CHEM 244-101: ORGANIC CHEMISTRY II
EXAM STUDY GUIDE AND PRACTICE
EXAM 2024/2025 | ACCURATE REAL EXAM
QUESTIONS WITH VERIFIED ANSWERS |
EXPERT VERIFIED FOR A GUARANTEED
PASS | LATEST UPDATE
,which of the following is an incorrect statement regarding oil out
- it can be caused by insufficient solvent
- the oil mainly consists of impurities which may contaminate the crystals
- it may occur during the cooling period of the crystallization
- the solution needs to be rewards to dissolve the oil - ✔✔ANSW✔✔..the oil mainly
consists of impurities which may contaminate the crystals
which of the steps of the recrystallization can sometimes be skipped -
✔✔ANSW✔✔..hot filtration
name the funnel that is used to collect the crystals while filtering the crystals of a
recrystallized sample - ✔✔ANSW✔✔..buchner funnel
upon addition of charcoal, which color of the solution would indicate the right amount of
decolorizing carbon has been added - ✔✔ANSW✔✔..grey
what technique should be the first method to try for induction of crystallization if the
acetanilide solution does not give crystal upon cooling in the ice bath? -
✔✔ANSW✔✔..scratch the bottom of the container with a glass rod
Which of the following is an incorrect statement concerning the small-scale
recrystallizatoin of naphthalene from ethanol?
- Dissolve impure naphthalene in ethanol by placing the centrifuge tube in a beaker of
hot water.
- Use a large amount of ice cold ethanol to thoroughly wash the crystals.
- Any load in a centrifuge must be balanced with an equivalent load on the opposite side
of the rotor.
- Keep your fingers out of the centrifuge until it comes to a complete stop. -
✔✔ANSW✔✔..Use a large amount of ice cold ethanol to thoroughly wash the crystals.
upon the completion of 1,4-dichlorobenzene, what should be carried out last -
✔✔ANSW✔✔..disconnect the water line
what will cause an observed melting point of a pure compound to be lower than the
correct melting point? - ✔✔ANSW✔✔..heating the sample too fast
What is the minimum amount of time that you should wash your eyes out if they have
been splashed with a hazardous chemical? - ✔✔ANSW✔✔..15 minutes
What waste bottles should be used for disposal of a waste that contains a mixture of
benzoic acid and dichloromethane? - ✔✔ANSW✔✔..halogenated organic waste
When the vapor pressure of a liquid substance equals the atmospheric pressure at a
certain temperature, what will happen? - ✔✔ANSW✔✔..the liquid will begin to boil
, What information concerning the vapor-liquid equilibrium of a binary system cannot be
obtained from a temperature-composition phase diagram? - ✔✔ANSW✔✔..vapor
pressure of a liquid mixture
You wish to distill 45 mL of liquid. What volume capacity of the round bottom flask
should you use? - ✔✔ANSW✔✔..100 mL
In the distillation assembly, a thermometer should be placed at the position -
✔✔ANSW✔✔..where the top of its bulb is slightly below the take-off tube of the still
head
The most important reason for adding boiling chips is - ✔✔ANSW✔✔..to prevent the
liquid from bumping
Ethanol and water cannot be separated by fractional distillation even with a good
fractionating column. This is because - ✔✔ANSW✔✔..ethanol and water form
azeotrope
Which of the following is not a typical characteristic of a high efficiency fractionating
column? - ✔✔ANSW✔✔..low hold up of the liquid
What is most informative for determining the elution order of individual components in a
sample mixture in GC chromatography? - ✔✔ANSW✔✔..boiling point of each
component in the mixture
What will not be suitable for GC analysis? - ✔✔ANSW✔✔..protein molecules
Assuming the fractional distillation in experiment 2C was done perfectly. Which fractions
would most likely show a single methanol peak with percent peak area of 100 on the
GC chromatogram? - ✔✔ANSW✔✔..fractions 1 and 3
Which of the following methods would extract the most caffeine from an aqueous tea
solution?
Extract with three 10 mL portions of dichloromethane.
All the three methods would extract the same amount of caffeine.
Extract with one 30 mL portion of dichloromethane
Extract with two 15 mL portions of dichloromethane. - ✔✔ANSW✔✔..Extract with three
10 mL portions of dichloromethane.
You have collected organic and aqueous layers from an extraction in two separate
beakers without labeling the beakers as aqueous or organic layer. What should you do
to safely and quickly identify the two layers? - ✔✔ANSW✔✔..Add a drop of water to
each beaker
EXAM STUDY GUIDE AND PRACTICE
EXAM 2024/2025 | ACCURATE REAL EXAM
QUESTIONS WITH VERIFIED ANSWERS |
EXPERT VERIFIED FOR A GUARANTEED
PASS | LATEST UPDATE
,which of the following is an incorrect statement regarding oil out
- it can be caused by insufficient solvent
- the oil mainly consists of impurities which may contaminate the crystals
- it may occur during the cooling period of the crystallization
- the solution needs to be rewards to dissolve the oil - ✔✔ANSW✔✔..the oil mainly
consists of impurities which may contaminate the crystals
which of the steps of the recrystallization can sometimes be skipped -
✔✔ANSW✔✔..hot filtration
name the funnel that is used to collect the crystals while filtering the crystals of a
recrystallized sample - ✔✔ANSW✔✔..buchner funnel
upon addition of charcoal, which color of the solution would indicate the right amount of
decolorizing carbon has been added - ✔✔ANSW✔✔..grey
what technique should be the first method to try for induction of crystallization if the
acetanilide solution does not give crystal upon cooling in the ice bath? -
✔✔ANSW✔✔..scratch the bottom of the container with a glass rod
Which of the following is an incorrect statement concerning the small-scale
recrystallizatoin of naphthalene from ethanol?
- Dissolve impure naphthalene in ethanol by placing the centrifuge tube in a beaker of
hot water.
- Use a large amount of ice cold ethanol to thoroughly wash the crystals.
- Any load in a centrifuge must be balanced with an equivalent load on the opposite side
of the rotor.
- Keep your fingers out of the centrifuge until it comes to a complete stop. -
✔✔ANSW✔✔..Use a large amount of ice cold ethanol to thoroughly wash the crystals.
upon the completion of 1,4-dichlorobenzene, what should be carried out last -
✔✔ANSW✔✔..disconnect the water line
what will cause an observed melting point of a pure compound to be lower than the
correct melting point? - ✔✔ANSW✔✔..heating the sample too fast
What is the minimum amount of time that you should wash your eyes out if they have
been splashed with a hazardous chemical? - ✔✔ANSW✔✔..15 minutes
What waste bottles should be used for disposal of a waste that contains a mixture of
benzoic acid and dichloromethane? - ✔✔ANSW✔✔..halogenated organic waste
When the vapor pressure of a liquid substance equals the atmospheric pressure at a
certain temperature, what will happen? - ✔✔ANSW✔✔..the liquid will begin to boil
, What information concerning the vapor-liquid equilibrium of a binary system cannot be
obtained from a temperature-composition phase diagram? - ✔✔ANSW✔✔..vapor
pressure of a liquid mixture
You wish to distill 45 mL of liquid. What volume capacity of the round bottom flask
should you use? - ✔✔ANSW✔✔..100 mL
In the distillation assembly, a thermometer should be placed at the position -
✔✔ANSW✔✔..where the top of its bulb is slightly below the take-off tube of the still
head
The most important reason for adding boiling chips is - ✔✔ANSW✔✔..to prevent the
liquid from bumping
Ethanol and water cannot be separated by fractional distillation even with a good
fractionating column. This is because - ✔✔ANSW✔✔..ethanol and water form
azeotrope
Which of the following is not a typical characteristic of a high efficiency fractionating
column? - ✔✔ANSW✔✔..low hold up of the liquid
What is most informative for determining the elution order of individual components in a
sample mixture in GC chromatography? - ✔✔ANSW✔✔..boiling point of each
component in the mixture
What will not be suitable for GC analysis? - ✔✔ANSW✔✔..protein molecules
Assuming the fractional distillation in experiment 2C was done perfectly. Which fractions
would most likely show a single methanol peak with percent peak area of 100 on the
GC chromatogram? - ✔✔ANSW✔✔..fractions 1 and 3
Which of the following methods would extract the most caffeine from an aqueous tea
solution?
Extract with three 10 mL portions of dichloromethane.
All the three methods would extract the same amount of caffeine.
Extract with one 30 mL portion of dichloromethane
Extract with two 15 mL portions of dichloromethane. - ✔✔ANSW✔✔..Extract with three
10 mL portions of dichloromethane.
You have collected organic and aqueous layers from an extraction in two separate
beakers without labeling the beakers as aqueous or organic layer. What should you do
to safely and quickly identify the two layers? - ✔✔ANSW✔✔..Add a drop of water to
each beaker
