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Chem 17
7 Pra
ctice
Exa
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.
Chem 17
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Exa
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