#12 - Preparation of Ethanol by Fermentation Introduction:
When grains, tubers, and fruits ferment, the carbohydrates in them are converted by a series of reactions to ethanol, CH3CH2OH. Various enzymes contained in yeast speed up the reaction involved. Prior to this experiment, your teacher mixed some yeast with sugar and warm water. This mixture was added to a large bottle containing 2500 mL of warm water and 500 mL of molasses. This has been quietly fermenting for several days.
In this experiment, you will distill the ethanol from the fermentation mixture, and then you will determine some of the properties of the purified ethanol.
Purpose: To prepare ethanol and identify some if its components.
Apparatus: Use the diagram below to help set up your equipment.
Materials: Molasses and yeast mixture, wooden splints, boiling chips
Calculations: Prepare two temperature versus time graphs. One for the first distillation, one for the second distillation. Compare the two graphs. Are there any differences?
2. What are the temperatures at the beginning and end of each distillation?
3. What is the odour of the second distillate?
4. Does this portion ignite when tested with a burning splint?
5. What is the chemical equation for the preparation of ethanol from sucrose , C12H22O11?
6. What is the chemical equation for the combustion of ethanol?
7. What are some of the most important industrial
uses for ethanol?