CHM 2211L Test Questions with Correct Answers Already Passed Latest Update 2025
What is a technique used to purify organic solids? - Answers recrystallization
When an organic chemist conducts a recrystallization, he chooses a solvent that will what? - Answers
completely dissolve both the desired compound and any other organic impurities when that solvent is at
BP
In addition to solubility at boiling temperature requirement of the solvent in recrystallization, the
desired compound must also be what? - Answers insoluble in the chosen solvent at cold temperatures,
and the organic impurities must remain soluble when solution is cooled.
Insoluble impurities are typically removed by what in recrystallization? - Answers hot gravity filtration
What do the seed crystals do? - Answers they serve as nucleation sites where more molecules of the
desired compound deposit themselves in layers
what is the purpose of the icebath during recrystallization? - Answers it maximizes crystal formation
in recrystallization, by what method are the crystals collected? - Answers vacuum filtration
What is the purpose of a hot gravity filtration? - Answers so it doesn't crystallize and to remove
impurities rather than to isolate solids
Why is it good to use the stemless funnel for hot gravity filtration? - Answers it prevents what is being
filtered from cooling and forming crystals too early
What is a ligroin? - Answers a non-polar solvent. colorless and flammable liquid.
Why is HCl used instead of plain deionized water in p-phenetidine is dissolved in HCl? - Answers because
it forms a salt by protonating the ammonia group, making it easy to dissolve
What is the purpose of the sodium acetate solution in the amide synthesis of acetophenetidin? -
Answers we need a base to take away an H so that acetic anhydride can complete the reaction. So it
buffers rxn mix
What is the phenomena that occurs when a liquid is heated above its BP in a clean, smooth container. -
Answers superheating
Why should you always use a boiling stone or a boiling stick whenever you heat any liquid in the lab? -
Answers to avoid bumping
How is the melting point of a pure substance defines as? - Answers the temp at which the solid phase is
in equilibrium with the liquid phase.
In an IR, what can be found between 1550-1900? - Answers C=O C=N C=C
In an IR, what can be found in 2000-2300? - Answers c (triple bond) cc (triple bond) n
, around 3000, what can be found in IR? - Answers N-HO-H C=CH C (Triple bond) CH
Why is CO2 used as a solvent in solid liquid extractions? - Answers it offers a greener alternative, readily
available, nonflammable, nontoxic and safe for enviornment. Ease of removal of solvent at end of
procedure (converts into a gas and boils away) "carbon neutral"
How does extraction work in brewing a cup of coffee? - Answers the hot water extracts organic
compounds from ground coffee beans
What are the criteria for a liquid-liquid extraction to be successful? - Answers the 2 solvents chosen for
extraction must be immiscible-the compounds to be extracted must have different affinities for the two
solvents
what is a strong enough base to deprotonate a carboxylic acid? - Answers hydroxide ion
what is not reactive with basse, so it remains unchanged in the organic phace? - Answers a neutral
organic molecule
What do we use to wash an organic layer to remove the majority of dissolved water? - Answers brine
What absorbs the water that is dissolved in the organic solvent? - Answers anhydrous salt
what is the drying agent removed by in extraction? - Answers decanting or by gravity filtration
is hexane and water miscible? - Answers no, hexane would be top layer
is methylene chloride and water miscible? - Answers no water will be top layer
is ethanol and water miscible? - Answers yes
is ether and water miscible? - Answers no, ether would be top layer
Explain why phenol is much more acidic than cyclohexanol. - Answers conjugate base of cyclohexanol is
stronger cus the neg charge on the O atom is delocalized, so phenol is a stronger acid than cyclohexanol
What is the difference between extracting and washing? - Answers extraction is selectively removing a
compound of interest from a mixture using a solvent. Washing is removing unwanted compounds from
a mixture using a solvent.
What is it called when tiny droplets of one liquid become suspended in the other? - Answers emulsion
Essential oils are often isolated from their plant sources using a technique called what? - Answers steam
distillation
Why is it important to soak the cloves in water for several min prior to beginning the distillation? -
Answers it will allow water to penetrate the cloves and should allow more eugenol to be isolated
What is a technique used to purify organic solids? - Answers recrystallization
When an organic chemist conducts a recrystallization, he chooses a solvent that will what? - Answers
completely dissolve both the desired compound and any other organic impurities when that solvent is at
BP
In addition to solubility at boiling temperature requirement of the solvent in recrystallization, the
desired compound must also be what? - Answers insoluble in the chosen solvent at cold temperatures,
and the organic impurities must remain soluble when solution is cooled.
Insoluble impurities are typically removed by what in recrystallization? - Answers hot gravity filtration
What do the seed crystals do? - Answers they serve as nucleation sites where more molecules of the
desired compound deposit themselves in layers
what is the purpose of the icebath during recrystallization? - Answers it maximizes crystal formation
in recrystallization, by what method are the crystals collected? - Answers vacuum filtration
What is the purpose of a hot gravity filtration? - Answers so it doesn't crystallize and to remove
impurities rather than to isolate solids
Why is it good to use the stemless funnel for hot gravity filtration? - Answers it prevents what is being
filtered from cooling and forming crystals too early
What is a ligroin? - Answers a non-polar solvent. colorless and flammable liquid.
Why is HCl used instead of plain deionized water in p-phenetidine is dissolved in HCl? - Answers because
it forms a salt by protonating the ammonia group, making it easy to dissolve
What is the purpose of the sodium acetate solution in the amide synthesis of acetophenetidin? -
Answers we need a base to take away an H so that acetic anhydride can complete the reaction. So it
buffers rxn mix
What is the phenomena that occurs when a liquid is heated above its BP in a clean, smooth container. -
Answers superheating
Why should you always use a boiling stone or a boiling stick whenever you heat any liquid in the lab? -
Answers to avoid bumping
How is the melting point of a pure substance defines as? - Answers the temp at which the solid phase is
in equilibrium with the liquid phase.
In an IR, what can be found between 1550-1900? - Answers C=O C=N C=C
In an IR, what can be found in 2000-2300? - Answers c (triple bond) cc (triple bond) n
, around 3000, what can be found in IR? - Answers N-HO-H C=CH C (Triple bond) CH
Why is CO2 used as a solvent in solid liquid extractions? - Answers it offers a greener alternative, readily
available, nonflammable, nontoxic and safe for enviornment. Ease of removal of solvent at end of
procedure (converts into a gas and boils away) "carbon neutral"
How does extraction work in brewing a cup of coffee? - Answers the hot water extracts organic
compounds from ground coffee beans
What are the criteria for a liquid-liquid extraction to be successful? - Answers the 2 solvents chosen for
extraction must be immiscible-the compounds to be extracted must have different affinities for the two
solvents
what is a strong enough base to deprotonate a carboxylic acid? - Answers hydroxide ion
what is not reactive with basse, so it remains unchanged in the organic phace? - Answers a neutral
organic molecule
What do we use to wash an organic layer to remove the majority of dissolved water? - Answers brine
What absorbs the water that is dissolved in the organic solvent? - Answers anhydrous salt
what is the drying agent removed by in extraction? - Answers decanting or by gravity filtration
is hexane and water miscible? - Answers no, hexane would be top layer
is methylene chloride and water miscible? - Answers no water will be top layer
is ethanol and water miscible? - Answers yes
is ether and water miscible? - Answers no, ether would be top layer
Explain why phenol is much more acidic than cyclohexanol. - Answers conjugate base of cyclohexanol is
stronger cus the neg charge on the O atom is delocalized, so phenol is a stronger acid than cyclohexanol
What is the difference between extracting and washing? - Answers extraction is selectively removing a
compound of interest from a mixture using a solvent. Washing is removing unwanted compounds from
a mixture using a solvent.
What is it called when tiny droplets of one liquid become suspended in the other? - Answers emulsion
Essential oils are often isolated from their plant sources using a technique called what? - Answers steam
distillation
Why is it important to soak the cloves in water for several min prior to beginning the distillation? -
Answers it will allow water to penetrate the cloves and should allow more eugenol to be isolated
