
Exam 3

Spring 2014/15
CHE 140
100 total points

100 points
Name: ____________________________
Section: 5701
Date: Mon. Apr. 6, 2015
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. If you do not show your work, you will receive
zero points and be very sad. The symbols to the left of each number indicate the chapter-concept
area-letter that the question is testing over. The last page of this exam has a periodic table which
you may rip off to use.
6-II-a,b
1. (1 point) If you have a gross of paper clips (a dozen dozens), how many do you have?
Now, if you have a mole of paper clips, how many do you have?
6-II-a,b 2.
6-III-a,b
(1 point) Complete the “roadmap” below by indicating what the missing terms from the
arrows are.
grams
moles
s
number of particles
1-IV-a,b 3.
1-V-a,b
1-VI-a,b,c,d,e
1-VII-a,b
3-II-a,c,d
3-III-b
6-II-b,c
(1.75 points) Say we have 7.609×1048 atoms of lead, how many moles of it do we have?
1-IV-a,b 4.
1-V-a,b
1-VI-a,b,c,d,e
1-VII-a,b
3-II-a,d
3-III-b
6-III-a,b
(2 points) Say we have 15.730 grams of nickel, how many moles of it do we have?
5. (2.25 points) How many gold atoms are found in 28.4 grams of gold?
1-IV-a,b
1-V-a,b
1-VI-a,b,c,d,e
1-VII-a,b
3-II-a,d
3-III-b
6-II-b,c
6-III-a,b CHE 140 Exam 3 S15.docx
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6. Answer the following questions about a 75.220 gram sample of Ca(CN)2.
1-IV-a,b a. (1.75 points) Please calculate its molar mass.
1-V-a,b
1-VI-a,b,c,d,e
1-VII-a,b
3-II-a,d
3-III-b
6-II-b,c
6-III-a,b
b. (1.75 points) How many moles of it do we have in this sample?
c. (2.25 points) What mass of carbon is contained in this sample?
7. Please answer the following questions.
3-II-c,d a. (3.75 points) Please write the balanced chemical reaction with states as described by the
following statements. The products are one mole of liquid water, one mole of carbon
5-III-b,c
5-IV-c,d
dioxide gas and two moles of aqueous potassium chloride. The reactants are one mole of
6-IV-a,b,c,d,e
solid potassium carbonate and two moles of aqueous hydrochloric acid. This is not an
equilibrium reaction.
b. (1 point) In the previous part, if we started with 1.529 grams of reactants and the final
solution was 1.210 grams, how much carbon dioxide gas was given off?
CHE 140 Exam 3 S15.docx
Page 2 of 8
8. (3 points) Balance the following chemical equations. Even though a “1” is normally
understood, please write a “1” on the blank if you need it to balance an equation.
3-II-a,d
5-III-a
6-IV-b,d
a. ____ S8(s) + ____ F2(g) → ____ SF6(s)
b. ____ C3H6(g) + ____ O2(g) → ____ CO2(g) + ____ H2O(g)
c. ____ NI3(s) → ____ N2(g) + ____ I2(g)
d. ____ N2(g) + ____ O2(g) → ____ NO(g)
e. ____ Na3PO4(aq) + ____Cu(NO3)2(aq) → ____ Cu3(PO4)2(s) + ____ NaNO3(aq)
f. ____ Cr2O3(s) + ____ H2(g) → ____ Cr(s) + ____H2O(g)
9. (3 points) Classify each of the reactions in the previous question as combination,
3-II-a,d decomposition, single replacement, double replacement, or combustion.
6-IV-b,d
6-V-a
a. ______________________________
d. ______________________________
b. ______________________________
e. ______________________________
c. ______________________________
f. ______________________________
10. (4 points) Complete and balance the following reactions. Be sure to include states.
3-II-a,c,d a. double replacement where the a solid is formed with the iodide
5-III-a,b,c
5-IV-c,d
6-IV-b,d,e
6-V-b
Pb(NO3)2(aq) +
NaI(aq) →
b. combustion
CH4(aq) +
O2(aq) →
11. (3 points) Multiple select: Which of the reactions in question 8 (reprinted here, still
unbalanced, for you) were redox reactions? Circle all that apply!
3-II-a,d
6-IV-b
6-VI-a,b,c
a. S8(s) + F2(g) → SF6(s)
b. C3H6(g) + O2(g) → CO2(g) + H2O(g)
c. NI3(s) → N2(g) + I2(g)
d. N2(g) + O2(g) → NO(g)
e. Na3PO4(aq) + Cu(NO3)2(aq) → Cu3(PO4)2(s) + NaNO3(aq)
f. Cr2O3(s) + H2(g) → Cr(s) + H2O(g)
12. (1.5 points) Short Answer:
6-IV-b a. If a chemical species loses electrons, was it oxidized or reduced?
6-V-b b. If the oxidation number on a species
6-VI-c,d
gets smaller, was it oxidized or reduced?
c. True or false, redox reactions are what powers batteries.
CHE 140 Exam 3 S15.docx
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13. (3.5 points) Complete the following for the balanced redox reaction below.
a. Write the oxidation number for each elemental symbol present above that symbol.
3-II-a,d
6-IV-b
6-VI-a,b,c
C5H12S(ℓ) + 9 O2(g)  5 CO2(g) + 6 H2O(g) + SO2(g)
b. Now, what…
gains electrons
is reduced
loses electrons
is oxidized
14. (2 points) Complete the following roadmap by drawing in the appropriate missing arrows
6-III-a,b and supplying the correct words for all the arrows to help you with your calculations.
6-VII-a
mass reactant
moles reactant
mass product
moles product
15. Answer the following questions given the balanced chemical equation below. Note that the
reaction is reprinted below each part in case that should prove useful.
2 Na3PO4(aq) + 3 CuCl2(aq) → Cu3(PO4)2(s) + 6 NaCl(aq)
a. (1.5 points) Without doing any calculations, if we start with three moles of CuCl2…
1-II-a,b
1-III-a,b
1-IV-a,b,c,d,e
1-V-a,b
3-II-a,d
3-III-b
6-III-a,b
6-IV-b,d
6-VII-a,b,c
How many moles of Na3PO4 do we need to completely use it up?
What is the maximum amount of moles of Cu3(PO4)2 could we make?
Now, if we have four moles of Na3PO4 and four moles of CuCl2,
what is the maximum amount of moles of Cu3(PO4)2 could we make?
b. (3.5 points) How much Cu3(PO4)2, in grams, can be obtained from 25.52 g of Na3PO4?
2 Na3PO4(aq) + 3 CuCl2(aq) → Cu3(PO4)2(s) + 6 NaCl(aq)
c. (5.75 points) Now, let’s say we try the reaction again. This time we start with 50.00 g of
Na3PO4 and 75.00 g of CuCl2. Now, what is the maximum mass of Cu3(PO4)2, in grams,
that can be obtained?
2 Na3PO4(aq) + 3 CuCl2(aq) → Cu3(PO4)2(s) + 6 NaCl(aq)
CHE 140 Exam 3 S15.docx
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1-IV-a,b 16.
1-V-a,b
1-VI-a,b,c,d,e
1-VII-a,b
6-IV-c
6-VII-a,b
(1.75 points) A particular scientist performs a reaction that has a theoretical yield of 52.1012
grams and obtains 52.0618 grams of product. What percent yield was obtained?
Diagram 1
17. (5 points) Answer the following questions about the diagrams 1 & 2.
6-VIII-a,b,c a. To properly label both diagrams, letter X should be
80
A
50
________________ and letter Y should be ________________.
b. Which letters best indicate the
ΔH for each of the reactions?
c. Which letters best indicate the activation
energy, Ea, for each of the reactions?
C
B
Y
10
X
Diagram 2
d. Which diagram is exothermic?
80
D
Which diagram is endothermic?
50
F
e. On diagram 2, what is the numerical value for ΔH? __________
Y
E
10
On diagram 1, what is the numerical value for for Ea? ________
1-II-a,b
1-III-a,b
1-IV-a,b,c,d,e
1-V-a,b
3-II-a,d
3-III-b
5-III-c
5-IV-c,d
6-III-a,b
6-IV-b,d
6-VII-a,b
6-VIII-a,b
7-II-a,b
7-III-a,c
X
18. (3 points) For the reaction shown below, how many kcal are produced when 32.0 g of CH4
react?
CH4(g) + 2 O2(g) → 2 H2O(g) + 218 kcal
a. 218 kcal
b. 109 kcal
c. 436 kcal
d. 6.81 kcal
e. 698 kcal
19. (2.25 points) True or False?
___________ a. Gas particles are always in motion and have elastic collisions.
___________ b. We can never use Celsius for temperature in gas law calculations.
___________ c. The volume of one mole of any gas is always 22.4 L.
7-II-a,b
7-III-c
20. (2.25 points) Look at the pictures of the balloons below and decide what the balloon would
look like under the described conditions.
__________ a. The pressure on the balloon is halved but
temperature is same.
__________ b. Half the air is let out and then the
temperature is doubled.
__________ c. The amount of air is doubled while the
temperature goes from 60 to 15 ºC.
CHE 140 Exam 3 S15.docx
initial
a.
b.
c.
d.
Page 5 of 8
7-II-a,b
7-III-c
21. (1.5 points) Fill in the blanks: The higher the speed of gas particles, the __________ kinetic
energy they possess, and the _____________ the temperature of the sample! The density of
this sample would _____________ if in a flexible container.
22. (2 points) Multiple choice: Which of the following is not a part of the kinetic theory of
7-II-a gases?
a. Gas particles neither attract nor repel one another.
b. There is very little empty space in a gas.
c. Gas particles move rapidly.
d. A gas is composed of very small particles.
e. Gas particles move faster as the temperature increases.
Note, if you do not know the answers to the next four questions, please ask! It is better to lose a few
points here than all of the calculation points coming up! If you think you know but just aren’t sure, write
what you think and have me check it – that will only cost you half the points if you are correct.
23. (1 point) What are STP conditions?
7-III-a
a. STP Temperature: __________
b. STP Pressure: __________
24. (1 point) Complete the following conversion factors, correctly:
7-III-b
a. 1 atm = __________ torr
b. 1 mmHg = __________ torr
25. (2 points) Please complete the following gas law equations started below:
7-III-c
a. Combined gas law:
7-III-c26.
n1

b. Ideal gas law:
=n
(1 point) What is the value of R, the gas constant (give units too)?
27. (2.75 points) How many grams of neon occupy a volume of 18.4 L at STP?
1-IV-a,b
1-V-a,b
1-VI-a,b,c,d,e
1-VII-a,b
3-II-a,c
6-II-a
7-III-a,b,c
1-IV-a,b
1-V-a,b
1-VI-a,b,c,d,e
1-VII-a,b
6-II-a
7-III-a,b,c
28. (3.5 points) Multiple choice: The temperature of a 500 mL sample of gas increases from
150 K to 77 ºC. What is the final volume of the sample of gas in liters, if the pressure in the
container is kept constant?
a. 9.5×10–6 L
b. 4.7×10–5 L
c. 0.21 L
d. 0.11 L
e. 1.17 L
CHE 140 Exam 3 S15.docx
Page 6 of 8
1-IV-a,b
1-V-a,b
1-VI-a,b,c,d,e
1-VII-a,b
6-II-a
7-III-a,b,c
1-IV-a,b,c
1-V-a,b
1-VI-a,b,c,d,e
1-VII-a,b
6-II-a
7-III-a,b,c
29. (4 points) At 1.03 atm and 21.2 ºC, a gas sample contains 5.55 moles. What is the final
pressure (in torr) if an additional 1.11 moles are added and the temperature changes to
89.4 ºC?
30. (4 points) A diver exhales a bubble with a volume of 360.8 mL at a pressure of 1,824 mmHg
and a temperature of 19.72 ºC. What is the volume of the bubble in L when it reaches the
surface where the pressure is 781.3 torr and the temperature is 25.64 ºC?
31. (4.75 points) Multiple choice: Determine the volume of H2S (at 102 ºC and 1.20 atm)
needed to produce 55.0 g of S. Assume that there is excess SO2 present.
2 H2S(g) + SO2(g) → 3 S(s) + 2 H2O(g)
a. 29.3 L
b. 34.1 L
c. 66.0 L
d. 44.0 L
e. 22.7 L
1-IV-a,b
1-V-a,b
1-VI-a,b,c,d,e
1-VII-a,b
6-II-a
7-III-a,b,c,d
32. (5 points) Select one of the essay questions below and answer in the space below.
a. Why is there less pressure at higher altitudes?
b. Since absolute zero is theoretical, how did we determine the value of it on the Celsius
scale?
7-II-a,b
7-III-c
33. (4 points) In class several gas laws demonstrations were performed. Choose one of the
demos and briefly describe it and what happened. Indicate what variables were involved in
the demo, be sure to say which one was independent. Also, tell if those variables were
directly or inversely related. Finally, draw a little graph to show their relationship properly.
7-III-c
CHE 140 Exam 3 S15.docx
Page 7 of 8
Table based on information obtained from http://www.chem.qmul.ac.uk/iupac/AtWt/ on 6/5/14.
CHE 140 Exam 3 S15.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
He
4.0026
IIA
H
2
1
1.008
VIIIA
IA