Ca Sc Ti

V

Cl Ar

Cr Mn Fe Co

Ni

Se

Br Kr

39.0983

40.078

44.9559

47.88

50.9415

51.9961

54.9381

55.847

58.9332

58.693

63.546

65.39

69.723

72.61

74.9216

78.96

79.904

83.80

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

Cu Zn Ga Ge As

Te

I

Xe

85.4678

87.62

88.9059

91.224

92.9064

95.94

(98)

101.07

102.906

106.42

107.868

112.411

114.818

118.710

121.757

127.60

129.904

131.29

55

56

57

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

Rb Sr

Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb

Cs Ba La Hf Ta

W

Re Os

Ir

Pt

Au Hg Tl Pb Bi

178.49

180.948

183.84

186.207

190.23

192.22

195.08

196.967

200.59

104

105

106

107

108

109

110

111

112

132.905

137.327

138.906

87

88

89

Fr Ra Ac Rf Db Sg (223)

226.025

227.028

(261)

207.2

208.980

(209)

(210)

(222)

66

67

68

69

70

71

Bh Hs Mt

(262)

(263)

(262)

(265)

(266)

(269)

(272)

(272)

58

59

60

61

62

63

64

65

Ce Pr

Po At Rn

204.383

Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

140.115

140.908

144.24

(145)

150.36

151.965

157.25

158.925

162.50

164.930

167.26

168.934

173.04

174.967

90

91

92

93

94

95

96

97

98

99

100

101

102

103

U

Th Pa 232.038

231.036

238.029

Physical Constants Constant Atomic mass unit Avogadro number Gas Constant

Np Pu Am Cm Bk Cf Es Fm Md No Lr 237.048

Symbol u NA R

Molar volume of an ideal gas at STP Planck constant

Vm h

Speed of light in a vacuum Rydberg Constant Electron mass Some SI Derived Units Physical Quantity Force Energy Pressure

c RH me Unit Newton Joule Pascal

(243)

(244)

(247)

(247)

(251)

(252)

(257)

(258)

(259)

(260)

Value –27 1.6605 × 10 kg 6.0221 × 1023 mol–1 0.082058 L atm mol– 1K–1 8.3145 J K–1 mol–1 62.364 L mmHg mol–1 K–1 22.414 L mol –1 6.6261 × 10 –34 J s 6.6261 × 10-34 m2kg/s –1 2.9979 × 108 m s –18 2.179 × 10 J 9.109 × 10 –31 kg

Symbol N J Pa

Definition kg m s– 2 kg m2 s –2 –2 –1 – 2 N m = kg m s

STP Conditions:

P = 1 atm = 760 torr = 760 mmHg = 101.325 kPa, Temperature = 0 ºC = 273.15 K h h , de Broglie's wavelength of particles: λ = He...