Lab Report
Organic Chemistry II Lab 9
Fermentation of a Carbohydrate: Ethanol from Sucrose * Introduction
Ethanol is one of the oldest alcohols and also the least toxic one. Industrially, ethanol is made most economically by hydration of ethylene. However, ethanol that is intended for human consumption must, by law, be prepared by fermentation. By either method, ethanol, of course, has the same formula, structure, and properties. The fermentation takes place with the assistance of enzymes from yeast in 2 steps: first sucrose (a disaccharide whose structure is in your textbook) is broken down to two monosaccharides, glucose and fructose. These monosaccharides are then converted into ethanol and carbon dioxide. * Materials
250-mL Erlenmeyer flask
250-mL Beaker
Bruchner funnel
Fermentation apparatus
Distillation apparatus
Vacuum filtration assembly
Water
Sucrose
Potassium phosphate
Celite
Disodium hydrogen phosphate
Dried baker’s yeast *
* Procedure
Part I
Place 20.0 g of sucrose into a 250-mL Erlenmeyer flask, add 100 mL of water, and shake until sucrose is completely dissolved.
To the solution add 0.50 g of disodium hydrogen phosphate, 1 g of potassium phosphate, and 2 g of dried baker’s yeast. Mix the contents thoroughly by shaking the mixture.
Set up the apparatus for the fermentation, label it, and leave it under 30-35 degrees Celsius for 5-7 days.
Part II
Remove the rubber stopper from the flask without disturbing the solution.
Prepare a vacuum filtration assembly. Into a 250-mL beaker, place 100 mL of water and one table spoon of Celite. Stir and pour mixture into the Bruchner funnel while the water is running and a vacuum is applied. Discard the water collected.
Carefully decant the liquid in the fermentation flask above the sediment through the Celite filter aid.
Obtain a distillation setup, assemble it, and place the solution.
Heat up the liquid gradually until it starts to boil. When the temperature reaches 78
Fermentation of a Carbohydrate: Ethanol from Sucrose * Introduction
Ethanol is one of the oldest alcohols and also the least toxic one. Industrially, ethanol is made most economically by hydration of ethylene. However, ethanol that is intended for human consumption must, by law, be prepared by fermentation. By either method, ethanol, of course, has the same formula, structure, and properties. The fermentation takes place with the assistance of enzymes from yeast in 2 steps: first sucrose (a disaccharide whose structure is in your textbook) is broken down to two monosaccharides, glucose and fructose. These monosaccharides are then converted into ethanol and carbon dioxide. * Materials
250-mL Erlenmeyer flask
250-mL Beaker
Bruchner funnel
Fermentation apparatus
Distillation apparatus
Vacuum filtration assembly
Water
Sucrose
Potassium phosphate
Celite
Disodium hydrogen phosphate
Dried baker’s yeast *
* Procedure
Part I
Place 20.0 g of sucrose into a 250-mL Erlenmeyer flask, add 100 mL of water, and shake until sucrose is completely dissolved.
To the solution add 0.50 g of disodium hydrogen phosphate, 1 g of potassium phosphate, and 2 g of dried baker’s yeast. Mix the contents thoroughly by shaking the mixture.
Set up the apparatus for the fermentation, label it, and leave it under 30-35 degrees Celsius for 5-7 days.
Part II
Remove the rubber stopper from the flask without disturbing the solution.
Prepare a vacuum filtration assembly. Into a 250-mL beaker, place 100 mL of water and one table spoon of Celite. Stir and pour mixture into the Bruchner funnel while the water is running and a vacuum is applied. Discard the water collected.
Carefully decant the liquid in the fermentation flask above the sediment through the Celite filter aid.
Obtain a distillation setup, assemble it, and place the solution.
Heat up the liquid gradually until it starts to boil. When the temperature reaches 78