Version C.
1. A material which is a carcinogen causes:
A) irritation to eyes and excess tearing
B) inheritable genetic abnormalities
C) visible destruction of human tissue
D) cancer
2. What is the name of the following piece of glassware.
A) Hirsch Funnel
B) Buchner Funnel
C) Separatory Funnel
D) Transfer Funnel
3. How should excess methylene chloride (m.p. -96.7oC, b.p. 40o C ) be disposed of?
A) into the solid non-halogenated organic waste container
B) into the solid halogenated organic waste container
C) into the liquid non-halogenated organic waste container
D) into the liquid halogenated organic waste container
4. Which of the following techniques is not used for chemical identification purposes?
A)
B)
C)
D)
melting point
extraction of acidic substances
IR spectroscopy
thin layer chromatography
5. Compound A has a melting point of 100-101°C and compound B has a melting point
of 80-81°C. What would be a reasonable expected beginning for the melting point
range of a 1 to 1 by mass mixture of these two compounds?
A) 90°C
B) 100°C
C) 110°C
D) 75°C
Version C Page 1 of 14, 2230L Fall 2011
6. Given the enlarged section of a thermometer, what is the correct temperature to
record in oC?
A) 93
B) 93.0
C) 93.00
D) 93.000
7. The melting point of a sample contaminated with a small amount of an insoluble
impurity, such as sand, would be expected to be ...
A) the same as pure sand
B) the same as the pure sample
C) higher than the pure sample
D) lower than the pure sample
8. A chemist found that the melting point range of Unknown X was 182-185°C. The
literature suggested that X must be one of four compounds. Those were:
Compound A, literature melting point range 184-185°C
Compound B, literature melting point range 184-187°C
Compound C, literature melting point range 182-183°C
Compound D, literature melting point range 181-184°C
The chemist made mixtures of X with each of the four compounds. The melting point
ranges of these mixtures were: X with A, 184-185°C; X with B, 178-185°C; X with C,
170-181°C; X with D, 176-184°C. What is Unknown X?
A)
B)
C)
D)
Compound A
Compound B
Compound C
Compound D
9. What would be the end result of recrystallization in which NOT ENOUGH
recrystallization solvent was used?
A) No effect
B) The obtained product would have low levels of impurities.
C) A lower than expected recovery would result
D) The obtained product would have high levels of impurities
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10. If you were going to carry out a recrystallization of benzoic acid and the following
solvents were available, which would be your best choice of solvent to use for this
recrystallization? This table lists the solubility of benzoic acid per 100 grams of solvent
at 20oC and 80oC and the boiling point of the solvent.
Solvent
grams Benzoic
grams Benzoic Acid/100 Boiling Point of
Acid/100 g
g solvent at 80o C
Solvent, oC
solvent at 20 o C
A
0.50
98.2
302
B
0.50
95.3
127
C
28.4
95.3
95
D
0.50
15.8
115
A) Solvent A
B) Solvent B
C) Solvent C
D) Solvent D
11. A student has 1.00 g. of a crude product that exhibits a melting point of 121.5122.0°C. After recrystalization 0.50 g of purified product are recovered with a melting
point of 121.5-121.9°C. Which is the best interpretation of these results?
A) The original product was pure, and some of it remained in the solvent when
crystallizing.
B) The original product was impure, and the impurity weighed 0.5g.
C) More solvent needs to be removed from the purified product.
D) The original material was impure and the recovered material still contains impurities.
12. If you are purifying a 1.00 g sample which is contaminated by 20 wt % of an
impurity, what is the maximum amount in grams of a pure sample you could recover?
A). 1.20 g
B) 0.20 g
C) 0.80 g
D) 1.00 g
13. What is the reading from the refractometer shown?
A) 1.33046
B) 1.336
C) 1.346
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D) 1.3346
14. The refractive index of water is taken. The display is on the left. On the same
instrument, an unknown sample Z is measured. From the display shown, what is the
corrected refractive index of Unknown Z? The literature value of the refractive index of
water is 1.3330.
A) 1.4262
B) 1.4255
C) 1.4276
D) 1.4269
15. A mixture of Ethylacetate (EA) and Butyl acetate (BA) was analyzed on a
refractometer. A corrected refractive index of 1.3804 was obtained. The refractive index
of pure ethyl acetate is 1.3723 and of pure butyl acetate is 1.3941. What is the
composition of the mixture?
A) 59.9 % EA & 40.1 % BA
C) 62.8 % EA & 37.2 % BA
B) 40.1 % EA & 59.9 % BA
D) 37.2 % EA & 62.8 % BA
16. The following reaction was performed:
2-methyl-2-hexanol + HCl
→
2-chloro-2-methylhexane + H2O
4.25 mL of 2-methyl-2-hexanol (density 0.812 g/mL, Mol. Wt. 116 g/mol) was mixed
with 14.8 mL of 12M hydrochloric acid to form 2-chloro-2-methylhexane (Mol. Wt.
134.5 g/mol). If 3.58 grams of 2-chloro-2-methylhexane were isolated, then what
was the percent yield?
A.
B.
C.
D.
3.58 %
81.8 %
89.5 %
84.2 %
17. You measure out material on the balance. The balance display reads 1.2000 g.
Which of the following describes what you should do with this number.
A) Record 1.2000 g in your notebook. Later neatly write this on datasheet.
B) Record 1.2 g in your notebook. Later neatly write this on datasheet.
C) Record 1.2000 g on your datasheet. Later neatly write this in your notebook.
D) Record 1.2 g on your datasheet. Later neatly write this in your notebook.
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18. Which of these compounds gives the spectrum shown?
A) Cyclohexane
B) Cyclohexanol
C) Cyclohexanone
D) Cyclohexanecarboxylic acid
19. If you were trying to distinguish between an ester and a ketone what region in the
IR would you examine?
A) Region I, 3100-3600 cm-1
B) Region III, 2100-2400 cm-1
C) Region IV, 1680-1800 cm-1
D) Region V, 1050-1200 cm-1
20. Which of these statements describes the relationship between frequencies in the IR.
A) 3100 cm-1 is higher energy than 1100cm-1
B) 3100 cm-1 is lower energy than 1100cm-1
C) 3100 cm-1 is higher amplitude than 1100cm-1
D) 3100 cm-1 is lower amplitude than 1100cm-1
21. Which of the following pairs cannot be easily distinguished by IR spectroscopy?
A) heptane and heptanol
B) heptanoic acid and heptanone
C) heptane and octane
D) heptane and heptanoic acid
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22. Below is a GC trace which was made on a system with the following conditions.
Flow = 60mL/min
Inj.=Det= 120oC
Column = 80oC= Carbowax 5 %, 4” x 1/8”
Chart Speed = 2.0 cm/min
Injection volume = 2 l
What is the retention time of peak B?
A. 2.5 minutes
B. 5.5 minutes
C. 22.0 minutes
23. What is the area of the peak below?
A. 3.7 cm2
B. 108 cm2
C. 22.7 cm2 D. 7.4 cm2
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D. 10.0 minutes
24. A mixture of following compounds was injected to a gas chromatograph (Carbowax
5 %, 4” x 1/8”Column)
Compound
Boiling Point °C
Mol. Wt. g/mol
Refractive Index
(nD)
Methylcyclohexane
101
112
1.422
Pentane
36
72
1.358
Octane
126
114
1.398
2,3-dimethyloctane
165
142
1.367
heptane
98
100
1.387
Which compound has the longest retention time?
A. pentane B. methylcyclohexane
C. 2,3-dimethyloctane
D. octane
25. If the temperature of the column is raised by 15oC, what will happen to the retention
time of the compounds?
A. retention time will increase
B. retention time will decrease
C. retention time will not change
D. the change in retention time can not be predicted.
26. Given the chart of number of drops verses temperature below, what is the boiling
point of the second compound to distill?
125
120
Temperature (C)
115
110
105
100
95
90
85
80
75
0
5
10
15
20
25
30
Drops
A) 87o C
B) 105o C
C) 115o C
D) 116o C
27. The process whereby liquids continuously boil in a lower portion of a distillation
apparatus, the vapors rise then condense and drop back down, is called what?
A) a theoretical plate
B) a eutectic mixture
C) an azeotrope
D) reflux
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28. How many tetrahedral stereocenters are in the compound shown?
A) 6
B) 4
C) 3
D) 2
29. A solution was made by mixing 0.673 g of an unknown material in 25.00 ml of water
and test the rotation in a 20.0 cm tube. This material rotates light by + 7.87o. What is
the specific rotation of this material?( []= / (c * l ) .
A) + 146 o
B) + 14.6 o
C) + 1.46 o
D) + 0.146 o
30. A mixture of (R)-2-butanol and (S)-2 butanol has an optical rotation of +4.87o. The
specific rotation of pure (R)-2- Butanol is +13.50. What are the percentages of the (R)
and (S) isomers in this sample?
A) 36.1% (R),
B) 63.9% (R),
C) 68.0% (R) ,
D) 32.0% (R),
63.9% (S)
36.1% (S)
32.0% (S)
68.0% (S)
31. You take 0.498 g of a sugar and dissolve it in 25.00 ml of water and take a
polarimetry reading using the 2.0 dm tube. Your observed rotation is + 3.25o. Given
these literature values for specific rotations, what is your compound?
Name
]
D-Glucose
+98
D- Galactose
+ 82
D-Allose
+15
Sucrose
+64.5
Maltose
+178
A. D-Allose
B. D-Galactose
C. Sucrose
D. Maltose
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32. Calculate the Rf of the spot on the TLC plate shown.
A) 0.30
B) 0.38
C) 0.50
D) 3.0
33. Given the following TLC plate, list compounds A, B & C in order of decreasing
polarity: (The highest polarity in each is in bold)
A). B > A > C
C). A > C > B
B). C > A > B
D). B > C > A
34. In this TLC plate an authentic sample of caffeine is on the left and reaction product
S is on the right. Which of the following conclusions is best supported by this TLC
plate?
s olvent front
origin
A)
B)
C)
D)
S is pure caffeine
S is impure caffeine
S is a pure compound but not caffeine
S is an impure compound that is not caffeine
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35. Which compound from the TLC/Column experiment had the largest Rf value and
why?
A) Ferrocene because it was more polar.
B) Ferrocene because it was less polar
C) Acetylferrocene because it was more polar
D) Acetylferrocene because it was less polar
36. A TLC plate has been run and the following Rf values have been found for
compounds A, B, C, and D.
Compound
Rf
A
0.45
B
0.29
C
0.065
D
0.81
Predict the order (first to last) of elution from an alumina column. (to elute means to exit
or dissociate)
A) C, B, A, D
B) B, C, D, A
C) A, D, C, B
D) D, A, B, C
37. What is the main use of column chromatography?
A) to depolarize liquid mixtures
B) to identify unknown compounds in a mixture
C) to determine the polarity of compounds
D) to purify solids
38. In the separation of acidic substances experiment, what was expected to be
present in the organic layer after extractions with NaHCO3?
A) 2-naphthol only
B) benzoic acid only
C) both of the above
D) neither of the above
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39. 2-naphthol (pKa 9.1) and cyclopentadiene (pKa 16) are dissolved in MTBE. The
following four bases are available. Which one would be best to get the 2-naphthol to
enter the aqueous phase as napthanoate anion and leave the cyclopentadiene in the
organic layer?
The bases are listed with the pKa values of their conjugate acids. (Hint: The lower the
pKa, the stronger the acid. The stronger the acid the weaker the conjugate base.)
A) HC≡CNa
B) NH2-C6H4-ONa
C) NO2-C6H4-ONa
D) NaF
25
10.3
7.2
3.1
40. What is the structure of benzoic acid?
41. During the acidic separation a student began with 40.0 mL of MTBE solution
containing 1.00 g each of benzoic acid and 2-naphthol. If 1.1378 g of the brown 2naphthol and 0.345 g of benzoic acid was recovered, what was the percent recovery of
the 2-naphthol? (remember to use correct significant figures.)
A) 1.14 %
B) 30.3%
C) 114%
D) 113.78%
42. Which molecule is caffeine?
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43. During the caffeine lab, if a large excess of drying agent (Na2SO4) was used to dry
the organic liquid, select the statement which best explains this impact on the calculated
% recovery and the purity as assessed by melting point.
A) The calculated percent
B) The calculated percent
C) The calculated percent
D) The calculated percent
recovery increased, the purity remained unchanged.
recovery increased, the purity decreased.
recovery decreased, the purity remained unchanged.
recovery decreased, the purity decreased.
44. Certain actions during the extraction of caffeine procedure contribute to an artificial
increase in the percent recovery of caffeine. Select the actions that contribute to this
effect.
I. The strings and the bag are weighed along with the tea.
II. Water condenses on the watch glass during the final isolation step.
III. Caffeine maintains a partial solubility in water and the liquid-liquid extraction is not
optimal.
A) I only
B) I and II only
C) II only
D) I, II and III
45. The solid recovered from the tea extraction was analyzed using TLC. What factor
was used to determine the purity of the recovered material?
A) Rf
B) Molecular weight
C) Number of spots
D) Distance solvent traveled
46. A student goes to the balance. The balance reads 1.529 g. The balance is zeroed.
Two tea bags are added. The balance reads 7.418 g. The tea bags are removed
and extracted. The balance is zeroed. A clean watch glass is placed on the
balance. It reads 22.502 g. The extracted liquid is poured onto the watch glass
and allowed to evaporate. The same watch glass is placed back on the balance.
The balance reads 22.769 g. What was the percent recovery of caffeine?
A) 32.6 %
B) 3.59 %
C) 2.98 %
D) 0.0359%
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47. During the Qualitative Analysis 1 experiment, an IR, an index of refraction (R.I) and
a boiling point range of an unknown material was obtained. If the boiling point range
was 60-72oC, the index of refraction was 1.3810, and the IR looked like the following,
then choose the correct identity of the material.
Name
Boiling point (oC)
Refractive index
A
Acetone
56
1.3588
B
2-butanone
70
1.3787
C
heptane
77
1.3820
D
2,3-butadione
78
1.3950
48. What physical property made the organic layer in the SN1 reaction float to the
surface of the hydrochloric acid-water mixture and not sink to the bottom?
A) Refractive Index
B) Solubility
C) Density
D) Molecular Weight
49. The transformation of 2-methyl-2-butanol into 2-chloro-2-methylbutane occurred
readily in the presence of HCl. If instead of HCl, NaCl was used, the reaction would not
have occurred. Why?
A) The H+ is needed to convert –OH, into a much better leaving group.
B) The Na+ binds strongly with the Cl- and prevent the nucleophile from attacking.
C) The Cl- from the NaCl is different than the Cl- from the HCl and one is a better
nucleophile.
D) The polarity of the HCl encourages the substitution to take place.
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50. During the course of this class, 7 different types of separations and/or purifications
were performed (recrystallization, acid-base extraction, TLC, column chromatography,
liquid-liquid extractions, vacuum filtration, and distillation).
If you carried out a reaction and you wound up with 8.87 g of a roughly 50/50 mixture
composed of Acetone (pKa 19, melting point of -198 oC, bp= 57 oC) and Toluene (pka
= 40, melting point -90oC, bp=110 oC). Which of these available procedures would be
best to separate these two materials from each other?
A) Vacuum filtration
B) Distillation
C) Liquid liquid extraction
D) Column chromatography
Good luck on the rest of your finals and have a safe and enjoyable Christmas Break.
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