CHEM 108 (Fall-2006)
Exam. 1 – (Section 001) (103 pts)
Name: --------------------------------------------------------------------------, CLID # -------------------------------LAST NAME, First
(Circle the alphabet segment of your LAST NAME): A-B
C-F
G-L
M-O
P-Z
Please answer the following questions:
Part I: Multiple Choices (64 pts: 16 @ 4 pts each). Circle the ONE best answer:
1. Which of the following pairs is most likely to be heterogeneous?
a) methanol, CH3OH, and water, H2O
b) hexane, CH3(CH2)4CH3, and octane, CH3(CH2)6CH3
c) potassium chloride, KCl, and carbon tetrachloride, CCl4
d) acetic acid, CH3COOH, and water, H2O
2. Which statement is incorrect regarding the solubility of gases in liquids?
a) Henry’s law states that C = kP.
b) The solubility of a gas increases as the pressure increases.
c) Since the dissolving of gases is endothermic, increasing temperature leads to decreasing
solubility.
d) The Henry’s law constant, k differs for different gases and liquids.
3. Which of the following solutions has the highest boiling point?
a) 1.0 m glucose in water
b) 1.0 m NaCl in water
c) 1.0 m KNO3 in water
d) 1.0 m CaCl2 in water
4. What is the osmotic pressure, in atm, produced by a 20.0% glucose (C6H12O6, molar mass = 180
g/mol) solution (d = 1.08 g/mL) separated from pure water at 25 ºC?
a) 36.7
b) 30.6
c) 29.3
d) 32.2
5. The experimental data from a certain reaction gives these graphs. What is the most likely order of
this reaction?
a) zero
b) first
c) second
d) third
6. The reaction: A
B, the activation energy, Ea = 125 kJ/mol, and the heat of reaction ∆H˚
= + 50 kJ/mol. What is the Ea for the reverse reaction in kJ/mol?
a) 75
b) -75
c) 125
d) 175
1
7. When a solid NH4SH is placed in a close flask at 28º C, the solid dissociates according to the
equation:
NH4SH (s)
NH3 (g) + H2 (g)
The total pressure of the equilibrium mixture is 0.840 atm. Determine Kp at this temperature.
a) 0.147
b) 0.176
c) 0.648
d) 0.420
8. Which physical property is not true regarding solutions of nonvolatile solutes?
a) vapor pressure of the solution is lower.
b) boiling point of the solution is higher than that of pure solvent
c) osmotic pressure is produced by solvent in the more dilute solution toward the more
concentrated solution
d) all of the above are correct
9. What is the minimum mass of glycerol, C3H8O3, that must be dissolved in 100. g H2O to prevent
the solution from freezing at -15o C?
a) 74 g
b) 66 g
c) 7.4 g
d) 114
B is 5.0 min. How many minutes will it
10. The half-life time of the first order reaction A
take to reduce the concentration of A to 1/16 of the initial value?
a) 5.0
b) 25
c) 10.
d) 20
11. Which is not usually a factor in determining the rate of a reaction according to collision theory?
a)
b)
c)
d)
Orientation of the molecules that colloid
Kinetic energy of the molecules colloid
The temperature of the reaction mixture
The stability of the product
12. For the system: SnO2 (s) + 2 CO (g)
expression is
Sn (s) + 2 CO2 (g), the equilibrium constant
a) [Sn][CO2]2/[SnO2][CO]2
b) [SnO2][CO]2/[Sn][CO2]2
c) (PCO2)2/(PCO)2
d) PCO2/PCO
13. A 6.0 m H2SO4 solution has d = 1.34 g/mL. What is the mass percent of H2SO4 in this solution?
a) 56.1
b) 58.8
c) 37.0
d) no answer was given
14. Which plot would not yield the indicated data for the reaction A
a)
b)
c)
d)
Products?
ln [A] vs. t: rate constant for a first order reaction
1/[A] vs. t: rate constant for a second reaction
ln k vs. T (K): activation energy
non of the above
2
15. The solubility of O2 (g), in water at 25oC is 3.16 mL/100 g H2O when the gas pressure was
maintained at 1 atm. What pressure of O2 (g) would be required to produce a saturated solution
containing 10.9 mL/100 g H2O?
a) 4.45
b) 3.45
c) 0.290
d) 3.16
16. Some PCl5 (g) with a partial pressure of 0.500 atm is heated in a closed container and the
following equilibrium is obtained: PCl5 (g)
PCl3 (g) + Cl2 (g). The equilibrium pressure
of Cl2 is 0.254 atm. What is Kp for this reaction at this temperature?
a) 3.93
b) 1.00
c) 0.250
d) 0.262
_____________________________________________________________________________________
Part II (39 pts: 3 @ 13 pts each) Calculations: Show all work for full credit. Please express all
answers with proper units and correct number of significant figures.
1. Initial rate data were obtained for the following reaction:
H2 (g) + Cl2 (g)
Expt No.
1
2
3
4
2 HCl (g)
Initial [H2], M
Initial [Cl2], M
0.0020
0.0020
0.0015
0.0050
Initial Rate, M.s-1
2.5 x 10-3
1.3 x 10-3
1.3 x 10-3
0.5 x 10-3
0.0050
0.0025
0.0025
0.0010
a) What is the overall order of the reaction?
b) What is the rate law for the reaction?
c) What is the rate constant of the reaction?
a) Overall order =
b) Rate law =
c) k =
3
2. Nicotine, extracted from tobacco leaves, is a liquid completely miscible with water at temperature
below 60 °C. If a solution made by dissolving 1.921 g of nicotine in 48.92 g H2O starts to freeze at
–0.450°C. What must be the molar mass of nicotine? (Kf = 1.86°C/m for water).
MM =
3. Glycerin, C3H8O3 (92.1 g/mol), is a nonvolatile non-electrolyte with density of 1.26 g/mL at 25° C.
a) Calculate the vapor pressure at 25° C of a solution made by adding 50.0 mL of glycerin to 500.
mL of water. The vapor pressure of pure water at 25° C is 23.8 mmHg.
b) Calculate the osmotic pressure of the solution at 25° C.
Vapor pressure =
Osmotic pressure =
4
PREFERENCE SHEET FOR CHEM 108
Exam 1 – Spring 2006
You will have 55 minutes to complete this exam. The exam has 4 pages plus a reference page.
When you are told to do so, tear off the Periodic cover sheet and use as required during exam.
Constants & Useful Equation :
Gas Constant: R = 8.3145 J/K.mol = 8.3145 x 10-3 kJ/K.mol = 0.0821 L atm/mol.K
K = 273 + °C
1 atm = 760 torr = 760 mmHg
d (density) = mass (m)/volume (V)
Cg = k.Pg
ni = Pi/Pt
χ1.P1o
π = [C]RT
∆T = i. Km.
P1 =
Rate = k[A]
ln [A]o = kt
[A]
ln[A] = - kt + ln[A]o
Rate = k[A]2
1/[A] - 1/[A]o = kt
t1/2 = 1/k[A]o
Rate = k
[A] = - kt + [A]o
t1/2 = [A]o/2k
-Ea/RT
k = Ae
∆P1 =
PV = nRT
χ2.P1o
t1/2 = ln 2/k = 0.693/k
ln k = (-Ea/R)(1/T) + ln A
1
1
2
H
Periodic Table of the Elements
He
1.01
3
2
3
5
6
7
8
Li Be
B
C
N
O F
6.94 9.01
10.81 12.01 14.01 16.00 19.00 20.18
11
13
4
12
14
15
9
10
Ne
16
17
S
Cl Ar
18
Na Mg
Al Si P
22.99 24.30
26.98 28.08 30.97 32.06 35.45 39.95
19
4
4.00
20
21
22
23
K Ca Sc Ti V
24
25
26
27
28
29
30
31
32
33
34
35
36
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
39.1 40.08 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
37
5
6
38
39
Rb Sr Y
40
41
42
43
44
45
46
47
48
49
50
51
52
53
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I
54
Xe
85.47 87.62 88.91 91.22 92.91 95.94 (98)
101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.1
55
76
56
57
72
73
74
75
77
78
79
80
81
82
83
84
85
86
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
132.9 137.3 138.9 178.5 181.0 183.8 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 (209) (210) (222)
104 105 106 107 108 109 110 111 112
Fr Ra Ac Rf Db Sg Bh Hs Mt Uun Uuu Uub
(223) 226.0 227.0 (261) (262) (263) (262) (265) (266) (269) (272) (277)
87
7
88
89
58
59
60
61
62
63
64
65
66
67
68
69
70
71
Ce Pr Nd Pm Sm Eu Gd 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
Th Pa U
93
94
95
96
97
98
99
100 101 102 103
Np Pu Am Cm 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)
5
6
7