Experiment #: 4
Title: Biosynthesis – Synthesis and Characterization of Ethanol from Sucrose
Purpose:
Is to explore the principles of organic synthesis by fermenting sucrose to produce ethanol.
Procedure:
A. Preparation of Yeast Slurry:
a. Weigh approximately 3.5 g of dry baker’s yeast and transfer it into a clean beaker.
b. Add 50 mL of distilled water to the beaker.
c. Use a glass stirring rod to stir and gently macerate the yeast to break the cells
and release enzymes.
i. Add 0.35 g of sodium phosphate to the yeast slurry.
d. Stir to mix thoroughly.
B. Preparation of Sugar Solution:
a. Weigh 51.5 g of table sugar (sucrose) and place it in a separate beaker.
b. Add 150 mL of distilled water and stir until the sugar dissolves completely.
C. Fermentation Setup:
a. Pour most of the sugar solution into a fermentation flask, reserving a
small amount.
b. Transfer the yeast slurry into the fermentation flask.
c. Rinse remaining yeast into the flask using the reserved sugar solution.
i. Insert a rubber stopper securely into the flask to seal it.
d. Attach a gas trap containing lime water to the side arm of the flask to allow
CO₂ to escape while preventing oxygen and contaminants from entering.
e. Allow the mixture to ferment undisturbed for approximately one week or
until CO₂ bubble production ceases.
D. Filtration of Fermented Solution:
a. Add 10 g of diatomaceous earth (Celite) to the flask to aid in filtration.
b. Set up a vacuum filtration apparatus with a Büchner funnel, filter paper, and
a filter flask.
c. Wet the filter paper w/ distilled water and start the aspirator vacuum.
d. Pour the fermented mixture into the funnel and collect the filtrate (ethanol-
water solution).
E. Fractional Distillation:
a. Transfer the filtrate to a distillation setup.
b. Perform fractional distillation to isolate 100 mL of ethanol-rich distillate.
c. Collect and label the distillate for analysis.
F. Density Measurement:
a. Measure the density of the distillate using a hydrometer.
i. Record the reading.
b. Separately, weigh 100 mL of the distillate using a graduated cylinder
and analytical balance.
c. Calculate density using the formula:
i. Density = Mass/Volume
G. Ethanol Confirmation Tests
Title: Biosynthesis – Synthesis and Characterization of Ethanol from Sucrose
Purpose:
Is to explore the principles of organic synthesis by fermenting sucrose to produce ethanol.
Procedure:
A. Preparation of Yeast Slurry:
a. Weigh approximately 3.5 g of dry baker’s yeast and transfer it into a clean beaker.
b. Add 50 mL of distilled water to the beaker.
c. Use a glass stirring rod to stir and gently macerate the yeast to break the cells
and release enzymes.
i. Add 0.35 g of sodium phosphate to the yeast slurry.
d. Stir to mix thoroughly.
B. Preparation of Sugar Solution:
a. Weigh 51.5 g of table sugar (sucrose) and place it in a separate beaker.
b. Add 150 mL of distilled water and stir until the sugar dissolves completely.
C. Fermentation Setup:
a. Pour most of the sugar solution into a fermentation flask, reserving a
small amount.
b. Transfer the yeast slurry into the fermentation flask.
c. Rinse remaining yeast into the flask using the reserved sugar solution.
i. Insert a rubber stopper securely into the flask to seal it.
d. Attach a gas trap containing lime water to the side arm of the flask to allow
CO₂ to escape while preventing oxygen and contaminants from entering.
e. Allow the mixture to ferment undisturbed for approximately one week or
until CO₂ bubble production ceases.
D. Filtration of Fermented Solution:
a. Add 10 g of diatomaceous earth (Celite) to the flask to aid in filtration.
b. Set up a vacuum filtration apparatus with a Büchner funnel, filter paper, and
a filter flask.
c. Wet the filter paper w/ distilled water and start the aspirator vacuum.
d. Pour the fermented mixture into the funnel and collect the filtrate (ethanol-
water solution).
E. Fractional Distillation:
a. Transfer the filtrate to a distillation setup.
b. Perform fractional distillation to isolate 100 mL of ethanol-rich distillate.
c. Collect and label the distillate for analysis.
F. Density Measurement:
a. Measure the density of the distillate using a hydrometer.
i. Record the reading.
b. Separately, weigh 100 mL of the distillate using a graduated cylinder
and analytical balance.
c. Calculate density using the formula:
i. Density = Mass/Volume
G. Ethanol Confirmation Tests
