Chem 2000A Quiz 1 (A)
Jan 20th, 2003: 11:15 to 11.45 am
Your name _______________
Instructor: Dr. M. Gerken
Student ID _______________
Time: 30 min
No. of pages: 4
Report all your answers using significant figures. Show all units and their conversions throughout your
calculations.
Question 1 (5 Marks)
Which compounds do you expect to dissolve in CCl4? Explain your answer briefly.
(a) KF
KF won’t dissolve in CCl4 since KF is an ionic solid. Interactions between CCl4 and K+ and F- are not
strong enough to overcome the ionic forces in the solid.
(b) Xe
Xenon dissolves in CCl4 to a certain extent. Xenon as well as CCl4 are non-polar.
(c) hexane (C6H14)
Hexane will dissolve in CCl4 since both molecules are non-polar.
(d) ethanol (C2H5OH)
Ethanol will not dissolve in CCl4; ethanol is polar and forms hydrogen bonds while CCl4 is non-polar.
(e) SiO2
SiO2 will not dissolve in CCl4 since it is a network solid. For SiO2 to dissolve covalent bonds would have to
be broken, which does not occur.
Question 2 (5 Marks)
Which of the following statements are correct?
a) Henry’s law is valid for ideal solutions. (incorrect)
b) Raoult’s law is valid for ideal solutions. (correct)
c) In ideal solutions, no solute-solvent interactions are present. (incorrect)
d) In ideal solutions, solute-solvent interactions are of the same magnitude as solvent-solvent interactions.
(correct)
e) In ideal solutions, no solute-solute interactions are present. (incorrect)
1
Question 3 (4 Marks)
In each pair of solvents, which has a higher vapor pressure at room temperature? Explain your answer
briefly.
a)
H2O and CCl4
Carbon tetrachloride has a higher vapor pressure than water at room temperature, since the water
molecules in the liquid state form two hydrogen-bonds per molecule. The CCl4 molecules in the liquid state
exhibit London dispersion forces, thus can escape more easily in the gas phase than the water molecules.
b)
CF4 and CCl4
Both molecules exhibit only London dispersion forces in the liquid state due to their non-polar nature. Since
chlorine is more polarizable than fluorine the dispersion forces are significantly stronger in CCl4 than in
CF4. Therefore, CF4 has a much higher vapor pressure than CCl4 at room temperature.
Question 4 (8 Marks)
Which intermolecular forces are present in the solid state of the following molecules? In order to answer
this question, draw the Lewis structure for each of the molecules!
(a)
SiF4
..
:F :
..
Si F :
..
:F
.. : :F
..:
London dispersion forces (induced dipole-induced dipole)
CH3COOH (vinegar)
(b)
..
H O
..
:O
..
C
CH3
Hydrogen-bonding interactions and dispersion forces (induced dipole-induced dipole and
dipole-induced dipole interactions)
Propane CH3CH2CH3
(c)
H
H
H
C H
H C C
H
H
H
London dispersion forces (induced dipole-induced dipole)
2
(d)
1-octanol, CH3CH2CH2CH2CH2CH2CH2CH2OH
OH
dispersion forces (induced dipole-induced dipole and dipole-induced
dipole interactions) and hydrogen bonding interactions.
Question 5 (8 Marks)
Mercury (Hg) vapor is very toxic and liquid mercury should be kept in closed containers. What is the
minimum amount (in mL) of liquid mercury that has to be spilt to saturate the atmosphere of a laboratory of
1000. m3 with mercury vapor? The vapor pressure of mercury at 25 °C is 1.9 × 10-3 Torr.
ρ(Hg, 25 °C) = 13.534 g cm-3
pV = nRT
T= 25 °C = 298 K; V = 1000. m3; p = 1.9 × 10-3 Torr × 101325 Pa/(760 Torr) = 0.25 Pa
R = 8.314 J K-1mol-1
n(Hg) = pV/RT = 0.25 Pa × 1000. m3/(8.314 J K-1mol-1 × 298 K) = 0.10 Pa m3 J-1 mol
= 0.10 kg m-1 s-2 m3 kg-1 m-2 s2 mol = 0.10 mol
m(Hg) = 0.10 mol × 200.59 g mol-1 = 20 g
volume that the mercury vapor would have in the liquid state:
V(Hg(l)) = 20 g / (13.534 g cm-3) = 1.5 mL
The smallest amount of liquid mercury is 1.5 mL which if spilt results in an atmosphere saturate with
mercury vapor.
3
Fundamental Constants
Planck's constant, h 6.626 × 10-34 J s
Avogadro's number 6.022 × 1023 mol-1
Elementary charge (e) 1.6022 × 10-19 C
Electron mass
9.1095 × 10-28 g
Gas constant
8.314 J K-1mol-1
pV = nRT
0
p solv = X solv ⋅ p solv
Rydberg Constant
Proton mass
Neutron mass
Speed of light in vacuum, C
1.097 x 107 m-1
1.67252 × 10-24 g
1.6749 × 10-24 g
2.998 x 108 m s-1
S g = K H ⋅ pg
Physical quantity
Unit
Symbol
Definition
Frequency, f or ν
Energy , W or E
Force, F
Pressure, p
hertz
joule
newton
pascal
Hz
J
N
Pa
s-1
kg m2 s-2
J m-1 = kg m s-2
N m-2 = kg m-1 s-2
Temperature: 0 K = -273.15 °C; 0 °C = 273.15 K
Pressure: 1 atm = 760 Torr = 760 mmHg = 1.01325 bar = 101325 Pa; 1 bar = 105 Pa
Volume: 1 mL = 1 cm3; 1 L = 1000 cm3 = 1 dm3 = 0.001 m3
1
Chem 1000 Standard Periodic Table
18
1.0079
1H
4.0026
2He
hydrogen
2
13
14
15
16
17
helium
6.941
9.0122
10.811
12.011
14.0067
15.9994
18.9984
20.1797
3Li
4Be
5B
6C
7N
8O
9F
10Ne
11Na
12Mg
lithium berrylium
22.9898 24.3050
boron
26.9815
3
4
5
6
7
8
9
10
11
12
47.88
50.9415
51.9961
54.9380
55.847
58.9332
58.693
63.546
65.39
21Sc
22Ti
23V
24Cr
25Mn
26Fe
29Cu
30Zn
39Y
40Zr
41Nb
42Mo
43Tc
44Ru
72Hf
73Ta
74W
105Db
106Sg
107Bh
144.24
(145)
sodium magnesium
39.0983 40.078 44.9559
19K
20Ca
37Rb
38Sr
55Cs
56Ba
La-Lu
88Ra
Ac-Lr
potassium calcium scandium titanium vanadium chromium manganese
iron
87.62
88.9059 91.224 92.9064
95.94
85.4678
(98)
101.07
rubidium strontium
132.905 137.327
cesium
(223)
87Fr
francium
yttrium zirconium niobium
178.49 180.948
barium
226.025
molybdenum technetium
183.85
hafnnium tantalum tungsten
(262)
(263)
(261)
104Rf
rutherfordium
radium
140.115
140.908
57La
58Ce
59Pr
89Ac
90Th
lanthanum cerium
227.028 232.038
actinium9 thorium
28Ni
75Re
rhenium
(262)
76Os
14Si
15P
phosphorus
silicon
72.61
31Ga
32Ge
49In
50Sn
nickel
106.42
copper
107.868
zinc
112.411
45Rh
46Pd
47Ag
48Cd
78Pt
79Au
gold
mercury
thallium
81Tl
82Pb
157.25
158.925
162.50
164.930
167.26
66Dy
67Ho
dysprosium holmium
68Er
77Ir
osmium
(265)
iridium
(266)
108Hs
109Mt
150.36
151.965
platinum
80Hg
oxygen
32.066
16S
fluorine
35.4527
neon
39.948
17Cl
18Ar
74.9216
sulfur
78.96
chlorine
79.904
33As
34Se
35Br
51Sb
52Te
83Bi
gallium germanium arsenic selenium bromine
114.82 118.710 121.757 127.60 126.905
cobalt
102.906
tin
207.19
lead
antimony tellurium
208.980
(210)
53I
65Tb
231.036
238.029
237.048
(240)
(243)
(247)
terbium
(247)
91Pa
92U
93Np
94Pu
95Am
96Cm
97Bk
uranium neptunium plutonium americium curium
4
(251)
(252)
erbium
(257)
argon
83.80
36Kr
krypton
131.29
54Xe
iodine
(210)
xenon
(222)
84Po
85At
88Rn
168.934
173.04
174.967
69Tm
70Yb
71Lu
bismuth polonium astatine
hassium meitnerium
60Nd
61Pm
62Sm
63Eu
64Gd
praesodymium neodymium promethium samarium europium gadolinium
protactinium
nitrogen
30.9738
aluminum
69.723
ruthenium rhodium palladium silver cadmium indium
186.207
190.2
192.22
195.08 196.967 200.59 204.383
dubnium seaborgium bohrium
138.906
27Co
13Al
carbon
28.0855
thulium ytterbium lutetium
(258)
(260)
(259)
98Cf
99Es
100Fm 101Md
102No
103Lr
berkelium californium einsteinium fermium mendelevium nobelium lawrencium
radon