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Chem 112
SAMPLE FINAL EXAM
Name (Printed):
Section:
Instructions: This test is closed book and closed notes. You may use an 8½"×11" sheet with
formulas prepared beforehand. Calculators are also allowed, although preprepared programs,
integration and equation solving routines are not. Credit is dependent on showing all steps in the
calculation on this test. Clearly state any assumptions or approximations you use to solve the
problems. If an approximate solution is appropriate, successive approximations are not required.
For full credit, an answer must have the correct number of significant figures and correct units.
(16 problems, 200 pts)
R = 8.31441 J/K-mol
= 0.08206 L-atm/K-mol
1 atm = 760 Torr
= 1.01325105 Pa
0 C = 273.15 K
23
-1
NA = 6.02210 mol
F = 96,485 C-mol-1
1 J = 1 V-C
Kw = 1.0010-14
1 m = 100 cm = 1000 mm = 106 m = 109 nm = 1010 Å
density of water  = 1.00 g/ml = 1.00 kg/L
if ax 2  bx  c  0 , then x 
b  b 2  4ac
2a
H
C
N
O
Ca
Atomic Weights (g/mol)
= 1.01
Na = 22.99
= 12.01
Cl = 35.45
= 14.01
P = 30.97
= 16.00
Br = 79.9
= 40.08
Pb = 207.2
CHEM 112 – Sample Final Exam
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CHEM 112 – Sample Final Exam
1
2
/5
11
/15
/10
12
/15
3
/15
13
/15
4
5
/20
14
/15
6
/5
15
/10
3/17
7
/5
16
/15
/15
8
/15
9
/10
10
/15
total
/200
CHEM 112 – Sample Final Exam
4/17
1) Circle the pair with the best solubility.
(3 right = 5 pts, 2 right = 3 pts, 1 right = 1 pt, 0 right = 0 pt).
a. Ca(NO3)2 and water
versus
Ca(NO3)2 and CCl4.
b. CH3–CO–CH3 and benzene (C6H6)
versus
CH3–CO–CH3 and CH3OH
c. HF and hexane (C6H14)
versus
HF and CH3CN
2) Find the oxidation number for the indicated atom in each compound (2 pts each):
O in O3 _____
C in CH4 _____
Cl in ClO4− _____
K in K2SO4 _____
C in LiCN _____
CHEM 112 – Sample Final Exam
5/17
3) 0.25 mol of PCl5 and 0.15 mol of Cl2 are put in a 3.0 L container. When the system reaches
equilibrium, how many moles of PCl3 are there? Do not use an approximate method. (15
pts)
PCl3(g) + Cl2(g)  PCl5(g)
Kc = 8.18
CHEM 112 – Sample Final Exam
4) For the reaction
Pb(s) + Sn2+(aq)  Pb2+(aq) + Sn(s)
a. Calculate the standard potential. (10 pts)
b. Calculate the equilibrium constant under standard conditions. (5 pts)
c. Calculate the potential, if [Pb2+] = 1.50×10−3 M and [Sn2+] = 2.00 M. (5 pts)
6/17
CHEM 112 – Sample Final Exam
5) What is the pH of a 0.035 M solution of HClO4? (5 pts)
6) What is the pH of a solution that is 0.45 M in HCN and 0.10 M in KCN? (5 pts)
7/17
CHEM 112 – Sample Final Exam
7) What is the pH of a 0.10 M solution of KCN? (15 pts)
8/17
CHEM 112 – Sample Final Exam
9/17
8) 0.153 g of a polymer is dissolved in 100 mL of CH3CN at 30° C. The solution is found to
have an osmotic pressure of 242 Torr. Find the molecular weight of the polymer. (15 pts)
CHEM 112 – Sample Final Exam
10/17
9) A 50.00 mL sample of NaOH solution of unknown concentration is titrated with a 0.1590 M
solution of HBr.
a. What is the pH of the equivalence point? (5 pts)
b. 18.9 mL of HBr is required to reach the equivalence point. How many mmol of NaOH
were in the original sample? (5 pts)
CHEM 112 – Sample Final Exam
11/17
10) A compressed air cylinder has a volume of 15.7 L and is filled to a pressure of 200 atm with
He. The valve is suddenly knocked off, releasing the He to the atmosphere. How much
work is done? Regard the cylinder and the He as the system. (15 pts)
CHEM 112 – Sample Final Exam
11) Balance the following reaction, which occurs in a basic, aqueous solution (15 pts):
PH3(g) + CrO42−(aq)  P4(s) + CrO2−(aq)
12/17
CHEM 112 – Sample Final Exam
12) The equilibrium constant is Keq = 1.43 at 25° C for the reaction
2NO2(g)  N2O4(g)
Find the equilibrium constant at 100° C. (15 pts)
13/17
CHEM 112 – Sample Final Exam
14/17
13) A first-order reaction has a rate constant of k = 6.98 s−1 at 10° C and k = 78.2 s–1 at 90° C.
a. What is the activation energy for this reaction? (10 pts)
b. Estimate the rate constant at 25° C. (5 pts)
CHEM 112 – Sample Final Exam
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14) A 100.0 mL sample of 0.1023 M strychnine (C21H22N2O2) solution is titrated with a 0.2504
M solution of HCl. What is the pH after 15.00 mL of HCl solution has been added? (15 pt)
CHEM 112 – Sample Final Exam
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15) Data for a reaction A  2 B are shown in the graph below.
30
1/[A] (L/mol)
25
20
15
10
5
0
0
20
40
60
Time (s)
a. What is the order of the reaction (5 pts)?
b. What is the rate constant (5 pts)?
80
100
CHEM 112 – Sample Final Exam
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16) What is the solubility of Li2(CO3) [Ksp = 8.2×10−5] in a 0.23 M solution of LiCl? (15 pts)