chem lab section number: name (printed): signature: · this exam consists of 36 questions all of...

CHEM 200/202 Fall 2015 Exam 3-A November 14, 2015

CHEM _______ Lab Section Number: _____

Name (printed):_____________________________________________

Signature:______________________________________

This exam consists of 36 questions all of equal value for a total of 225 points. Make sure that your test has all of the pages. Please read each problem carefully. There are no intentionally misleading questions; each problem should be taken at its face value. Please mark your answers on the Scantron sheet provided to you and on the actual exam.

You will be given a periodic table and an exam information sheet to use during the exam. You may remove it from the exam make it more accessible. You may also use the designated Casio fx-300ms-plus calculator or equivalent non-programmable non-graphing scientific calculator during the exam. Use the back pages of the test as scratch paper. You are not allowed to use any devices capable of accessing the internet, textbooks, notes, or homemade reference sheets during the exam.

You may leave if you finish the exam early. Give the exam and the information sheet to your TA and leave quietly without disturbing other students. Before leaving, check that all your answers have been properly entered on the Scantron sheet and the exam and that your name is written on every page of the exam and on the Scantron sheet.

All cell phones and electronic devices must be turned off and put away. Please remove all hats and caps. Place your books and all papers out of sight under your seat. If the TA believes that you might be looking at your neighbor’s paper, you will be asked to move to a new location.

Exam scores will be posted on Blackboard as soon as the grading is complete. Your test will be returned to you in the first lab meeting of next week. If you have any questions regarding the grading of your exam, please notify your TA.

The time available for the exam is 120 minutes. Good luck!

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Name: ___________________________________________ Lab Section #: _______

Please mark your answers on the scantron sheet using a #2 pencil and also mark your answers on the exam itself.

1. Which one of the following properties is least characteristic of typical ionic compounds?

(a) high melting point(b) high boiling point(c) brittleness(d) poor electrical conductor when solid(e) poor electrical conductor when molten

2. In carbon disulfide, how many lone pairs of electrons are on each sulfur atom?

(a) 0(b) 1(c) 2(d) 3(e) 4

3. Which of the following molecules does not have a bent shape?

(a) H2O(b) I3−(c) SO2(d) O3(e) SCl2

4. In the molecule to the right, how many of the atoms have sp3 hybridization?

(a) 1(b) 2(c) 3(d) 4(e) 5

5. What is the shape of a molecule of PF5?

(a) Trigonal pyramidal(b) Square pyramidal(c) Trigonal bipyramidal(d) Octahedral(e) See-saw

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6. What is the actual bond angle between oxygen-sulfur bonds on molecule of SO3?

(a) 109.5°(b) < 109.5°(c) > 109.5°(d) 120°(e) <120°

7. In the following Lewis structure for ClO3F, chlorine has a formal charge of ____ and an oxidation number of ____.

(a) 7, 7(b) 7, -1(c) 1, 1(d) 1, -1(e) 1, 7

8. Which of the following elements is the least electronegative?

(a) Si(b) Se(c) S(d) Sc(e) Sr

9. In which of these substances are the atoms held together by polar covalent bonding?

(a) SrCl2(b) CsCl(c) BCl3(d) TiF2(e) S8

10. Select the compound with the lowest (i.e., least negative) lattice energy.

(a) CsBr(s)(b) NaCl(s)(c) SrO(s)(d) CaO(s)(e) KBr(s)

11. Which molecular formula is incorrectly matched with the molecular shape?

(a) SF4 - Square planar(b) CHCl3 - Tetrahedral(c) BrF3 - T-shaped(d) IOF5 - Octahedral(e) ClO3− - Trigonal pyramidal

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12. Phosphoryl iodide is used in the preparation of organophosphorus derivatives and phosphate esters. Select the best Lewis structure for POI3.

13. Of the molecules drawn below, which is non-polar? If they are all polar, select answer E.

14. In molecules of carbon dioxide both the carbon and oxygen atoms are hybridized. What are their respective hybridizations?

(a) C: sp O: sp2(b) C: sp2 O: sp3(c) C: sp3 O: sp(d) C: sp O: sp(e) C: sp2 O: sp2

15. Arrange aluminum, indium, nitrogen, oxygen, and phosphorus in order of increasing electronegativity.

(a) Al < In < N < P < O(b) Al < In < P < O < N(c) In < Al < P < N < O(d) In < O < P < Al < N(e) None of these choices is correct.

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16. Select the strongest bond in the following group.

(a) C−S(b) C−O(c) C=C(d) C=O(e) C−F

17. The lattice energy for ionic crystals decreases as the charge on the ions _____________

and the size of the ions __________________.

(a) increases, increases(b) increases, decreases(c) decreases, increases(d) decreases, decreases(e) None of these choices is generally correct.

18. Select the element whose Lewis symbol is correct.

19. In which of the Lewis structures below doe the nitrogen atom have a formal charge of −2?

20. Which of the following is a molecule that is both polar and has a linear shape?

(a) CO2(b) H2S(c) O2(d) HCN(e) XeF2

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To answer the next three questions use the molecular orbital diagram below.

21. How many electrons are present in antibonding molecular orbitals?

(a) 2(b) 4(c) 6(d) 8(e) 10

22. What is the bond order for the molecule?

(a) 3(b) 2.5(c) 2(d) 1.5(e) 1

23. What is the most likely formula for the molecule represented in the molecular orbital diagram?

(a) O22−

(b) ONe(c) ONe+

(d) OF(e) OF+

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24. Which of the following compounds displays the greatest ionic character in its bonds?

(a) NO2(b) CO2(c) H2O(d) H2S(e) NH3

25. How many electrons are found within a pi (π) bond?

(a) 1(b) 2(c) 3(d) 3.14(e) 4

26. Which is not a possible shape for molecules with trigonal bypiramidal electron group arrangements?

(a) Trigonal planar(b) Linear(c) See-saw(d) T-shaped(e) All the above shapes are possible.

27. Which one of the following Lewis structures is definitely incorrect?

H C N S O

Pauling Electronegativity 2.1 2.5 3.1 2.5 3.5

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28. Hydrogenation of double and triple bonds is an important industrial process. Calculate (in kJ) the standard enthalpy change ∆H° for the hydrogenation of ethyne (acetylene) to ethane, depicted in the unbalanced reaction below.

C2H2(g) + H2(g) → C2H6(g)

(a) −296 kJ(b) −51 kJ(c) −533 kJ(d) −1122 kJ(e) −728 kJ

29. The lattice energy of BaCl2 is the energy change for which one, of the following processes?

(a) Ba2+(s) + 2Cl−(g) → BaCl2(g)(b) BaCl2(g) → BaCl2(s)(c) Ba(g) + 2Cl(g) → BaCl2(s)(d) BaCl2(aq) → BaCl2(s)(e) BaCl2(s) → Ba2+(g) + 2Cl−(g)

30. The molecules below are described as either polar or non-polar. Which one is incorrectly described?

(a) OCN− - Polar(b) CH2Cl2 - Non-polar(c) CO2 - Non-polar(d) NH3 - Polar(e) SO2 - Polar

31. How many faces and how many vertexes (corners), respectively, are there in a trigonal bipyramid?

(a) 4 and 4(b) 5 and 5(c) 5 and 6(d) 6 and 5(e) 6 and 8

C≣C C=C C−C C−H H−H

Bond energy (kJ/mol) 839 602 347 413 432

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32. Considering the angle between bonds to hydrogen atoms, which of the molecules listed below will have an actual bond angle that is that is exactly 120°?

(a) BeH2(b) AlH3(c) H2S(d) AsH3(e) SiH4

33. Which statement best explains why the sigma (σ) bond is stronger than the pi (π) bond?

(a) Sigma bonds involve more electrons than pi bonds.(b) Sigma bonds are shorter than pi bonds.(c) There is greater overlap of orbitals in the end-to-end form of sigma bonds.(d) Single bonds are always stronger than double of triple bonds.(e) The question is incorrect, sigma bonds are weaker than pi bonds.

34. In which one of the following molecules is the best Lewis structure a resonance structure?

(a) CO2 (C = central atom)(b) ClO3− (Cl = central atom)(c) COCl2 (C = central atom)(d) NO2+ (N = central atom)(e) HCN (C = central atom)

35. Which of the following molecules has a central atom that has sp3d hybridization?

(a) SO42−

(b) CH4(c) SF6(d) PCl5(e) H2O

36. How many sigma (σ) and pi (π) bonds are there in a molecule of sulfuric acid (H2SO4)?

(a) σ = 4 π = 2(b) σ = 7 π = 1(c) σ = 2 π = 5(d) σ = 3 π = 3(e) σ = 6 π = 2

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©

2008 San D

iego State U

niversity, Departm

ent of Chem

istry

Periodic Table of the Elements

1

18

1 1

H

1.008

2

13 14

15 16

17 2

He

4.003

2 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

3 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

4 19

K

39.10

20

Ca

40.08

21

Sc 44.96

22

Ti 47.87

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 65.39

31

Ga

69.72

32

Ge

72.64

33

As

74.92

34

Se 78.96

35

Br

79.90

36

Kr

83.80

5 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

48

In 114.8

50

Sn 118.7

51

Sb 121.8

52

Te 127.6

53

I 126.9

54

Xe 131.3

6 55

Cs

132.9

56

Ba

137.3

57-70

* 71

Lu 175.0

72

Hf

178.5

73

Ta 180.9

74

W

183.8

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

[220]

7 87

Fr [223]

88

Ra

[226]

89-102

** 103

Lr [262]

104

Rf

[261]

105

Db

[262]

106

Sg [266]

107

Bh

[264]

108

Hs

[277]

109

Mt

[268]

Metals

Non

Metals

*

Lanthanoids 57

La 138.9

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

**

Actinoids

89

Ac

[227]

90

Th 232.0

91

Pa 231.0

92

U

238.0

93

Np

[237]

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]

13

San Diego State University |

CHEM 200 Exam/Quiz Information Sheet – Fall 2013

Physical Quantitiesatomic mass unit (amu) = 1.66056 x 10-27 kg

Avogadro’s number = 6.022 x 1023

universal gas constant (R) = 8.314 J/Kumol = 0.08206 Luatm/Kumol

absolute zero = -273.15 ˚C = 0 K

specific heat capacity of water (cH2O) = 4.184 J/guK

speed of light (c) = 3.000 x 108 m/s

Planck’s constant (h) = 6.626 x 10-34 Jus

Conversion Factors1 angstrom (Å) = 10-10 m

1 atm = 1.01325 x 105 Pa = 1.01325 bar = 760 Torr

1 calorie = 4.184 J

1 joule = 1 kgum2/s2

Equations

PV = nRT

PA = XA u Ptotal

d = (molar mass) = PRT

urms = molar mass

3RT

6E = q + w

6Hrxn = Y6H°f(products) - Y6H°f(reactants)

heat capacity = q/6T

specific heat capacity (c) = q/(mass = 6T)

speed of light (c) = i x h

Ephoton = hi = hch

Eelectron = -2.18 x 10-18 J (Z2

n2)h = h

mu1h

= 1.096776 x 107 m-1 ( 1n1

21n2

2– ), where n2 > n1

chem lab section number: name (printed): signature: · this exam consists of 36 questions all of...

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