CHEM 107 (Spring-2007)
Final Exam (104 pts)
Name: ------------------------------------------------------------------------, Clid # -----------------------------LAST NAME, First
(Circle the alphabet segment of your LAST NAME): A & B
C-G
H-L
M-P
R-Z
Please answer the following questions:
Part I: Multiple Choices (44 pts: 22 @ 2 pts each + 4 pts bonus). Circle the ONE best answer:
1. Which of the following species have square planar molecular shape?
I) SeF4
II) NH4+
III) XeF4
a) only III
b) only I
c) II and III
d) I, II and III
IV) SO32-
2. In the above question the hybridization of the central atom in each molecule or ion are as follows:
3.
a) sp3d, sp3, sp3d2 and sp3 respectively
b) sp3, sp3, sp3d2 and sp2 respectively
c) sp3d, sp3, sp3d2 and sp2 respectively
d) sp3d2, sp3, sp3 and sp2 respectively
A gold ring has a mass of 5.50 g, it absorbs 2.10 J when heated from 15.0 to 18.0 ºC, What is the
specific heat of the gold? (specific heat of gold is 0.129 J/g ºC)
a) 0.382 J/g ºC
b) -0.129 J/g ºC
c) 0.129 J/g ºC
d) 1.83 J/g ºC
4. Which of the following statements is false?
a) An electron transition from n = 4 to n = 2 emits energy.
b) Light emitted by an n = 5 to n = 2 transition will have a shorter wavelength than that from
n = 4 to n = 2 transition.
c) An atom of group 15 has three unpaired electrons.
d) None of the above.
5. Which of the following ions is expected to be paramagnetic that corresponds to the presence of
five unpaired electrons?
a) Cd2+
b) Co2+
c) Mn4+
d) Cr+
6. The ground state electron configuration of osmium, Os (Z = 76) is
a. [Xe] 4f146d6 6s2
b) [Xe] 4f14 5d6 6s2
c) [Xe] 4f14 6p6 6s2
d) [Xe] 4f14 5d6
7. The oxidation numbers of sulfur, S in H2S and S2O32- are:
a) 0 and +4, respectively
b) +2 and +4, respectively
c) -2 and +2, respectively
d) -2 and +4, respectively
1
8. Which of the following molecules is expected to be non-polar?
a) PCl3
b) SF2
c) BeF2
d) NF3
9. What is the final temperature (°C) is required for the pressure inside an automobile tire to increase
from 2.15 at 0 °C to 2.37 atm, assuming the volume remains constant?
a) 301
b) -25
c) 28
d) no answer was give
10. The concentration of cholesterol (C27H46O) in normal blood is approximately 0.005 M. How
many grams of cholesterol are in 750 mL of blood?
a) 3.75
b) 9.70 x 10-3
c) 1.93
d) 1.45
11. Calculate ∆H° for the following reaction using the given enthalpies of formation.
2 C2H2 (g) + 5 O2 (g)
∆Hf° (kJ/mol):
4 CO2 (g) + 2 H2O (g)
226.7
-393.5
b. +862 kJ
b) -862 kJ
c) +2511.0
d) -2511.0 kJ
-241.8
12. Which of the following has the smallest first ionization energy?
a) Br
b) Sn
c) Se
d) Cl
13. The greatest deviation from the Ideal Gas Law is expected at:
a) high T, high P
b) low T, high P
c) high T, low P
d) low T, low P
14. Which name is incorrect?
a) (NH4)2SO4: ammonium sulfate
b) SeO2: selenium sulfide
c) S2F2: disulfur difluoride
d) CuO: copper(II) oxide
15. The standard enthalpy change for the following reaction is +285.4 kJ.
3 O2 (g)
2 O3 (g)
What is the standard enthalpy of formation of O3 (g)?
a) +142.7 kJ
b) -142.7 kJ
c) +285.4 kJ
d) -285.4 kJ
16. Predict the product formed when calcium, Ca combines with arsenic, As?
a) Ca3As2
b) Ca2As3
c) CaAs
d) CaAs2
2
17. What volume, in mL of 0.750 M HCl would be required to neutralize 1.50 g sample of Ca(OH)2?
18.
a) 53.5
b) 26.7
c) 13.4
d) 35.0
Naturally occurring chlorine consists of two isotopes. The atomic mass of chlorine is
approximately 35.5. What are reasonable estimates of the relative percentages of 35Cl and 37Cl,
respectively?
a) 50, 50
b) 25, 75
c) 75, 25
d) 67, 33
19. An atom containing 34 protons and a mass number of 77, would be:
a) 77Se
b) 43Se
c) 77Tc
d) 43Tc
20. A solution of acetic acid, CH3COOH (60 g/mol), is 50.0% CH3COOH by mass and has a density
of 1.15 g/mL. calculate the molarity of the solution
a) 9.58
b) 0.958
c) 7.25
d) none of these
21. Which of the following ions has the smallest atomic radius?
a) Si
b) P
c) S
d) F
Questions 22-24: Consider the phase diagram of the
substance shown here.
22. Approximately what is the normal boiling point?
a) 170 ºC
b) 300 ºC
c) 460 ºC
23. What is the normal melting point of the substance?
a) 170 ºC
b) 180 ºC
c) 300ºC
24. What is the physical state of the substance of the substance under the conditions of T = 350 K,
P = 0.9 atm?
a) solid
b) liquid
c) gas
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Part II. Bonding and Chemical Equations (26 pts):
A) Bonding & molecular structure (12 pts):
1. Draw the Lewis structure for the SCN- ion, draw the resonance structures, if there is any then predict:
a) the molecular shape
b) hybridization of the central C atom
c) number σ and π bonds
d) bond angle
Lewis Structure & resonance structures (if any)
a) Molecular shape: -----------------------b) Hybridization of the central atom: ------c) # of σ bonds ------and # of π bonds -------d) Bond angle: -----------------
B) Chemical Equations (16 pts):
2. (8 pts) Balance the following redox equation in acidic solution:
MnO4- (aq) + Br- (s)
Mn2+ (aq) + Br2 (l),
Then identify the oxidizing agent and how many electron(s) are transferred per one mole of the
oxidizing agent.
Balanced equation:
Oxidizing agent: -------------Number of electrons/mole of oxidizing agent: --------
4
2. (6 pts) Write the balanced chemical equation and the net ionic equation for the reaction between
aqueous solutions of AgNO3 (aq) and CaBr2 (aq) and then identify the spectator ion(s)
Chemical equation:
Net ionic equation:
Spectator ion(s):
Part III. Calculations (30 pts: 5 @ 6 pts each) Show all work for full credit. Please express all
answers with the proper units and correct number of significant figures.
1. Given the following equations:
N2 (g) + 3 H2 (g)
∆Hrxn° = -92.2 kJ
2 NH3 (g)
2 H2 (g) + O2 (g)
2 H2O (l)
∆Hrxn° = -571.6 kJ
N2 (g) + O2 (g)
2 NO (g)
∆Hrxn° = +180.5 kJ
Determine the enthalpy change, ∆Hrxn° for the following reaction:
2 NO (g) + 2 O2 (g)
2 NH3 (g) + 2 H2O (l)
∆Hrxn° = ??
∆Hrxn° = -844.3 kJ
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2. Titanium(III) chloride, TiCl3 a substance used as a catalyst for preparing polyethylene, is made by
high-temperature reaction of TiCl4 vapor with H2 as follows:
2 TiCl4 (s) + H2 (g)
2 TiCl3 (s) + 2 HCl(g)
a) How many grams of TiCl4 are needed for complete reaction with 155 L of H2 at 435°C and
795 mmHg pressure?
b) How many liters of HCl gas at STP will result from the reaction described in part (a)?
a)
b)
3. Cisplatin, Pt(NH3)2Cl2 (300.1 g/mol) an anticancer agent used for the treatment of solid tumors, is
prepared by the reaction of ammonia with potassium tetrachloroplatinatate(II), K2PtCl4 (415.3 g/mol).
Assume that 10.0 g of K2PtCl4 and 10.0 g of NH3 are allowed to react
K2PtCl4 (aq) + 2 NH3 (g)
Pt(NH3)2Cl2 (s) + 2 KCl (s)
a) What is the limiting reactant?
b) How many grams of cisplatin are formed?
c) If 4.89 g of cisplatin, Pt(NH3)2Cl2 was produced. What is the %yield of the reaction?
a) Limiting reactant: K2PtCl4
b) 7.23 g
c) % yield = 67.6
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4. The reaction of a copper penny with nitric acid results in the formation of a red-brown gaseous
compound containing nitrogen and oxygen. A sample of the gas at a pressure of 727 mmHg and a
temperature of 18 ºC weighs 0.289 g in a flask with a volume of 157.0 mL. Calculate the molar mass
of the gas, and suggest a reasonable chemical formula for the compound (NO, NO2, N2O, N2O5,
N2O4).
M = 45.9 g/mol, NO2
5. Caproic acid, the substance responsible for the aroma of dirty gym socks and running shoes, contains
carbon, hydrogen and oxygen. On combustion analysis, a 0.450 g sample of carporic acid gives 0.418
g of H2O and 1.023 g of CO2. What is the simplest formula of caproic acid? If the molecular mass of
the compound is 116.2 g/mol, what is the molecular formula?
Simplest Formula
C3H6O
Molecular Formula
C6H12O2
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PREFERENCE SHEET FOR
CHEM 107
Final Exam – Spring 2007
You will have 140 minutes to complete this exam. The exam has 7 pages plus the Periodic Table and
Reference page.
When you are told to do so, tear off the Periodic Table cover sheet and use as required during the exam.
Equations and Constants:
q = m x c x ∆T
Density (d) = mass/volume
PV = nRT
K.E. = ½ mv2
Average speed of a gas, u = (3RT/M)1/2
(Rate of effusion of B/Rate of effusion of A) = (MA/MB)1/2 = tB/tA
ν = RH/h [1/(nlo)2 – 1/(nhi)2]
E=hν
E = - RH/n2
c=λν
RH = 2.180 x 10-18 J
h = 6.626 x 10-34 J.s
c = 3.00 x 108 m/s
Avogadro’s Number = 6.022 x 1023
R = 0.0821 L.atm/mol.K
1 atm = 760 torr = 760 mmHg
At STP 1 mol of a gas = 22.414 L
At STP: T = 273 K, P = 1 atm
General Solubility Guidelines
All nitrates are soluble.
All salts of sodium, potassium and ammonium are soluble.
All chlorides, bromides and iodides are soluble except Ag+, Hg22+, and Pb2+.
All sulfates are soluble except Ba2+, Sr2+, Pb2+ and Hg22+.
All acetates, chlorates and perchlorates are soluble.
Everything else (sulfides, carbonates, phosphates) will be considered insoluble.
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1
1
2
H
Periodic Table of the Elements
He
1.01
3
2
3
4
5
6
4.00
4
5
6
7
8
9
10
Li Be
B
C
N
O
F
Ne
6.94
9.01
10.81 12.01 14.01 16.00 19.00 20.18
11
12
13
14
15
16
17
Na Mg
Al Si
P
S
Cl Ar
22.99 24.30
26.98 28.08 30.97 32.06 35.45 39.95
21
19
20
K
Ca Sc Ti V
39.1
40.08 44.96 47.88 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.38 69.72 72.59 74.92 78.96 79.90 83.80
37
38
39
Rb Sr Y
22
40
23
41
24
25
26
27
28
29
30
31
32
33
34
35
18
36
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
42
43
44
45
46
47
48
49
50
51
52
53
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I
54
Xe
85.47 87.62 88.91 91.22 92.91 95.94 (98)
101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.1
55
76
56
57
72
73
74
75
77
Cs Ba La Hf Ta W Re Os Ir
78
79
80
81
82
83
84
85
86
Pt Au Hg Tl Pb Bi Po At Rn
132.9 137.3 138.9 178.5 181.0 183.8 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 (209) (210) (222)
87
7
88
89
104 105 106 107 108 109 110 111 112
Fr Ra Ac Rf Db Sg Bh Hs Mt Uun Uuu Uub
(223) 226.0 227.0 (261) (262) (263) (262) (265) (266) (269) (272) (277)
58
59
60
61
62
63
64
65
66
67
68
69
70
71
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
140.1 140.9 144.2 (145) 150.4 152.0 157.2 158.9 162.5 164.9 167.3 168.9 173.0 175.0
90
91
92
Th Pa U
93
94
95
96
97
98
99
100 101 102 103
Np Pu Am Cm Bk Cf Es Fm Md No Lr
232.0 231.0 238.0 237.0 (244) (243) (247) (247) (251) (252) (257) (258) (259) (260)
9