CHEM 233 Lesson 4 Quiz American Public University |
Questions with Answers & Rationales | 2026 Update
SECTION 1: DISTILLATION & PURIFICATION TECHNIQUES
(Questions 1-20)
Question 1
What type of distillation will you perform first in the elimination reaction experiment?
A) Simple distillation
B) Fractional distillation
C) Steam distillation
D) Vacuum distillation
Correct Answer: B
Rationale: A fractional distillation is performed first. This involves the use of a
fractionating column to provide multiple condensation/evaporation cycles over a given
distance, allowing separation of compounds with close boiling points .
Question 2
A fractional distillation is less efficient (less capable of giving pure product) than a
simple distillation.
A) True
B) False
Correct Answer: B
Rationale: This statement is false. Fractional distillation is more efficient than simple
distillation because the fractionating column provides multiple theoretical plates for
separation, allowing better separation of components with close boiling points .
,Question 3
The distillate collected from the final simple distillation should have a head temperature
of 80°C to 85°C. What does this temperature correspond to?
A) The boiling point of the starting alcohol
B) Roughly the boiling point of the desired alkene product
C) The boiling point of water
D) The decomposition temperature of the product
Correct Answer: B
Rationale: The head temperature of 80-85°C corresponds to roughly the boiling point
of the desired alkene product. This is the fraction collected as the final product after the
initial fractional distillation separates it from the starting material .
Question 4
Which of the following accurately describes fractional distillation?
A) Involves a single condensation/evaporation cycle
B) Uses a fractionating column for multiple condensation/evaporation cycles
C) Can only separate immiscible liquids
D) Is less efficient than simple distillation
Correct Answer: B
Rationale: Fractional distillation involves the use of a fractionating column to provide
multiple condensation/evaporation cycles over a given distance. This allows for better
separation of components with close boiling points .
Question 5
,A mixture of 0.9 mole fraction B is distilled by fractional distillation using a Vigreux
column having two theoretical plates. What is the composition of the distillate
collected?
A) 0.10 mole fraction B
B) 0.30 mole fraction B
C) 0.50 mole fraction B
D) 0.70 mole fraction B
Correct Answer: B
Rationale: Based on phase diagram analysis, fractional distillation with two theoretical
plates (plus the initial boiling plate) yields distillate with approximately 0.30 mole
fraction B. The initial boiling of the mixture in the distillation flask before the column
adds an additional "plate" .
Question 6
The below phase diagram corresponds to what type of mixture?
A) Ideal solution
B) Non-ideal solution with positive deviation
C) Non-ideal solution with negative deviation
D) Azeotropic mixture
Correct Answer: C
Rationale: The phase diagram showing a minimum boiling point corresponds to a non-
ideal solution with a negative deviation from Raoult's law. In such mixtures, the
interactions between different components are stronger than in the pure liquids .
Question 7
If a liquid mixture containing 60 mole percent B was distilled using a simple distillation,
at what temperature would the liquid mixture boil?
A) 50°C
B) 68°C
, C) 80°C
D) 100°C
Correct Answer: B
Rationale: Based on the phase diagram, a mixture containing 60 mole percent B boils at
approximately 68°C during simple distillation. This is the temperature at the initial
boiling point of the mixture .
Question 8
If a liquid mixture containing 60 mole percent B was distilled using an efficient fractional
distillation column, what temperature would be read on the thermometer at the top of
the fractionating column?
A) 50°C
B) 60°C
C) 68°C
D) 80°C
Correct Answer: A
Rationale: With an efficient fractional distillation column (sufficient theoretical plates),
the temperature at the top of the column would be approximately 50°C, corresponding
to the boiling point of the more volatile component being collected as distillate .
Question 9
If a liquid mixture containing 80 mole percent B were distilled using an efficient
fractional distillation column, what would be the composition of the liquid remaining in
the distillation pot?
A) 20 mole percent B
B) 50 mole percent B
C) 75 mole percent B
D) 90 mole percent B
Questions with Answers & Rationales | 2026 Update
SECTION 1: DISTILLATION & PURIFICATION TECHNIQUES
(Questions 1-20)
Question 1
What type of distillation will you perform first in the elimination reaction experiment?
A) Simple distillation
B) Fractional distillation
C) Steam distillation
D) Vacuum distillation
Correct Answer: B
Rationale: A fractional distillation is performed first. This involves the use of a
fractionating column to provide multiple condensation/evaporation cycles over a given
distance, allowing separation of compounds with close boiling points .
Question 2
A fractional distillation is less efficient (less capable of giving pure product) than a
simple distillation.
A) True
B) False
Correct Answer: B
Rationale: This statement is false. Fractional distillation is more efficient than simple
distillation because the fractionating column provides multiple theoretical plates for
separation, allowing better separation of components with close boiling points .
,Question 3
The distillate collected from the final simple distillation should have a head temperature
of 80°C to 85°C. What does this temperature correspond to?
A) The boiling point of the starting alcohol
B) Roughly the boiling point of the desired alkene product
C) The boiling point of water
D) The decomposition temperature of the product
Correct Answer: B
Rationale: The head temperature of 80-85°C corresponds to roughly the boiling point
of the desired alkene product. This is the fraction collected as the final product after the
initial fractional distillation separates it from the starting material .
Question 4
Which of the following accurately describes fractional distillation?
A) Involves a single condensation/evaporation cycle
B) Uses a fractionating column for multiple condensation/evaporation cycles
C) Can only separate immiscible liquids
D) Is less efficient than simple distillation
Correct Answer: B
Rationale: Fractional distillation involves the use of a fractionating column to provide
multiple condensation/evaporation cycles over a given distance. This allows for better
separation of components with close boiling points .
Question 5
,A mixture of 0.9 mole fraction B is distilled by fractional distillation using a Vigreux
column having two theoretical plates. What is the composition of the distillate
collected?
A) 0.10 mole fraction B
B) 0.30 mole fraction B
C) 0.50 mole fraction B
D) 0.70 mole fraction B
Correct Answer: B
Rationale: Based on phase diagram analysis, fractional distillation with two theoretical
plates (plus the initial boiling plate) yields distillate with approximately 0.30 mole
fraction B. The initial boiling of the mixture in the distillation flask before the column
adds an additional "plate" .
Question 6
The below phase diagram corresponds to what type of mixture?
A) Ideal solution
B) Non-ideal solution with positive deviation
C) Non-ideal solution with negative deviation
D) Azeotropic mixture
Correct Answer: C
Rationale: The phase diagram showing a minimum boiling point corresponds to a non-
ideal solution with a negative deviation from Raoult's law. In such mixtures, the
interactions between different components are stronger than in the pure liquids .
Question 7
If a liquid mixture containing 60 mole percent B was distilled using a simple distillation,
at what temperature would the liquid mixture boil?
A) 50°C
B) 68°C
, C) 80°C
D) 100°C
Correct Answer: B
Rationale: Based on the phase diagram, a mixture containing 60 mole percent B boils at
approximately 68°C during simple distillation. This is the temperature at the initial
boiling point of the mixture .
Question 8
If a liquid mixture containing 60 mole percent B was distilled using an efficient fractional
distillation column, what temperature would be read on the thermometer at the top of
the fractionating column?
A) 50°C
B) 60°C
C) 68°C
D) 80°C
Correct Answer: A
Rationale: With an efficient fractional distillation column (sufficient theoretical plates),
the temperature at the top of the column would be approximately 50°C, corresponding
to the boiling point of the more volatile component being collected as distillate .
Question 9
If a liquid mixture containing 80 mole percent B were distilled using an efficient
fractional distillation column, what would be the composition of the liquid remaining in
the distillation pot?
A) 20 mole percent B
B) 50 mole percent B
C) 75 mole percent B
D) 90 mole percent B
