Answers

CHEM 1014
Exam II
John II. Gelder
October 21, 1999
Name ________________________
TA's Name ________________________
Lab Section _______
INSTRUCTIONS:
1. This examination consists of a total of 6 different pages.
The last page includes a periodic table and some useful
information. All work should be done in this booklet.
2. PRINT your name, TA's name and your lab section
number now in the space at the top of this sheet. DO
NOT SEPARATE THESE PAGES . You will receive 2
points for knowing your TA’s name AND laboratory
section number in which you are officially enrolled.
3. Answer all questions that you can and whenever called
for show your work clearly. Your method of solving
problems should pattern the approach used in
lecture/discussion. You do not have to show your work
for the multiple choice (if any) or short answer
questions.
4. No credit will be awarded if your work is not shown in
problems 3, 6b and 6c.
5. Point values are shown next to the problem number.
6. Budget your time for each of the questions. Some
problems may have a low point value yet be very
challenging. If you do not recognize the solution to a
question quickly, skip it, and return to the question after
completing the easier problems.
7. Look through the exam before beginning; plan your
work; then begin.
8. Relax and do well.
Page 2 Page 3 Page 4 TOTAL
SCORES _____ _____ _____ ______
(34) (36) (30) (100)

CHEM 1014 EXAM I PAGE 2
(16) 1. Complete the following table with the missing information.
(2 extra credit points)
Symbol # protons # neutrons # electrons charge
107
46 Pd 2+ 46 61 44 2–
15
7 N 3– 7 8 10 –3
241
92 U 92 149 92 0
95
42 Mo 5+ 42 53 37 +5
(6) 2. Balance each of the following equations.
a) 4Ag(s) + 2H 2 S(g) + O 2 (g) → 2Ag 2 S(s) + 2H 2 O(l)
b) MnO 2 (s) + 4HCl(aq) → Cl 2 (g) + MnCl 2 (aq) + 2H 2 O(l)
(3) c) 4NH 3 (g) + 6NO(g) → 5N 2 (g) + 6H 2 O(g) BONUS: do not attempt until after
completing the exam!)
(12) 3. Write and balance the equation for each of the following.
a) A formation equation for CCl 4 (g).
2Cl 2 (g) + C(s) → CCl 4 (l)
b) Write the formation for P 2 O 5 (s).
P 4 (s) + 5O 2 (g) →
2P 2 O 5 (s)
c) A combustion reaction for hexane, C 7 H 14 (l).
2C 7 H 14 (l) + 21O 2 (g) → 14CO 2 (g) + 14H 2 O(l)

CHEM 1014 EXAM I PAGE 3
(24) 4. Calculate the mass, in grams, in each of the following;
a) 5.67 mol C 7 H 14
5.67 mol C 7 H 14 ⎝ ⎛ 98 g
1 mol ⎠ ⎞ = 556 g C 7H 14
b) 4.72 x 10 –6 mol NaCl
4.72 x 10 –6 mol NaCl
⎛58.5 g ⎞
⎝ 1 mol ⎠
= 2.76 x 10–4 g NaCl
c) an atom of Ag
⎛107.9 g Ag
⎝ 1 mol
⎞
⎠
⎝ ⎛ 1 mol
6.02 x 10 ⎠ ⎞
23 atom = 1.79 x 10–22 g per atom
d) 3.92 x 10 24 molecules Br 2 .
3.92 x 10 24 molecules Br
⎛ 1 mol ⎞
2 ⎝ 6.02 x 10 23 molecules ⎠ ⎝ ⎛ 160 g
1 ⎠ ⎞
mole
= 1042 g
(12) 5. Calculate the number of moles in each of the following;
a) 7.00 x 10 –2 grams P 2 O 5
7.00 x 10 –2 grams P 2 O 5 ⎝ ⎛ 1 mol
142 g ⎠ ⎞ = 4.93 x 10–4 mol
b) 8.15 x 10 21 atoms Na.
8.15 x 10 21 atoms Na
⎛ 1 mol
⎝ 6.02 x 10 23 atom
⎞
⎠
= 0.0135 mol

CHEM 1014 EXAM I PAGE 4
(18) 6. Calculate each of the following;
a) the number of fluorine atoms in one molecule of PF 5 .
5 atoms of F in one molecule of PF 5 .
b) the number of O atoms in 1 mol of O 2 .
⎛6.02 x 10 23 O 2 molecule
1 mol O 2 ⎝ 1 mol
= 1.20 x 10 24 atoms O
c) the number of N atoms in 2.5 mol of N 2 O 5 .
⎞
⎠
⎝ ⎛ 2 O atoms
1 O 2 molecule
⎠ ⎞
⎛6.02 x 10 23 N 2 O 5 molecule
2.5 mol N 2 O 5 ⎝ 1 mol
= 3.01 x 10 24 atoms N
d) the number of Cl atoms in 3.00 x 10 –5 grams CCl 4 .
⎞
⎠
⎝ ⎛ 2 N atoms
1 N 2 O 5 molecule
⎠ ⎞
3.00 x 10 –5 grams CCl 4 ⎝ ⎛ 1 mol
154 g CCl ⎠ ⎞
4 ⎝ ⎛ 6.02 x 10 23 CCl 4 molecule
⎠ ⎞
1 mol
⎛ 4 Cl atoms ⎞
⎝1 CCl 4 molecule ⎠
= 4.69 x 1017 atoms Cl
(12) 7. Given the equation for the preparation of phosphoric acid H 3 PO 4 ,
Calculate,
P 4 O 10 (s) + 6H 2 O(l) → 4H 3 PO 4 (aq)
a) the number of mol of water required to react with 2.5 mol of P 4 O 10 .
2.5 mol of P 4 O 10 ⎝ ⎛ 6 mol H 2 O
1 mol P ⎠ ⎞
4 O 10
= 15.0 mol H 2 O
b) the number of mol of water required to produce 0.0455 grams of H 3 PO 4 .
0.0455 grams of H 3 PO 4 ⎝ ⎛ 1 mol
98 g H ⎠ ⎞ ⎛ 6 mol H 2 O ⎞
3 PO 4 ⎝ 4 mol H 3 PO 4 ⎠
= 6.94 x 10 –4 mol
a) the number of grams of P 4 O 10 required to react with 45 g of H 2 O.
45 grams of H 2 O
⎝ ⎛ 1 mol
18 g H ⎠ ⎞
2 O ⎝ ⎛ 1 mol P 4 O 10
6 mol H ⎠ ⎞
2 O ⎝ ⎛ 284 g P 4 O 10
1 mol P ⎠ ⎞
4 O 10
= 118 mol

CHEM 1014 EXAM I PAGE 5
1
2
3
4
5
6
7
IA
1
H
1.008
3
Li
6.94
11
IIA
4
Be
9.01
12
Na Mg
22.99 24.30
19 20
K
Ca
39.10 40.08
37
Rb Sr
38
85.47 87.62
55 56
Cs
Ba
132.9 137.3
87 88
Fr
(223)
Ra
226.0
IIIA IVA VA VIA VIIA 4.00
5 6 7 8
B C N O F
9 10
Ne
10.81 12.01 14.01 16.00 19.00 20.18
13 14 15 16 17 18
IIIB IVB VB VIB VIIB VIII IB IIB 26.98 28.09 30.97 32.06 35.45 39.95
21 22 23 24 25 26 27 28 29
Sc Ti V Cr Mn Fe Co Ni Cu 30 31 32 33 34 35 36
Zn Ga Ge As Se Br Kr
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
39
Y Zr
40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
88.91 91.22 92.91 95.94 (98) 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3
57 72 73 74 76 77 78 79 81 82 83 84 85 86
La
Periodic Table of the Elements
Hf
Al
Si
P
S
Cl
VIIIA
2
Ta W Re 75
Os Ir Pt Au Hg 80
Tl Pb Bi Po At Rn
138.9 178.5 180.9 183.8 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 (209) (210)
89 104 105 106 107 108 109
Ac
227.0
Rf Db
Sg
Bh
Hs Mt
(261) (262) (263) (262) (265) (266)
He
Ar
(222)
Lanthanides
Actinides
58 59 60 61 62 63 64
Ce Pr Nd Pm Sm Eu Gd 65 66 67 68 69 70 71
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 93 94 95 96
Th Pa U Np Pu AmCm 97 98 99 100 101 102 103
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)
Useful Information
6.023 x 10 23
mol =
grams
molar mass