ORGANIC CHEMISTRY LAB 2: Separation of Organic Liquid Mixtures
Introduction: In this experiment, a mixture of two compounds, cyclohexane and toluene, was separated into fractions by the techniques of simple and fractional distillation. The individual fractions that were gathered from the distillation were analyzed using gas chromatography (GC) and used to compare the efficiencies of the two different distillation techniques. The ultimate goal of this experiment was to determine whether simple or fractional distillation was the more efficient means of separating volatile compounds.
Key Experimental Details, Observations, and Results:
Key Experimental Details and Observations:
Simple and Fractional Distillation set up:
To set up distillation apparatus:
For simple distillation: Connect a distilling flask to the bottom of the side-arm joint.
For fractional distillation: Connect a distilling flask to the bottom of the fractionating column, wrapped in aluminum foil. Connect the top of the fractionating column to the bottom of the side-arm flask. 2.
Insert the thermometer into the top of the side-arm joint through the rubber stopper. The bottom tip of the thermometer should rest within the side-arm joint in a position slightly lower than the bottom of the condenser. 3.
Attach the side of side-arm joint to the end of the condenser. 4.
Attach the remaining end of the condenser to the vacuum adaptor. 5.
Connect the receiving flask to the bottom of the vacuum adaptor. 6.
Connect water hose from sink faucet to condenser water intake nozzle. Connect a second water hose from condenser exhaust nozzle to sink for drainage. 7.
Stabilize the entire apparatus with clamps.
To prepare gas chromatography injections:
Dilute fractions by combining 10µL of fraction sample with 990µL of dichloromethane (DCM). 2.
Prepare syringe by filling syringe entirely with DCM and discharging it into waste container. Do this ten times. Afterwards fill the syringe with the diluted fraction sample and discharge into waste container five times. 3.
Draw 1µL of air into syringe, followed by 1µL of the fraction sample, then followed by 1-2 µL more of air. The 1µL of sample should be suspended between the air pockets. 4.
Insert syringe into injection port and discharge quickly and smoothly. Remove syringe promptly. 5.
Repeat for remaining fractions once gas chromatography for previous sample has completed. GC Instrument Number:
Simple distillation fractions for this lab were analyzed using gas chromatography machine #2. Fractional distillation fractions for this lab were analyzed using gas chromatography machine #2.
Literature boiling point and temperature recordings:
Cyclohexane (C6H12) boiling point: 80.7°C
Toluene (C7H8) boiling point: 111.0°C Table of Volumes:
Rt peak 1
Rt peak 2
% area peak 1
% area peak 2
Fraction 1 – Simple
Fraction 2 – Simple
Fraction 3 – Simple
Fraction 1 – Fractional
Fraction 2 – Fractional
Fraction 3 – Fractional
Cyclohexane Standard GC #1
Toluene Standard GC #1
Cyclohexane Standard GC #2
Toluene Standard GC #2
Discussion and Conclusion:
The compounds used in...
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