2.5.1 - Laboratory Activity : Preparation of Ethanol

Laboratory Activity 2.5.1 : Preparation of Ethanol

Aim: To prepare ethanol in laboratory
Problem statement: How ethanol are prepare in the laboratory?
Hypothesis: Ethanol is prepared through the fermentation of carbohydrates.
Variable:

	»	Fixed variable : Presence of yeast
	»	Manipulated variable : Types of carbohydrate
	»	Responding variable : Formation of ethanol

Material: » Glucose » Sugar cane juice » Cooked rice » Limewater » Distilled water » Yeast

Apparatus: » Conical flask » Delivery tube » Boiling tube » Distillation tube » Liebig condenser » Retort with stand » Thermometer » Bunsen burner

Procedure:

	►	(A) With chlorine 1. 2. 20g of glucose is dissolved with distilled water in a conical flask. 3. 5g of yeast is added into the mixture. 4. A delivery tube is fixed to the conical flask and left for three days. 5. The change on limewater is noted. 6. This video shows the production of alcohol by yeast.
	►	(B) Distillation process 1. 2. After three days, the mixture is filtered and distilled at 78°C by using the apparatus shows in the diagram below. 3. The distillates is examined in terms of color and odor. 4. The experiment can be repeated by using cooked rice, sugar cane juice

Analysis:

	►	The zymase enzyme in yeast breaks down the glucose to carbon dioxide and ethanol. The limewater turn chalky because carbon dioxide was liberated during the fermentation process. ○ $C_6{H}_{12}{O}_6\begin{array}{c}\to \\ \text{yeast}\end{array}{\mathrm{2C}}_2{H}_5\mathit{OH}+{\mathrm{2CO}}_2$
	►	The boiling point of ethanol (78°C) is lower than that of water. Thus, only ethanol will be distilled and condensed.

Conclusion:

►

Ethanol can be prepared through fermentation of any carbohydrate.

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