Organic Chemistry Lab Report #2 PDF

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Chemistry 2612 Organic Chemistry Lab

Lab Report #2

Distillation of Toluene and Cyclohexane

02-13-17

Introduction Distillation is a method used to separate two liquids that are miscible. This separation of liquids can be determined by taking the melting points of these substances. The boiling point of a compound is determined by how strong are the intermolecular forces; the stronger the intermolecular forcer the higher the boiling point. The difference between a fraction distillation and simple distillation is that simple distillation works better for compounds with different boiling points. In this process the liquid is heated and then the compound with lower boiling point starts to evaporate and then condense. Fractional distillation is more efficient for compounds with a difference of boiling point less than 40°C. In addition, fractional distillation gives more pure compounds. The beads in the fractional distillation allow the compound that is being isolated leave behind impurities.

Chemical Properties and Safety Compound

Molecular Weight

Boiling

Melting

Toluene

(g/mol) 92.14

Point (°C) 110

Point (°C) -95.00

Hazards

-

(C6H5CH3)

Irritant of skin, eye, ingestion & inhalation

Cyclohexane

84.16

80

6.47

-

Toxic fumes

-

Irritant of skin, eye,

(C6H12)

ingestion & inhalation -

CNS Depression

-

Flammable Vapor

Experimental Procedure For this distillation, 30ml of a 50:50 mixture of toluene and cyclohexane was obtained. A 100ml round bottom flask was used to pour the 50:50 mixture. Aluminum is placed around the flask like a skirt with stir bar energy high enough in case of needing to remove aluminum. A jack is used to properly position the aluminum under the flask. Before setting up the glassware, a rubbing tubbing was connected to condenser. A rubber band was placed around the upper condenser hookup and lower condenser. Only 2/3 of the Hempel column were filled and grease was used to lubricate male joints. To collect the fractions, a 10ml graduated cylinder was utilized for each one. The condenser tubing was connected properly and the exit tube was set. Once the glassware was assembled a TA checked the set up and the temperature and volume was recorded from the first drop, every 2ml of solution. The hot plate was set 50-60. The thermometer was placed below the side arm for better temperature readings. Fraction 1 and 3 were analyzed b GasLiquid Chromatography. Fraction 2 was not analyzed.

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Data and Observations

Simple Distillation 1st fraction 0 mL 2 mL 4 mL 6 mL 8 mL 10 mL

°C

Simple Distillation 2nd fraction 0 mL 2 mL 4 mL 6 mL 8 mL 10 mL

64 70 79 80 80 81

Fractional Distillation 1st fraction 0 mL 2 mL 4 mL 6 mL 8 mL 10 mL

°C

°C 81 81 81 82 82 83

Fractional Distillation 2nd fraction 0 mL 2 mL 4 mL 6 mL 8 mL 10 mL

65 72 74 76 75 74

Simple Distillation 3rd fraction 0 mL 2 mL 4 mL 6 mL 8 mL 10 mL

°C 80 80 78 84 84 84

°C 84 83 83 83 83 83

Fractional Distillation 3rd fraction 0 mL 2 mL 4 mL 6 mL 8 mL 10 mL

Simple Distillation, Fraction #1 90 80

Boiling Point (C°)

70 60 50 40 30 20 10 0

0

2

4

6

Volume (mL)

8

10

12

°C 100 99 99 99 99 99

Simple Distillation, Fraction #2 83.5

Boiling Point (C°)

83 82.5 82 81.5 81 80.5 80

0

2

4

6

8

10

12

10

12

Volume (mL)

Simple Distillation, Fraction #3 84.2 84

Boiling Point (C°)

83.8 83.6 83.4 83.2 83 82.8 82.6 82.4 0

2

4

6

Volume (mL)

8

Fractional Distillation, Fraction #1 77

Boiling Point (C°)

76 75 74 73 72 71 70

0

2

4

6

8

10

12

Volume (mL)

Fractional Distillation, Fraction #2

Boiling Point (C°)

85 84 83 82 81 80 79 78 77 76 75

0

2

4

6

8

10

12

Volume (mL)

RFE

Fractional Distillation, Fraction #3 100.2 100

Boiling Point (C°)

99.8 99.6 99.4 99.2 99 98.8 98.6 98.4

0

2

4

6

Volume (mL)

8

10

12

Conclusion In the fractional distillation experiment an impure mixture of cyclohexane and toluene was distilled isolating a pure fraction of toluene. Distillation utilizes the differences in boiling points of the two compounds to separate them. The compound that is going to be distilled first is the one with the lower point, in this case it was cyclohexane since its intramolecular forces, London dispersion forces, give it a boiling point of 80°C; this is the first fraction of distillation. Toluene The second fraction was a mixture of the two of the compounds and the third fraction was the toluene since it has a higher boiling point. There were some impurities on the substance since chromatography showed three peaks instead of two. The glass beads in the fractional distillation allow for more surface area for the compound to cool and uncage impurities from the crystal lattice, thus resulting in a purer toluene. Another benefit of using fractional distillation is the cool beads allow the impure substance to undergo a phase change from liquid to gas and as that gas hits the cool beads it returns to the liquid phase and back to the gas phase, but as a purer compound....