HOUR EXAM I
CHEM 103 SEPTEMBER 26 2001
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NAME:__KEY____________________________
EXAM I
SEPTEMBER 26 2001
CH 103
DIRECTIONS
• There is only one correct answer to each question unless otherwise noted. Any questions for which more than one response
has been selected will not be counted.
• Your score is based solely on the number of questions you answer correctly. It is to your advantage to answer every
question.
• The best strategy is to arrive at your own answer to a question before looking at the choices. Otherwise, you may be misled
by plausible, but incorrect, responses.
IF YOU FIND YOURSELF BAULKED BECAUSE THERE IS A PIECE OF INFORMATION YOU DON’T HAVE,
RAISE YOUR HAND. YOU MAY BE ABLE TO BUY THE INFORMATION FOR A POINT.
TAKE A DEEP BREATH AND LET YOUR EYES FOCUS.
RELAX YOUR SHOULDERS
YOU KNOW MORE THAN YOU THINK YOU DO!
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HOUR EXAM I
CHEM 103 SEPTEMBER 26 2001
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NAME:__KEY____________________________
INORGANIC NOMENCLATURE:
1. Name, by IUPAC rules, the following compounds:
a. PF3
___________Phosphorus trichloride_
b. MgCl2
_______Magnesium chloride_______
c. Ca3(PO4)2
_____Calcium phosphate______
d. FeI2 _____iron (II) iodide or ferrous iodide
e.
NO2
___nitrogen dioxide______________
5 pts: ____
2. Give formulae for the following compounds:
a. Water: ____H2O__________________________
b. Sulfur trioxide: ____SO3_________________
c. Cobalt (III) sulfate: __Co2(SO4)3__________
d. Lithium hydroxide: __LiOH_______________
e. Sodium bromide:
___NaBr_____________
5 pts: ____
MULTIPLE CHOICE PORTION (Each question is weighted at 5 points):
3. A nitrogen monoxide molecule was produced at a synapse in you brain and is ambling
across the synaptic cleft at 50 cm/sec. The kinetic energy of the nitrogen monoxide
molecule in Joules is:
Atomic Mass of N: 14.0 g/mole
Atomic mass of O: 16.0 g/mole
A
B
C
D
E
2
WATCH THE UNITS!
2
6.23E-20 gcm /sec
2
2
6.23E-27 kgm /sec
2
3
6.20E-52 kgm /sec
2
4
37500 kgm /sec
None of the above
KE = ½ mv2 MW NO = 30.0 g/mol.
mass 1 NO = (30 g/mol)(1 mol/6.022 x 1023 molecules)(1kg/1000g) = 4.98 e-26 kg
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HOUR EXAM I
CHEM 103 SEPTEMBER 26 2001
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v = 50 cm/sec(1 m/100 cm) = 0.50 m
NAME:__KEY____________________________
4. An -particle is a helium nucleus, 4He2. The mass of a 4He2 nucleus is::
A
B
C
D
E
5.465E-30 kg
6.700E-27 kg
1.005E-26 kg
4.003 kg
None of the above
add up mass of 2 protons + 2 neutrons.
Bonus: What is the charge, in coulombs, of the 4He2 nucleus?
+ 2(1.602e-19 coulombs)
5. The force of electrostatic attraction, in Newtons, between a single magnesium ion and a
single chloride ion, separated by a distance of 0.60 nm, is:
WATCH THE UNITS!
Cl- has a charge of - 1.602 x 10-19 coulombs.
Mg2+has a charge of + 3.204 x 10-19 coulombs.
A
B
C
D
E
3
4.9964E+28 kg m/sec
4
-1.2823E-27 kg m/sec
5
-7.6937E-19 kg m/sec
2
-1.2823E-09 kg m/sec
None of the above
6. Which is true about the following three isotopes:
a.
b.
c.
d.
e.
f.
g.


, , and


They contain 119, 121 and 128 neutrons respectively;
They contain 43, 45 and 52 protons, respectively;
Because they are isotopes, they are all radioactive;
They are the elements Thallium, Bismuth and Thorium, respectively.
They are all the element strontium;
b and c are correct;
b and e are correct.
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HOUR EXAM I
CHEM 103 SEPTEMBER 26 2001
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NAME:__KEY____________________________
7. Which pair of ions is isoelectronic (has the same total number of electrons):
a. F- and Brb. S2- and Se2- ;
c. Ba2+ and Xe;
d. Fe2+ and Fe3+
BONUS:
Consider these three isotopes of Rhodium:
are unstable, that is, radioactive, because:
103Rh45
,
104RH45 , 105Rh45. 104Rh45
and
105Rh45
a) Their n/p ratio is too high;
b) Their p/n ratio is too high;
c) Their e-/p ratio is too low.
d) They have a lousy price/earnings ratio.
8. The correct Lewis structure for the sulfide ion is:
a)
b)
c)
d)
e)
4 pairs of valence e-, 2- charge
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CHEM 103 SEPTEMBER 26 2001
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NAME:__KEY____________________________
9. The mass of one atom of Rhodium is 1.7088 x 10-22 g. The density of Rhodium is 12.41
g/cm3.
The volume of the Rh atom is:
A
7.262E+22 mL
B
8.292 mL
C
2.121E-21 mL
D
1.377E-23 mL
E None of the above
1.7e-22g(1 cm3/12.41g)(1 mL/1cm3) =
10. The mass of an atom is mostly determined by:
a) the mass of protons ;
b) The mass of e- ;
c) the mass of neutrons;
d) the mass of protons + electrons.
e) The mass of protons + neutrons.
11. A covalent bond is best described as:
a) The complete transfer of a pair of e- between two atoms;
b) The complete transfer of a single e- between two atoms;
c) The sharing of a single e- between two atoms;
d) When an electron falls into the nucleus of another atom.
e) The sharing of a pair of e- between two atoms;
Key words are “sharing” and “pair’
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CHEM 103 SEPTEMBER 26 2001
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12.
NAME:__KEY____________________________
An ionic bond is best described as:
a) The complete transfer of a pair of e- between two atoms;
b) The complete transfer of one or more e- between two atoms;
c) The sharing of a single e- between two atoms;
d) When an electron falls into the nucleus of another atom.
e) The sharing of a pair of e- between two atoms;
13. The correct Lewis structure for Hydrocyanic acid (HCN) is: H C triple bond N lone pair
a)
b)
c)
d)
e)
14. The best definition for electronegativity is:
a) Electronegativity is the measure of the tendency of a combined atom to attract a shared
pair of electrons to itself; elements in the upper right hand side of the periodic table tend
to be more electronegative.
b) Electronegativity is the measure of the tendency of a combined atom to attract a shared pair
of electrons to itself; elements in the lower left hand side of the periodic table tend to be more
electronegative.
c) Electronegativity is the measure of the tendency of a combined atom to repel a shared pair
of electrons; elements in the lower left hand side of the periodic table tend to be more
electronegative.
d) Electronegativity is the measure of the tendency of a isolated atom to attract a single
electron; elements in the upper right hand side of the periodic table tend to be more
electronegative.
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HOUR EXAM I
CHEM 103 SEPTEMBER 26 2001
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15. In the water molecule (H2O), which of the following is true?
A. The electrons in the O-H bond spend more time near O than H;
B. The electrons in the O-H bond are equally shared by O and H;
C. The electrons in the O-H bond spend more time near H than O;
D. The O-H bond is ionic.
16. Atoms in Group I (the Alkali metals) of the periodic table:
a) Tend to lose a single valence electron;
b) Tend to gain a valence electron;
c) Have filled valence shells;
d) Are completely inert in water.
17.
Salicylic acid occurs in wintergreen leaves and in the bark of willow and birch. It is an
analgesic (Pain-killer) and anti-pyretic (Fever reducer) It has the following composition:
Elemental Analysis
C
H
O
60.87 %
4.38 %
34.75 %
Atomic Weight
12.011 g/mol
1.008 g/mol
16.00 g/mol
What is the chemical formula of salicylic acid?
A
C61H4O35
B
C5.1H4.3O2.2
C
C2.3H2O1
D
E
C7H6O3
None of the above
60.87 g C (1 mole C/12.011g) = moles C
4.38 g H (1 mole H/1.008 g) = moles H
34.75 g O (1 mole O/16.00 g) = moles O
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CHEM 103 SEPTEMBER 26 2001
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divide each mole by smallest # moles and multiply by 3 to get whole #
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HOUR EXAM I
CHEM 103 SEPTEMBER 26 2001
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17.
NAME:__KEY____________________________
How many μmoles of O2 are needed to produce 100.0 μmol of H2O?
2CH3OH + 3O2  4H2O + 2CO2
(A) 75.0 μmol
(C) 100.0 μmol
(B) 133 μmol
(D) 300.0 μmol
100 umol H2O(3O2 /4 H2O) =
Bonus: How many grams is 100 μmol of H2O? (MW = 18.0 g.mol)
100 umole H2O (10 e-6 mol/umol)(18 g/mol) = 1.8 e-3 g
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CHEM 103 SEPTEMBER 26 2001
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NAME:__KEY____________________________
18. Suppose you climb Mt Mansfield and are weather-bound by an early snow storm. You
happen to have picked up a butane lighter which some litter-bug dropped by the side of the
trail. You use it to light a fire::
2C4H10(l) + 10O2(g)  8CO2(g) + 4H2O(l)
If you burn 10.00 grams of butane in 5.0 grams of oxygen, which is the limiting reagent and
how many grams of carbon dioxide will you produce?
MW butane
MW O2
MW CO2
MW H2O
= 58 g/mol
= 32 g/mol
= 44 g/mol
= 18 g/mol
LIMITING REAGENT:
10 g Bu (1 mole/58 g) = 0.17 mole (10 O2/2 Bu) = 0.862 mol O2
needed.
5 g O2 (1 mol/32 g) = 0.16 mol O2 . Not enough O2 LR
(A) Butane (B) Oxygen
(C) Carbon dioxide
(D) Water
Grams Carbon dioxide produced:
A. 30 g
B. 10 g
C . 5.5 g
D. 2.8 E-3 g
E. None of the above
Use the LR:
0.16 mol O2(8 CO2/10 O2) = 0.125 mol CO2
0.125 mol CO2(44 g/mol) =5.5 g
BONUS: There are 92 folk registered in Ch 103 at SMC. How many moles is this?
92 folk(1mole/6.022e23 folk) = 1.528e-22 mol
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HOUR EXAM I
CHEM 103 SEPTEMBER 26 2001
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NAME:__KEY____________________________
19. How many grams of iron(III) sulfide is produced from the reaction of 0.2000 g of iron(III)
nitrate with excess sodium sulfide?
2Fe(NO3)3(aq) + 3Na2S(aq)  Fe2S3(s) + 6NaNO3(aq)
Molar Masses
Fe2S3
208 g·mol–1
Fe(NO3)3 242 g·mol–1
A
B
C
D
E
4.132E-04 g
8.264E-04 g
8.595E-02 g
3.438E-01 g
None of the Above
Fe(NO3)3 is LR (It says so in the problem)
0.2 g Fe(NO3)3(1 mol Fe(NO3)3/242 g)(1 Fe2S3/2Fe(NO3)3)(208 g/molFe2S3)
20. You react 0.6126 g of Potassium Hydrogen Phthalate (KHP)
with exactly 32.51 mL of NaOH:
MW KHP = 204.2 g/mol
MW NaOH = 40 g/mol
MW KP- = 203.2 g/mol
MW H2O = 18 g/mol
MW Na+ = 23 g/mol
KHP + NaOH  KP- + H2O + Na+
How many moles of KHP reacted?
A
6.126E-01 moles
B
1.251E+02 moles
C
3.000E-03 moles
D
2.042E+02 moles
E None of the above
0.6126 g KHP (1 mole KHP/204.2 g)
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CHEM 103 SEPTEMBER 26 2001
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21. A peptide (amide) bond may be represented as:
(A) only structure I is correct.
(B) only structure 2 is correct.
(C) the molecule flips rapidly back & forth between structure I & structure II.
(D) The  electrons are being shared between the N-C-O atoms. They are “delocalized”.
********************************************
21. SHORT ANSWER:
Draw the Lewis structure of the carbonate ion. Predict its 3-D shape.
Include any resonance contributors.
See homework key, C 2!!
Klaque’s Bonus: Calculate the mass, in grams, of one atom of Einsteinium (Es). Atomic wt =
254 g/mole.
254 g/mole Es(1 mole/6.022 e23 atoms) = 4.22 e -22 g
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CHEM 103 SEPTEMBER 26 2001
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END OF EXAM!
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CHEM 103 SEPTEMBER 26 2001
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SPECIAL UNITS & CONVERSION FACTORS
Acceleration due to gravity (g)
Avogadro’s number
Bohr radius
Boltzmann’s constant
Electronic charge-to-mass ratio
Elementary charge
Faraday constant
Gravitational constant (Universal)
Mass of an electron
Mass of a neutron
Mass of a proton
Molar volume of an ideal gas @ STP
Permittivity of vacuum
Planck’s constant
Rydberg constant
Speed of light in vacuo
Universal gas constant
Arrhenius Equarton
g
No
ao
kB
-e/me
e
F
G
me
Mn
Mp
Vm
εo
h
R∞
c
R
9.80665 m/sec2
6.0221367 x 1023 particles/mol
0.529177249 x 10-10 m
1.380658 x 10-23 J/K
1.75881962 x 1011 C/kg
1.60217733 x 10-19 C
9.6485309 x 104 C/mol
6.67259 x 10-11 m3/kg sec2
9.1093897 x 10-31 kg
1.6749286 x 10-27 kg
1.6726231 x 10-27 kg
22.41410 L/mol
8.854187817 x 10-12 C2/N m2
6.6260755 x 10-27 J sec
2.1798741 x 10-18 J
2.99792458 x 108 m/sec
8.314510 J/mol K
0.08205783 L atm/K mol
k = Ae-Eact/RT
Fgrav = -Gm1m2/r2
Felectrostatic = - [1/4πεo] q1 q2/r2
1 N = 1 kgm/sec2
1 J = 1 Nm = 1 kg m2/sec2
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CHEM 103 SEPTEMBER 26 2001
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NAME:__KEY____________________________
PERIODIC TABLE OF THE ELEMENTS
1A
1
H
8A
2
He
3
Li
2A
4
Be
3A
5
B
4A
6
C
5A
7
N
6A
8
O
7A
9
F
6.941
9.012
10.81
12.01
14.01
16.00
19.00
20.18
11
Na
12
Mg
5B
6B
7B
15
P
16
S
17
Cl
18
Ar
24.31
4B
14
Si
22.99
3B
13
Al
19
K
20
Ca
21
Sc
22
Ti
23
V
24
Cr
25
Mn
26
Fe
27
Co
39.10
40.08
44.96
47.88
50.94
52.00
54.94
55.85
37
Rb
38
Sr
39
Y
40
Zr
41
Nb
42
Mo
43
Tc
44
Ru
85.47
87.62
88.91
91.22
92.91
95.94
(98)
55
Cs
56
Ba
57
La
72
Hf
73
Ta
74
W
75
Re
132.9
137.3
138.9
178.5
181.0
183.8
87
Fr
88
Ra
89
Ac
104
Unq
105
Unp
106
Unh
(223)
226.0
227.0
(261)
(262)
58
Ce
59
Pr
140.1
90
Th
232.0
1.008
10
Ne
1B
2B
26.98
28.09
30.97
32.07
35.45
39.95
28
Ni
29
Cu
30
Zn
31
Ga
32
Ge
33
As
34
Se
35
Br
36
Kr
58.93
58.69
63.55
65.39
69.72
72.61
74.92
78.96
79.90
83.80
45
Rh
46
Pd
47
Ag
48
Cd
49
In
50
Sn
51
Sb
52
Te
53
I
54
Xe
101.1
102.9
106.4
107.9
112.4
114.8
118.7
121.8
127.6
126.9
131.3
76
Os
77
Ir
78
Pt
79
Au
80
Hg
81
Tl
82
Pb
83
Bi
84
Po
85
At
86
Rn
186.2
190.2
192.2
195.1
197.0
200.6
204.4
207.2
209.0
(209)
(210)
(222)
107
Uns
108
Uno
109
Une
(263)
(262)
(265)
(266)
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
71
Lu
140.9
144.2
(145)
150.4
152.0
157.3
158.9
162.5
164.9
167.3
168.9
173.0
175.0
91
Pa
92
U
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
103
Lr
231.0
238.0
237.0
(244)
(243)
(247)
(247)
(251)
(252)
(257)
(258)
(259)
(260)
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8B
4.003
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