CHEM 238 STUDY GUIDE 2025/2026 QUESTIONS AND
SOLUTIONS MARKED A+
✔✔The glassware was not properly dried prior to the reaction. - ✔✔Less ester is
produced.
✔✔The lid was left off the anhydrous alcohol bottle. - ✔✔Less ester is produced.
✔✔An excess of methanol was used. - ✔✔More ester is produced.
✔✔A drying agent was added to the reaction flask. - ✔✔More ester is produced.
✔✔Procedural steps required to convert benzoic acid into methyl benzoate via a
Fischer esterification. - ✔✔Dissolve the benzoic acid in methanol in a round bottom
flask.
Add conc. sulfuric acid and heat under reflux on a steam bath.
Pour the reaction mix into ice, and rinse the reaction flask with dichloromethane. Collect
the combined layers in a test tube.
Wash the dichloromethane layer with sodium carbonate solution, followed by a wash
with sodium chloride solution.
Dry the dichloromethane by distillation on a steam bath.
Distill the remaining liquid ester in a vial on a heating mantle.
✔✔The reaction solvent is methanol, which bumps violently when heated. - ✔✔Boiling
chips were added to the round bottom flask prior to the reaction being heated under
reflux.
✔✔The unreacted carboxylic acid was neutralized under mild conditions. - ✔✔The
reaction mix was washed with sodium carbonate solution.
✔✔Heating under reflux keeps the reaction temperature high without evaporation. -
✔✔The flask was fitted with a condenser and heated for twenty minutes.
✔✔The Fischer esterification is catalyzed by acid, but water will push the equilibrium
back to the reactant side. - ✔✔Concentrated sulfuric acid was added to the flask
containing carboxylic acid and alcohol.
✔✔It was observed that the magnesium sulfate swirled around freely at the bottom of
the flask. What does this observation indicate? - ✔✔The correct amount of drying agent
has been used.
✔✔The safety hazard warning for acetyl chloride labels it as a lachrymator. Which of the
following statements best defines what a lachrymator is? - ✔✔Exposure to the chemical
vapors make you cry.
, ✔✔Benzoic acid is a lachrymator. - ✔✔False
✔✔Methanol is flammable. - ✔✔True
✔✔Ammonia is corrosive. - ✔✔True
✔✔10% sodium carbonate solution must be used in the fume hood. - ✔✔False
✔✔Dichloromethane is flammable. - ✔✔False
✔✔Which of the following is the best choice of acid catalyst in an acid-catalyzed
esterification reaction? - ✔✔A few drops of concentrated sulfuric acid.
✔✔Starting with equimolar quantities of acetic acid and alcohol, which of these alcohols
will give the highest yield of ester? - ✔✔1-propanol
✔✔What trend is evident from the data sets? - ✔✔The yield of ester increases as the
branching in the alcohol decreases.
✔✔In Fischer esterification, what was in the organic layer? - ✔✔Ester
Layer was on top
✔✔In Fischer esterification, what was in the aqueous layer? - ✔✔Sulfuric acid
Carboxylic acid
Alcohol
Layer was on bottom
✔✔Procedural steps required to generate a low molecular mass ester and to
characterize it by smell. - ✔✔Add 10 drops of liquid carboxylic acid to a clean dry test
tube.
Smell the acid by wafting your hand over the open tube.
Add 10 drops of alcohol to the carboxylic acid.
Add 5 drops of concentrated sulfuric acid to the mixture.
Shake the tube then place it in a warm water bath for 20 minutes.
Allow to cool, and pipet out the organic layer onto a watch glass.
Allow any excess alcohol time to evaporate, then smell the ester by wafting your hand
over the watch glass.
✔✔What might happen if a low molecular weight carboxylic acid is exposed to a slightly
acidic aqueous environment such as one's skin? - ✔✔It will produce burns.
SOLUTIONS MARKED A+
✔✔The glassware was not properly dried prior to the reaction. - ✔✔Less ester is
produced.
✔✔The lid was left off the anhydrous alcohol bottle. - ✔✔Less ester is produced.
✔✔An excess of methanol was used. - ✔✔More ester is produced.
✔✔A drying agent was added to the reaction flask. - ✔✔More ester is produced.
✔✔Procedural steps required to convert benzoic acid into methyl benzoate via a
Fischer esterification. - ✔✔Dissolve the benzoic acid in methanol in a round bottom
flask.
Add conc. sulfuric acid and heat under reflux on a steam bath.
Pour the reaction mix into ice, and rinse the reaction flask with dichloromethane. Collect
the combined layers in a test tube.
Wash the dichloromethane layer with sodium carbonate solution, followed by a wash
with sodium chloride solution.
Dry the dichloromethane by distillation on a steam bath.
Distill the remaining liquid ester in a vial on a heating mantle.
✔✔The reaction solvent is methanol, which bumps violently when heated. - ✔✔Boiling
chips were added to the round bottom flask prior to the reaction being heated under
reflux.
✔✔The unreacted carboxylic acid was neutralized under mild conditions. - ✔✔The
reaction mix was washed with sodium carbonate solution.
✔✔Heating under reflux keeps the reaction temperature high without evaporation. -
✔✔The flask was fitted with a condenser and heated for twenty minutes.
✔✔The Fischer esterification is catalyzed by acid, but water will push the equilibrium
back to the reactant side. - ✔✔Concentrated sulfuric acid was added to the flask
containing carboxylic acid and alcohol.
✔✔It was observed that the magnesium sulfate swirled around freely at the bottom of
the flask. What does this observation indicate? - ✔✔The correct amount of drying agent
has been used.
✔✔The safety hazard warning for acetyl chloride labels it as a lachrymator. Which of the
following statements best defines what a lachrymator is? - ✔✔Exposure to the chemical
vapors make you cry.
, ✔✔Benzoic acid is a lachrymator. - ✔✔False
✔✔Methanol is flammable. - ✔✔True
✔✔Ammonia is corrosive. - ✔✔True
✔✔10% sodium carbonate solution must be used in the fume hood. - ✔✔False
✔✔Dichloromethane is flammable. - ✔✔False
✔✔Which of the following is the best choice of acid catalyst in an acid-catalyzed
esterification reaction? - ✔✔A few drops of concentrated sulfuric acid.
✔✔Starting with equimolar quantities of acetic acid and alcohol, which of these alcohols
will give the highest yield of ester? - ✔✔1-propanol
✔✔What trend is evident from the data sets? - ✔✔The yield of ester increases as the
branching in the alcohol decreases.
✔✔In Fischer esterification, what was in the organic layer? - ✔✔Ester
Layer was on top
✔✔In Fischer esterification, what was in the aqueous layer? - ✔✔Sulfuric acid
Carboxylic acid
Alcohol
Layer was on bottom
✔✔Procedural steps required to generate a low molecular mass ester and to
characterize it by smell. - ✔✔Add 10 drops of liquid carboxylic acid to a clean dry test
tube.
Smell the acid by wafting your hand over the open tube.
Add 10 drops of alcohol to the carboxylic acid.
Add 5 drops of concentrated sulfuric acid to the mixture.
Shake the tube then place it in a warm water bath for 20 minutes.
Allow to cool, and pipet out the organic layer onto a watch glass.
Allow any excess alcohol time to evaporate, then smell the ester by wafting your hand
over the watch glass.
✔✔What might happen if a low molecular weight carboxylic acid is exposed to a slightly
acidic aqueous environment such as one's skin? - ✔✔It will produce burns.
