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mProf. Thomas Greenbowe Prof. Gordon Miller Dr. Cristina Bonaccorsi This exam consists of 2 parts on 8 pages

CHEM 177 Hour Exam III

October 22, 2012

Name______________________ Recitation TA_______________ Recitation Section____________

Grading

Parts

Part I

Page 3

Page 4

Page 5

Part II Page 5

Page 6

Page 7

SUBTOTAL

Grand Total

Points

18 pts

18 pts

9 pts

20 pts

16 pts

20 pts

56 pts

101 pts

Score

on scantron sheet

________

________

________

________

________

________

TA Name Sections Time Berry 14, 38 10, 2 Bobbitt 36, 48 2, 3 Boschen 3, 9 8, 9 Burgin 53, 58 4, 5 Carraher 6, 12 9, 10 Castle 40, 46 2, 3 Chaudhary 47 3 Cole 19 11 De Silva 21, 31 11, 1 Flood 54 5 Friedrichsen 7, 30 9, 1 Ganesh 5, 11 8, 9 Geraskin 20, 26 11, 12 Geraskina 17, 23 10, 11 Hochstein 35, 42 1, 2 Joshi 16, 29 10, 12 Keller 1 8 Khan 22, 49 11, 4 Kumar 28, 34 12, 1 Kwolek 4, 10 8, 9 Lei 44, 52 3, 4 Lesoine 15, 57 10, 5 Nelson 33, 41 1, 2 Nguyen 24 12 Peeraphatdit 32, 39, 45 1, 2, 3 Thooft 43, 51 3, 4 Vangaveti 18, 27 11, 12 Wang 50, 55 4, 5 Wanninayake 2, 8 8, 9 Weerasekara 13, 25 10, 12 Xu 37, 56 2, 5

NOTE: To receive full credit on problems in pages 5-7: #16-21, you must clearly show all work and your method of determining the answer must be clear. The final answer must be reported to the correct number of significant figures and have the correct units. Questions are written on both sides of each page. The last page contains useful information and a periodic table; the last page may be removed and used for scratch paper and as a reference. Do not put answers or work on the tear away page. At the time of the printing of this exam, the day and time for the Final Exam for Chem 177 has not yet been announced by the Registrar’s Office.

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mPlease read the following instructions carefully before proceeding! Part I of your exam will be computer graded. In order for the computer to identify who you are, it is important that you complete the information section properly. Failure to correctly bubble in your name, ID number, and section will result in a 10 point deduction from your exam score.

You must use a #2 pencil and completely fill in the appropriate circles on the BLUE computer scan sheet. 1. 2.

3.

To help you code the correct circles, first write your last name, first name, and middle initial in the boxes (skip a space between each). Then darken the circles that match the letters in the box above it. See the sample to the right. Write the middle nine digits of your ISU identification number in the boxes A-I. Do not skip any spaces. Below each number, darken the circle that matches this number. For example, 123456789. See the sample at bottom right.

If you do not know your ISU identification number at the time you take the exam, you must report to Hach Hall Room 1227 by 9:30 P.M. of the night of the exam and show your ID to one of the professors of this course. Write your recitation section number in the special code area, boxes K-L, as two digits. Do not skip any spaces. For example, if you are in section 8, write 08. Again, darken the circle that matches the number above it. See the sample at bottom far right.

In Part I, select the one best answer for each question. Place your answer on the computer answer sheet by darkening the proper circle for that question. Your computer scan sheet will be your official answer sheet for Part I. All material (exam, answer sheet, scratch paper) must be returned to your TA in order for us to grade your exam.

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Part I: Multiple Choice (15 questions at 3 pts each = 45 points). The answer you fill in on your bubble sheet is the one that will count. You should circle the answer on this sheet for your own reference. There is only one best answer for each question. 1. Which of the following reactions has its enthalpy change equal to ΔH°f (CaCO3)?

a) CaO(s) + CO2(g) → CaCO3(s)

b) CaO(s) + C(s, graphite) + O2(g) → CaCO3(s)

c) Ca(s) + C(s, graphite) + O2(g) → CaCO3(s)

d) Ca2+(aq) + CO32–(aq) → CaCO3(s)

2. Given the following reactions, 2S (s) + 3O2 (g) → 2SO3 (g) ΔH = –790 kJ S (s) + O2 (g) → SO2 (g) ΔH = –297 kJ

What is ΔH° for the reaction 2SO2 (g) + O2 (g) → 2SO3 (g)? a) 196 kJ b) –196 kJ c) 1087 kJ d) –1384 kJ

3. A 25.5-g piece of cheddar cheese contains 28.0% protein, 37.0% fat, and 4.0% carbohydrate. The

respective fuel values for protein, fat, and carbohydrate are 17, 38, and 17 kJ/g, respectively. What is the fuel value for this piece of cheese?

a) 99 kJ b) 330 kJ c) 5.0 102 kJ d) 790 kJ

4. Molecular vibrational energy transitions are observed in the infrared, molecular rotational transitions in the microwave, and electronic transitions in the ultraviolet-visible range of the EM spectrum. Which transitions occur with the lowest wavelengths of light?

a) Electronic transitions b) Vibrational transitions c) Rotational transitions d) Electronic and rotational transitions

5. The wavelength of a photon that has an energy of 6.33 × 10–18

J is __________ m.

a) 3.79 × 10–7

b) 3.10 × 10–8

c) 2.38 × 1023

d) 4.21 × 10–24

e) 9.55 × 1015

6. Which atomic orbitals have two nodal surfaces?

a) 2s and 2p b) 2p and 3p c) 3s and 3p d) all p atomic orbitals

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7. A neutral bromine atom has how many valence electrons?

a) 1 b) 5 c) 7 d) 17 8. Which one of the following represents an acceptable possible set of quantum numbers

(in the order n, l, ml, ms) for an electron in an atom?

a) 2, 1, –1, +½ b) 2, 1, 0, 0 c) 2, 2, 0, +½ d) 2, 0, 1, –½ e) 2, 0, 2, +½

9. [Ar]4s23d104p3 is the electron configuration of a(n) __________ atom.

a) As b) V c) P d) Sb e) Sn 10. The electron configuration of a ground-state Pd2+ cation is __________.

a) [Ar]4s23d104p65s24d6 b) [Kr]4d

8 c) [Kr]5s

24d

6 d) [Kr] 5s

13d

7 e) [Kr]5s

24d

8

11. Which electron configuration represents a violation of Hund's rule for an atom in its ground state?

a) b) c) d) e)

12. Which has the highest Zeff for its valence electrons?

a) Na b) K c) Si d) Cl

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13. Of the following, which gives the correct order for atomic radius for Mg, Na, P, Si and Ar?

a) Mg > Na > P > Si > Ar b) Ar > Si > P > Na > Mg c) Si > P > Ar > Na > Mg d) Na > Mg > Si > P > Ar e) Ar > P > Si > Mg > Na

14. Which of the following is an isoelectronic series?

a) B5–, Si4–, As3–, Te2– b) F–, Cl–, Br–, I– c) S, Cl, Ar, K d) Si2–, P2–, S2–, Cl2– e) O2–, F–, Ne, Na+

15. Which of the following species has the largest radius? a) Rb+ b) Sr2+ c) Br– d) Kr e) Ar Part II: Problems (4 questions = 56 points). Show all work to receive credit. Place your answers in the answer spaces. 16. (16 pts) Fill in all blank boxes in the following table. You may use appropriate short-hand notation for

the electronic configurations.

Element Atomic Number

Ground State Electronic Configuration

(2 pts) # Core

Electrons # Valence Electrons

# Unpaired Electrons

Si 10

Cu

Se2–

44 1s22s22p63s23p63d104s24p64d4 40 4

17. (4 pts) Complete the Energy Level Diagram by drawing in the electrons in a ground state Cu atom. Use the half arrow notation for electrons: , and identify the name of subshells (ns, np, nd).

and

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Total Pts ________

18. (16 pts, in four parts on this page) Acetylene gas (C2H2) can be made by combining calcium carbide (CaC2, a solid) with liquid water. (a) (2 pts) Write the balanced chemical equation (including phases) for this reaction involving 1 mole

of CaC2. One of the products is CaO(s).

(b) (2 pts) The name of CaO is ___________________________________.

(c) (6 pts) Use the data in the table below to calculate the ΔH° for the reaction in (a).

Ans. _____________

(d) The reaction in (a) was conducted in a constant pressure calorimeter by adding 64.1 g of CaC2(s) to water. Both reactants were initially at 25.0 °C. The final temperature of water was 66.7 °C.

i. (1 pt) What gains heat? Be specific to this problem ____________________________ ii. (1 pt) What loses heat? Be specific to this problem ____________________________

iii. (4 pts) Find the mass of water in the calorimeter. If you don't have an answer for part (b), use ΔH° = –55.0 kJ/mol. Assume that the specific heat of the solution is equal to that of water, 4.18 J/g °C.

Ans. _____________

Substance ΔH°f (kJ/mol)C2H2(g) +226.6 H2O(l) –285.8 CaC2(s) –59.8 CaO(s) –635.6

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Total Pts ________

19. (6 pts) Electromagnetic radiation with a wavelength of 531 nm appears as green light to the human eye. The energy of one photon of this light is 3.74 × 10–19 J. Thus, a laser that emits 1.3 × 10–2 J of energy in a pulse of light at this wavelength produces how many photons in each pulse?

20. (10 pts) Consider hydrogen atoms each undergoing the transition from n = 2 to n = 4.

a) (2 pt) This process is called absorption / emission. (circle one) b) (4 pts) Calculate the wavelength (nm) of light needed for this transition.

Ans. ________________ c) (4 pts) Calculate the energy (in kJ) needed for one mole of H atoms.

Ans. ________________

21. (4 pts) For each of the following atomic orbital drawings, (a) write the proper name (e.g., 3s, 2px,

etc.) and (b) identify the nodal surfaces by drawing dash lines on the diagrams below.

AO _________________ AO _________________

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INFORMATION

1 mole = 6.022 1023 molecules Esystem = Esurroundings

1 L = 1000 mL = 1000 cm3 E = q + w q = mCsT ΔH = qp

1 amu = 1 g/mol qreaction + qsolution = 0

1 cm = 10 mm 1 m = 109 nm

1 kJ = 1000 J h = 6.626 10–34 Joule-sec

c = 3.00 108 1 hertz = 1

E = –2.18 10–18 J

= c or f = c

1λ

R1n

1n

; R 1.097 10

m

E = h = or E = hf =

λ hmv

hp

Periodic Table of the Elements

103 Lr

(260)

102 No

(259)

101 Md

(258)

100 Fm

(257)

99 Es

(252)

98 Cf

(251)

97 Bk

(247)

96 Cm

(247)

95 Am

(243)

94 Pu

(244)

93 Np

(237)

92 U

238

91 Pa

231

90 Th 232

71 Lu 175

70 Yb

173

69 Tm 169

68 Er

167

67 Ho

165

66 Dy 162

65 Tb 159

64 Gd 157

63 Eu

152

62 Sm 150

61 Pm

(145)

60 Nd 144

59 Pr

141

58 Ce 140

8A 18

7A 17

6A 16

5A 15

4A 14

3A 13

Lanthanides

Actinides

109 Une

(266)

108 Uno

(265)

107 Uns

(262)

106 Unh

(263)

105 Ha

(262)

104 Rf

(261)

89 Ac

227

88 Ra

226

87 Fr

(223)

83 Bi

209

82 Pb

207

81 Tl

204

80 Hg 201

79 Au 197

78 Pt

195

77 Ir

192

76 Os

190

75 Re 186

74 W

184

73 Ta 181

72 Hf

178

57 La

139

56 Ba

137

55 Cs

133

51 Sb

122

50 Sn

119

49 In

115

48 Cd 112

47 Ag 108

46 Pd 106

45 Rh 103

44 Ru 101

43 Tc

(98)

42 Mo 95.9

41 Nb

92.9

40 Zr

91.2

39 Y

88.9

38 Sr

87.6

37 Rb

85.586 Rn

(222)

85 At

(210)

84 Po

(209)

52 Te 128

53 I

127

54 Xe

131

36 Kr

83.8

35 Br

79.9

34 Se

79.0

33 As

74.9

32 Ge

72.6

31 Ga

69.7

30 Zn

65.4

29 Cu

63.5

28 Ni

58.7

27 Co

58.9

26 Fe

55.8

25 Mn 54.9

24 Cr

52.0

23 V

50.9

22 Ti

47.9

21 Sc

45.0

20 Ca

40.1

19 K

39.1

18 Ar

39.9

17 Cl

35.4

16 S

32.1

15 P

31.0

14 Si

28.1

13 Al

27.0

2 He

4.00

10 Ne

20.2

9 F

19.0

8 O

16.0

7 N

14.0

6 C

12.0

5 B

10.88B

2B 12

1B 111098

7B 7

6B 6

5B 5

4B 4

3B 3

12 Mg

24.3

11 Na

23.0

4 Be

9.01

3 Li

6.94

2A 2

1A 1

1 H

1.01