Experiment 2 Chm207 Intermediate Organic Chemistry Distillation Technique And To Determine The Boiling Point Of A Liquid 2r5r5

Experiment 2: Distillation technique and to determine the boiling point of a liquid

Objective:  To learn the techniques of distillation and boiling point determination.

Chemicals: 30% of ethanol inwater Boiling chips (5-6 pieces)

Procedure: 1. The round bottom flask was filled with 25ml of 30% ethanol. Few boiling chips was added. 2. A simple distillation apparatus was set up as shown in diagram. The thermometer was put into the the thermometer pocket. 3. The liquid was heated at constant rate during the boiling, which was until the distillation rate was about 2-3 drops per second. 4. A stable temperature was recorded as the boiling point of the liquid to be distilled. 5. The ethanol collected was measured after distillation. 6. The percentage yield of recovery was calculated.

Result & Data: A.

Range of stable temperature (˚C) Start

78

End

84

Boiling point of ethanol :

79 ˚C

B.

Volume (ml)

Initial volume of ethanol in 25ml

30 ×100 =7.5 100

Volume of ethanol collected after distillation

6.9

Calculation of ethanol after distillation

6.9 ×100 =92 7.5

Questions/Discussions: 1. Draw the appratus needed for distillation.

2. Explain why we need to use boiling chips in the distillation process. Boiling chips absorb the heat and temperature will increase. Because of the chips has higher temperature than liquids, then the liquid that s with surface of boiling chips will boils. If a liquid is heated, it may go to temperature above its boiling point, resulting in sudden spurt. To avoid this spurting, boiling chips are added.

3. Ethanol have higher boiling point than propane. Draw the structure of ethanol and propane ann explain why. Ethanol Propane

Ethanol forms bonds between oxygen and hydrogen molecule whereas propane form only hydrogen bonds. Hydrogen bonds are weaker than hydro-oxi bonds thus it takes more heat to break O-H bond than H-H bonds.

4. What is the thereotical value of ethanol’s boiling points? Compare the value with your experimental value of boiling point. Explain why it is differ. The thereotical value is 78˚C while experimental value is 79˚C. During the distillation, at 92% ethanol-water mixture forms azeotrope which hampers further distillation. So ethanol can be made 100% pure.

Conclusion: As a conclusion, the techniques of distillation was learned and the boiling point of ethanol was determined. Only 92% of ethanol was recovered from the distillation process. This may be due to the ethanol vapour is still trap in the apparatus during the boiling process.