
Spring 2013/14
CHE 180
100 total points
Exam 1


100 points
Name: ____________________________
Section: 5701
Date: Thu., Feb. 13, 2014
Directions: Answer the following questions completely. For multiple choice questions, circle the
one best answer unless noted otherwise. If the question is a calculation, be sure to show all your
work (including all units) for full credit unless noted otherwise. If you do not show your work, you
will receive zero points and be very sad. Draw a heart at the top of the exam for a quarter point. The
symbols to the left of each number indicate the chapter-concept area-letter that the question is testing
over; concepts you’ll have to remember from CHE 170 have not been listed. The last page of this
exam has a periodic table which you may rip off to use. Point values may change if needed.
1. (2.5 points) Answer the following short answer or fill in the blank questions.
____________ a. On average, the typical student should expect to study eight hours per
week for just this course.
____________ b. Students who get 85 questions correct on the final earn an automatic “A”
in the course.
____________ c. If you forget your calculator on an exam day, it’s okay to use your cell
phone as a calculator.
____________ d. Virtual attendance counts the same as in-person attendance with regards
to participation points and opting out of the final exam.
____________ e. Homework turned in late receives no credit.
2. (5 points) Give the definitions for the following units of concentration. Be very specific!
For example, for density you wouldn’t just say g/mL, you would say g solution/mL solution.
12-II-a,b,c,d
a. Molarity
b. molality
c. mole fraction d. percent by
e. parts per
12-III-a
mass
billion
3. (1.5 points) Short Answer
a. What two things can we do to increase
the solubility of a gas in a liquid solvent?
b. What one thing can we do to increase the
solubility of a typical solid in a liquid solvent?
12-III-a,d
12-IV-a,b
4. (2.5 points) Fill in the blanks: Colligative properties are properties of ideal solutions that
12-III-a,d
12-VI-a,b,c
depend upon the ____________________ of the solute not its ____________________. In
these solutions we find that the ____________________and ____________________
decrease, the ____________________ increases, and osmosis is possible.
Che180 Exam 1 S14.docx
Page 1 of 8
5. (5 points) Modified Homework 12.14: We have a container with 80.0 g of KNO3 and 150.0
12-III-a,b,c,d g of water at 25ºC. At 25ºC, a maximum of 37 g of KNO3 per 100.0 g of water can dissolve.
At 40ºC 63 g of KNO3 per 100.0 g of water can dissolve. At 10ºC 20 g of KNO3 per 100.0 g
of water can dissolve.
a. Is the solution unsaturated, saturated or supersaturated at 25ºC?
b. If we heat the solution to 40ºC, what exactly would we see happen and is the solution
now unsaturated, saturated, or supersaturated?
c. If we cool the solution to 10ºC, what exactly would we see happen and is the solution
now unsaturated, saturated, or supersaturated?
d. Which of these temperatures had a homogenous solution, if any?
e. Which of these temperatures had a heterogeneous solution, if any?
12-III-a,b,c
6. (1.75 points) Matching: match the following terms with their one best description. Not all
descriptions will be used, but each term has a unique description.
_____ solvent
_____ unsaturated solution
_____ solute
_____ supersatured solution
_____ solution
_____ saturated solution
a)
b)
c)
d)
e)
f)
g)
h)
i)
present in the same amount
present in the lesser amount
present in the greater amount
surpasses the maximum amount
contains exactly the same amounts
contains less than the maximum amount
contains the maximum amount
a homogeneous mixture
a heterogeneous mixture
_____ suspension
7. (3.5 points) What is the percent by mass sugar, C12H22O11, in a solution if the mole fraction
of sugar is 0.0027?
12-II-a,b,c,d
12-III-a
Che180 Exam 1 S14.docx
Page 2 of 8
12-II-a,b,c,d
12-III-a
8. (3.5 points) Multiple Choice: An aqueous solution is 0.387 M in HCl. What is the molality
of the solution if the density is 1.23 g/mL?
a. 0.115 m
b. 0.387 m
c. 0.315 m
d. 0.411 m
e. 0.318 m
9. (3.5 points) If the concentration of potassium chloride in water is 113 ppm, what is the
Molarity of potassium chloride in water? The Molar mass of KCl is 74.55 g/mol; assume the
12-II-a,b,c,d
density of the solution is 1.00 g/mL.
12-III-a
solute and solvent separated
solute
separated
solvent
separated
Enthalpy
10. (4.5 points) Use the diagram on the right
to help you answer the following
12-V-a,b
questions.
a. Place the following terms onto the
diagram in the correct locations:
Hhydration, –Hlattice, and
Hsolute+solvent. Note there are terms
that are not given.
b. Is the Hsolution term positive or
solvent
together
solute
together
final solution
negative? _______________
c. Give one term that
is always endothermic.
d. This solution is not energetically favorable to form. So, why does this solution form?
12-III-a
12-IV-a,b
12-VI-a
11. (5 points) Answer one of the following essays:
a. Why does putting salt on icy or snowy roads melt the ice or snow?
b. The solubility of gases and solids in liquid solvents change in opposite directions with
temperature changes, why?
Che180 Exam 1 S14.docx
Page 3 of 8
12. (0.75 points) What are the following mathematical formulas? If you don’t know, ask! That
way you can do the calculations that follow.
12-VI-b,c
a. Raoult’s law or the change in vapor
pressure (give one or the other, no need to give both)
b. change in boiling point
c. change in freezing point
13. (2 points) Multiple choice: Choose the aqueous solution with the lowest vapor pressure.
These are all solutions of nonvolatile solutes and you should assume ideal van’t Hoff factors
12-II-b,d
where applicable.
12-IV-a,b
a. 0.060 m K2CO3
12-VI-b
b. 0.030 m LiC2H3O2
c. 0.120 m C2H6O2
d. 0.040 m (NH4)2SO4
e. All same
14. (2 points) Modified Homework 12.46: An aqueous CaCl2 solution has a vapor pressure of
81.6 mmHg at 50 ºC. The vapor pressure of pure water at this temperature is 92.6 mmHg.
Assuming ideal behavior for the solution, what is the mole fraction of the CaCl2?
12-II-d
12-IV-a,b
12-VI-b
12-II-b
12-VI-c
12-II-b
12-VI-c,d
15. (4.5 points) Multiple choice: Determine the freezing point of an ideal solution that contains
78.8 g of naphthalene (C10H8, MM = 128.16 g/mol) dissolved in 722 mL of benzene (D =
0.877 g/mL). Pure benzene has a melting point of 5.50ºC and a Kfp of 4.90ºC/m.
a. 4.76ºC
b. 4.17ºC
c. 1.68ºC
d. 1.33ºC
e. 0.74ºC
16. (4.5 points) What is the Molar mass of a compound if 6.21 grams is dissolved in 24.0 grams
of chloroform to form a solution that has a boiling point of 68.04ºC? The boiling point of
pure chloroform is 61.70º and the Kbp is 3.63ºC/m.
Che180 Exam 1 S14.docx
Page 4 of 8
17. (2.5 points) Fill in the blanks/Short answer
12-II-a,b
12-III-a,c
12-V-a
a. Changes in _________________ will change Molarity but not molality.
b. Even though both contain particles larger than found in solutions, a ________________
will eventually settle out over time, but a _________________ will not.
c. Will a polar or nonpolar solute always be soluble in water? ______________________
d. What state(s) of matter can solutions be created in? _____________________________
18. (2 points) We learned two ways to define equilibrium, please give both of these definitions.
14-II-a,c,d
14-II-a,b,c,d
14-III-d
19. (1.5 points) Fill in the blanks/Short answer.
a. If a reaction favors making products, the value of the Kc is _________________.
b. If the temperature of an endothermic reaction is decreased, the size of the equilibrium
constant does what? _________________
c. Does a small equilibrium constant imply that the reaction is very slow at producing
products? _________________
20. (1.5 points) Write the equilibrium constant, Kc, for the reaction shown below.
C(s) + H2O(g)
CO(g) + H2(g)
14-II-e
14-III-a,e
14-II-e
14-III-a,e
21. (2 points) Given the aqueous equilibrium expression shown below, write the complete
corresponding balanced chemical equation (with states).
[ H 2CO3 ][OH  ]2
Kc 
2
[CO3 ]
22. (3.5 points) Given the equilibrium expressions shown below, determine the equilibrium
14-II-e
constant for this reaction: Ni(OH)2(s) + 6 NH3(aq)
Ni(NH3)62+(aq) + 2 OH–(aq).
2+
–
14-III-a,f
Ni (aq) + 2 OH (aq)
Ni(OH)2(s)
K1 = 1.8×1015
2+
2+
Ni(NH3)6 (aq)
Ni (aq) + 6 NH3(aq) K2 = 5.6×108
a. 3.2×106
b. 1.0×1024
c. 3.1×10–7
d. 9.9×10–25
e. 1.8×10–9
Che180 Exam 1 S14.docx
Page 5 of 8
23. (4 points) The equilibrium constant, Kc, for the decomposition of NOCl is 3.9×10–3 at 300ºC.
12-II-a
A mixture contains the gases at the following concentrations: [NOCl] = 5.0×10–3 M, [NO] =
14-II-c,e
2.5×10–3 M, and [Cl2] = 2.0×10–3 M. Is the reaction at equilibrium at 300ºC? If not, which
14-III-a,b,c,f
direction does the reaction need to go to reach equilibrium?
2 NOCl(g)
2 NO(g) + Cl2(g)
So, Kc ____ Qc. Is system at equilibrium? _________ If not, it needs to shift? ___________
12-II-a
14-II-e
14-III-a,b,c,f
24. (4 points) An equilibrium mixture of SO3, SO2, and O2 at 1000 K contains the gases at the
following concentrations: [SO3] = 0.41 M, [SO2] = 0.032 M, and [O2] = 0.59 M. What is the
value of the equilibrium constant for the decomposition of SO3 at this temperature?
a. 3.6×10–3
b. 0.046
c. 2.8×102
d. 22
e. 2.9×10–4
25. (5.75 points) In the gas phase at 25 ºC, acetic acid exists in the equilibrium with itself as
shown below. Assume the initial acetic acid concentration is 5.4×10–4 M, and its dimer (the
12-II-a
14-III- a,b,c,f
product) has not yet formed What are the equilibrium concentrations? Note, the assumption
will fail here , so use the quadratic formula.
2 CH3CO2H(g)
(CH3CO2H)2(g)
Kc = 3.2×104
Che180 Exam 1 S14.docx
Page 6 of 8
26. (6.25 points) Calculate the equilibrium concentrations of reactants and product when 0.328
moles of CH2Cl2 are introduced into a 2.00 L flask at 350 K? Use your smarts here, not the
assumption or the quadratic!
2 CH2Cl2(g)
CH4(g) + CCl4(g)
Kc = 10.5 at 350 K
12-II-a
14-III- a,b,c,f
27. (6.75 points) If initially we have 1.00 mole of nitrogen and 0.500 moles of hydrogen in a
5.00 L container, what are the equilibrium concentrations of the reaction shown below?
Suggestion, use the assumption!
N2(g) + 3 H2(g)
2 NH3(g)
Kc= 0.040 @ 500ºC
12-II-a
14-II-e
14-III- a,b,c,f
28. (8 points) Which way will the equilbrium shift if the following stresses are applied on the
following reaction?
14-II-e
NH4Cl(s)
NH3(g) + HCl(g)
Hº = 268 kJ & Kc = 5.10×10–6 at 548 K
14-III-e
14-IV-a,b
_________ a. A lot of helium is pumped
into the container.
_________ b. The temperature goes up.
_________ e. The volume of the container is
increased.
_________ f. Some ammonia is removed.
_________ c. More NH4Cl is added.
_________ g. The catalyst is added.
_________ d. The pressure increases.
_________ h. Some HCl is added.
Che180 Exam 1 S14.docx
Page 7 of 8
Table based on information obtained from http://www.chem.qmul.iupac/AtWt/index.html on 2/20/09.
Che180 Exam 1 S14.docx
Page 8 of 8
IIIB
IVB
VB
VIB
VIIB
…
VIIIB
…
IB
IIB
IIIA
IVA
VA
VIA
VIIA
Mg
Na
Ba
Cs
La
57
88.9059
*varies by
sample origin
Pr
Ce
Nd
60
(268)
Db
105
Pa
Th
U
92
232.038 231.036 238.029
91
90
140.116 140.908 144.242
59
58
Rf
104
(267)
Ac
Ra
(226)
Fr
(223)
Ta
180.948
Hf
92.9064
Nb
41
73
178.49
Cr
24
Mn
25
Pu
(244)
Np
(237)
94
93
150.36
Ni
28
Pt
78
106.42
Pd
46
96
157.25
Gd
64
(276)
Mt
109
(243)
(247)
N
Si
Al
P
15
Ga
In
49
69.723
Sn
50
72.64
Ge
32
Sb
51
74.9216
As
33
26.9815 28.0855 30.9738
14
13
31
Au
79
112
113
204.383
Tl
81
114
207.2
Pb
82
115
208.980
Bi
83
116
(209)
Po
84
127.60
Te
52
78.96
Se
34
32.065
S
16
Dy
66
(280)
Ho
67
(285)
Er
68
(284)
Tm
69
(289)
Yb
70
(288)
Lu
71
(293)
Rg Uub Uut Uuq Uup Uuh
111
200.59
Hg
80
O
97
(247)
(251)
Cf
98
(252)
Es
99
101
(257)
(258)
Fm Md
100
(259)
No
102
(262)
Lr
103
158.925 162.500 164.930 167.259 168.934 173.054 174.967
Tb
65
(281)
Ds
110
Cd
48
65.38
Zn
30
C
F
9
Ne
10
Xe
54
83.798
Kr
36
39.948
Ar
18
(210)
At
85
(294)
Uuo
118
(222)
Rn
86
126.904 131.293
I
53
79.904
Br
35
35.453
Cl
17
12.0107 14.0067 15.9994 18.9984 20.1797
107.868 112.411 114.818 118.710 121.760
Ag
47
63.546
Cu
29
192.217 195.084 196.967
Ir
77
102.906
Rh
45
58.9332 58.6934
Co
27
Am Cm Bk
95
151.964
Eu
(145)
Pm Sm
(270)
Hs
108
190.23
Os
76
101.07
Ru
44
63
(272)
Bh
107
186.207
Re
75
(98)
Tc
43
55.845
Fe
26
62
61
(271)
Sg
106
183.84
W
74
95.96
Mo
42
50.9415 51.9961 54.9380
V
23
72
91.224
Zr
40
47.867
Ti
22
(227)
89
88
87
132.905 137.327 138.905
56
55
Y
Sr
87.62
Rb
85.4678
39
38
37
Sc
44.9559
Ca
40.078
K
21
20
39.0983
19
22.9898 24.3050
12
11
10.811
8
B
Be
9.0122
Li
6.941*
7
5
4
3
6
He
4.0026
IIA
H
2
1
1.0079
VIIIA
IA