
Exam 1

Spring 2015/16
CHE 180
100 total points

100 points
Name: ____________________________
Section: 57P1
Date: Tue., Feb. 9, 2016
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. A star by your name above will earn you a
half 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) True or false?
____________ a. Your instructor prefers to be called “Miss Kaya.”
____________ b. Students can attend class virtually using Collaborate in Blackboard.
____________ c. The graded homework can be found on-line at Mastering Chemistry.
____________ d. The final exam will have the same format as the regular exams.
____________ e. There will be three regular exams (lowest score dropped) this semester.
2. (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. (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.
4. (3.5 points) What is the mole fraction of MgCl2 in an aqueous solution that is 11.04% by
mass MgCl2? The Molar mass of MgCl2 is 95.21 g/mol.
12-II-a,b,c,d
Che180 Exam 1 S16.docx
Page 1 of 8
5. (3.5 points) A solution is 0.0433 m LiF. What is the Molarity of the solution if the density is
1.10 g/mL?
12-II-a,b,c,d
a. 0.0441 M
b. 0.0390 M
c. 0.0519 M
d. 0.0476 M
e. 0.0417 M
6. (2.5 points) True or False?
12-II-a,b,c,d
12-III-a,b,c,d
12-III-a,b
____________ a. To calculate the mole fractions of a solution given its percent by mass,
we do not have to know the density of the solution.
____________ b. If two liquids mix to an appreciable extent to form a solution, they are
said to be immiscible.
____________ c. To increase the solubility of a gas in a liquid, we should decrease the
temperature.
____________ d. Solubility is the concentration of solute in equilibrium with undissolved
solute in a saturated solution.
____________ e. If two liquids mix completely in any proportion to form a solution, the
resulting solution is supersaturated.
7. (4.25 points) Similar to Homework 12.13: We have a container with 215 g of sugar and 75
12-III-a,b,c,d g of water at 45ºC; there is only liquid in the container. At 25ºC, a maximum of 210 g of
sugar per 100.0 g of water can dissolve. At 45ºC 250 g of sugar per 100.0 g of water can
dissolve. At 80ºC 365 g of sugar per 100.0 g of water can dissolve.
a. Is the initial solution unsaturated, saturated or supersaturated at 45ºC?
b. If we heat the solution to 80ºC, what exactly would we see happen and is the solution
now unsaturated, saturated or supersaturated?
c. If we suddenly cool the solution to 25ºC, what exactly would we see happen and is the
solution now unsaturated, saturated or supersaturated?
12-III-c
8. (1 point) Give any example of…
a. a solid homogenous mixture
b. a liquid heterogenous mixture
Che180 Exam 1 S16.docx
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12-III-a,b,c
9. (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.
_____ suspension
_____ solute
_____ supersaturated solution
_____ solvent
_____ unsaturated solution
_____ solution
a)
b)
c)
d)
e)
f)
g)
h)
i)
contains the maximum amount
contains less than the maximum amount
contains exactly the same amounts
surpasses the maximum amount
present in the lesser amount
present in the greater amount
present in the same amount
a homogeneous mixture
a heterogeneous mixture
_____ saturated solution
10. (5 points) Answer one of the following questions about solutions formed in liquid solvents:
a. Why do most solids become more soluble at higher temperatures?
12-III-a,d
12-IV-a,b
b. Why do gases become more soluble at higher pressures?
solute and solvent separated
solute
separated
solvent
separated
Enthalpy
11. (4.5 points) Use the diagram on the right to
help you answer the following questions.
12-V-a,b
a. Place the following terms onto the
diagram in the correct locations: Hsolute,
Hhydration, and Hsolute + Hsolvent. Note
there are terms that are not given.
b. What term is equal
to the –Hlattice term?
c. Is the making of this solution exothermic
solvent
together
solute
together
final solution
or endothermic?
d. Is entropy increased or decreased by making this solution?
12. (3 points) When we add a solute to a solvent, the boiling point _________________, the
12-VI-a,b,c
freezing point _________________, the vapor pressure _________________, and osmotic
pressure is created. Assuming creation of an ideal solution, these changes are depended upon
_________________ of the solute not the _________________ of the solute. This is all due
to __________________________________.
Che180 Exam 1 S16.docx
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13. (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
12-II-d
12-VI-c
12-II-d
12-IV-a,b
12-VI-b
12-II-b
12-VI-c
12-II-b
12-VI-c,d
14. (3 points) Multiple choice: Choose the aqueous solution with the highest boiling point.
These are all solutions of nonvolatile solutes and you should assume ideal van’t Hoff factors
where applicable.
a. 0.200 m C3H8O3
b. 0.050 m NaNO3
c. 0.100 m Li2SO4
d. 0.060 m Na3PO4
e. All same.
15. (3.25 points) Say that 1.341 moles of water and 1.059 moles of ethanol, CH3CH2OH, are
mixed at 25.0ºC. What is the equilibrium partial pressure of water vapor above the mixture?
The vapor pressure of pure water at 25.0ºC is 23.8 mmHg. Assume ideal behavior for the
solution.
16. (4 points) Multiple Choice: Calculate the freezing point of a solution of 500.0 g of ethylene
glycol (C2H6O2) dissolved in 500.0 g of water. The Kfp for water is 1.86 ºC/m. Assume ideal
behavior for the solution.
a. 30.0 ºC
b. –30.0 ºC
c. 115 ºC
d. –115 ºC
e. –1.86 ºC
17. (4.5 points) What is the Molar mass of a molecular compound if 6.21 grams is dissolved in
24.0 grams of chloroform to form a solution that has a boiling point of 68.04 ºC? The boiling
point of pure chloroform is 61.70 ºC and its Kbp is 3.63 ºC/m.
Che180 Exam 1 S16.docx
Page 4 of 8
14-II-a,b,c,d
14-III-a,c,d
14-IV-a,b
18. (2.5 points) Indicate whether the following statements are true or false.
____________ a. In a reaction at equilibrium containing solid reactants and gaseous
products, an increase in pressure will shift the equilibrium.
____________ b. Adding a catalyst to a reaction changes the value of the equilibrium
constant.
____________ c. If the temperature for an exothermic reaction is decreased, the
equilibrium will shift to make more products.
____________ d. If we plot concentration of products and reactants versus time and
concentrations are changing, we are in the kinetic region.
____________ e. Product favored reactions have very large equilibrium constants.
19. (2 points) Please give both of the definitions we learned for chemical equilibrium.
14-II-a,c,d
20. (1.5 points) Write the equilibrium constant, Kc, for the reaction shown below.
Ca2+(aq) + 2 HCO3–(aq)
CaCO3(s) + CO2(g) + H2O(ℓ)
14-II-e
14-III-a,e
14-II-e
14-III-a,e
21. (2 points) Given the equilibrium expression shown below, write the complete corresponding
balanced chemical equation (with states). Hint: you’ll need calcium carbonate.
Kc 
[CaCl2 ][CO2 ]
[ HCl ]2
22. (3 points) The equilibrium constant is given for one of the reactions below. Determine the
value of the missing equilibrium constant.
14-II-e
2 SO2(g) + O2(g)
2 SO3(g)
Kc = 1.7×106
14-III-a,f
SO3(g)
½ O2(g) + SO2(g)
Kc = ?
2
a. 3.4×10
b. 8.5
c. 1.3×103
d. 1.2×10–6
e. 7.7×10–4
12-II-a
14-II-e
14-III-a,b,c,f
23. (3.5 points) At a given temperature, an equilibrium mixture from the decomposition of SO3
contains the following concentrations of gases: 0.054 M SO3, 0.00470 M SO2 and 0.58 M
O2. What is the value of the equilibrium constant for the reaction?
Che180 Exam 1 S16.docx
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12-II-a
14-II-c,e
14-III-a,b,c,f
24. (5 points) The reaction below is done at 300 ºC.
2 NOCl(g)
2 NO(g) + Cl2(g)
K = 3.9×10–3
Assuming constant temperature, are the reaction mixtures at equilibrium in the cases below?
If not which way will the reaction proceed?
a. [NOCl] = 5.0×10–3 M, [NO] = 2.5×10–3
b. [NOCl] = 0.0673 M, [NO] = 0.0328
M, and [Cl2] = 2.0×10–3 M.
M, and [Cl2] = 0.0164 M.
So, Kc ____ Qc.
Thus, reaction will (circle one):
shift left, stay the same, shift right.
So, Kc ____ Qc.
Thus, reaction will (circle one):
shift left, stay the same, shift right.
25. (6.25 points) Say that 8.72 moles of PCl5 are placed in a 3.50 L flask. After reaching
equilibrium, what are the concentrations of the reactants and products? Note, the assumption
will fail here , so use the quadratic formula.
PCl5(g)
PCl3(g) + Cl2(g)
Kc = 0.47
12-II-a
14-III- a,b,c,f
26. (6.25 points) Calculate the equilibrium concentrations of reactants and product when 0.724
moles of hydrogen and 0.724 moles of iodine are introduced into a 2.50 L flask at 698 K.
Use your smarts here, not the assumption or the quadratic!
H2(g) + I2(g)
2 HI (g)
Kc = 55.6 @ 698 K
12-II-a
14-III- a,b,c,f
Che180 Exam 1 S16.docx
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27. (6.5 points) At 300ºC, the Kc for the reaction below is 1.6×10–10. If we start with 0.704 M
SO3, what are the equilibrium concentrations? Suggestion, use the assumption, even if it
fails!
2 SO3(g)
2 SO2(g) + O2(g)
12-II-a
14-II-e
14-III- a,b,c,f
14-II-e
14-III-e
14-IV-a,b
28. (8 points) Assume that the chemical reaction below is at equilibrium. Now, what will happen
to the equilibrium if…
C(s) + H2O(g)
H2(g) + CO(g)
Hº = 131.3 kJ
________ a. The temperature decreases.
________ e. Some H2O(g) escapes.
________ b. Some C(s) is removed.
________ f. Room light is turned off.
________ c. The container size shrinks.
________ g. Some CO(g) is removed.
________ d. Some argon gas is added.
________ h. A catalyst is added.
29. (up to 5 ec points) Did you work one of the old tests that were available for this exam? Be truthful in your
reply as the instructor will confirm your answer and adjust the points for the question accordingly.
a. Yes! It was a great tool to prepare me for this test (even if I couldn’t sit and take in one sitting).
b. Sort of. I printed it out and went over it, but I didn’t answer all of the questions.
c. Not really. I printed it and turned it in just to try and get the extra credit.
d. No. I did not utilize.
Che180 Exam 1 S16.docx
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Table based on information obtained from http://www.chem.qmul.ac.uk/iupac/AtWt/ on 6/5/14.
Che180 Exam 1 S16.docx
Page 8 of 8
IIIB
IVB
VB
VIB
VIIB
…
VIIIB
…
IB
IIB
IIIA
IVA
VA
VIA
VIIA
Ba
Cs
La
57
88.9058
( ) mass number
for longest-lived
isotope when no
stable nuclides
Italicized values
vary based on
sample origin
Pr
Ce
Nd
60
(270)
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
(243)
Cd
48
65.38
Zn
30
96
157.25
Gd
64
(276)
Mt
109
(247)
Si
Sn
50
72.631
Ge
32
28.085
Sb
51
74.9216
As
33
30.9738
P
15
Au
79
Hg
80
Dy
66
(282)
Rg
111
113
Ho
67
(285)
Er
68
(285)
Cn Uut
112
204.38
Tl
81
Tm
69
(289)
Fl
114
207.2
Pb
82
116
(209)
Po
84
127.60
Te
52
78.972
Se
34
32.06
S
16
97
(247)
(251)
Cf
98
(252)
Es
99
101
(257)
(258)
Fm Md
100
Ne
10
Xe
54
83.798
Kr
36
39.948
Ar
18
117
(210)
At
85
118
(222)
Rn
86
126.904 131.294
I
53
79.904
Br
35
35.45
Cl
17
18.9984 20.1798
F
9
Yb
70
(288)
Lu
71
(293)
(259)
No
102
(262)
Lr
103
(294)
(294)
Uup Lv Uus Uuo
115
208.980
Bi
83
O
15.999
158.925 162.500 164.930 167.259 168.934 173.055 174.967
Tb
65
(281)
Ds
110
In
49
69.723
Ga
31
26.9815
14
N
14.007
107.868 112.414 114.818 118.711 121.760
Ag
47
63.546
Cu
29
192.217 195.085 196.967 200.592
Ir
77
102.906
Rh
45
58.9332 58.6934
Co
27
Am Cm Bk
95
151.964
Eu
(145)
Pm Sm
(277)
Hs
108
190.23
Os
76
101.07
Ru
44
63
(270)
Bh
107
186.207
Re
75
(97)
Tc
43
55.845
Fe
26
62
61
(271)
Sg
106
183.84
W
74
95.95
Mo
42
50.9415 51.9961 54.9380
V
23
72
91.224
Zr
40
47.867
Ti
22
(227)
89
88
87
132.905 137.328 138.905
56
55
Y
Sr
87.62
Rb
85.4678
39
38
37
Sc
44.9559
Ca
40.078
K
39.0983
21
20
19
Al
Mg
24.305
Na
22.9898
13
12
11
C
12.011
8
B
10.81
Be
9.0122
Li
6.94
7
5
4
3
6
4.0026
IIA
1.008
2
He
1
H
VIIIA
IA