Organic Chemistry I CHM 336 LAB 4 PDF

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Samantha Truckly (2654185) _____/30 Experiment Title: Simple and Fractional Distillation of a Cyclohexane and Toluene Mixture Date (of performed experiments): February 20th, 2018 Laboratory Partners: Selina and Mackenzie Goals: To successfully distill a solution by extracting one chemical from another through a heating process using a distillation apparatus. Procedure: 1. Pipet 10mL of cyclohexane and toluene into a 50mL flask with a spin bar. 2. Assemble the apparatus for simple distillation and position the bulb of the thermometer below the neck of the distilling head. 3. Turn on water to condenser and variac to heat the solution until vapors reach the thermometer bulb. 4. Increase rate of heating. 5. Discard first few drops of distillate (may contain water or volatile impurities). 6. Collect distillate in the receiver at the rate of 1-2 drops per second. 7. Record temperature vs. volume of distillate during entire distillation. Take readings every 1-2mL or more frequently if temperature is changing rapidly. 8. Stop distillation when 1-2mL remains in pot and remove from heat source to let apparatus cool to room temperature. 9. Disassemble the apparatus and place all organic liquids in proper container. Wash and dry all glassware. 10. Correct boiling points to standard pressure. 11. Estimate and record temperature ranges at which fractions were collected and estimate the volumes of distillate collected at each temperature. 12. Graph the corrected boiling point vs. volume (mL) of distillate. Observations:  We started our hot plate at 315C.  Our beaker was covered in aluminum foil. Results: Boiling point of Toluene – 110.6C Refractive Index of Toluene – 1.4969 Boiling Point of Cyclohexane – 80.74C Refractive Index of Cyclohexance - 1.4465 Trial 1 (%): -1984.1(1.5023)+2970=0% Cyclohexance (assumably mostly water) Trial 2 (%): -1984.1(1.4503)+2970=92.45% Cyclohexane (7.55% Toluene) Trial 3 (%): -1984.1(1.4773)+2970=38.89% Cyclohexane (61.11% Toluene)

Fraction #

ST (Celsius)

ET (Celsius)

# of Drops

mRI

CRI

Samantha Truckly (2654185) 1 2 3

65 70 80

Cyclohexane % 1.4465 1.4969

RI Toluene 100 0

70 80 84

20 20 20

1.5 1.448 1.475

1.5023 1.4503 1.477

Discussion: Simple distillation is used when two chemicals have a fifty-degree or more difference in their boiling point, purifying the solution by vaporizing the chemical with the lowest boiling point first and fractional distillation is used when two chemicals have a forty-degree or less difference in their boiling points. The vapor pressure of a substance is the pressure of the gas that's given off when it evaporates and the volatility of a substance is a general term that we use to describe how easily something vaporizes. Then, the boiling point decreases as the vapor pressure increases. Based on cyclohexane’s lower boiling point, it is expected to distill before toluene. After collecting the data for fractional distillation, we can see a relationship of the concentration of cyclohexane and its refractory index. Conclusion: In this lab, we were able to successfully distill a solution by extracting one chemical from another through a heating process using a distillation apparatus. Before this lab, I did not have much knowledge on how to set up or work the apparatus and I was also not familiar with finding the refractory index. For future experiments like this one, it is important to remember to calculate a boiling point range rather than a set point and then take that average for your calculated boiling point. References: Schoffstall, A.; Gaddis B.; Drueling, M.; Melting Point; Microscale and Miniscale Organic Chemistry Laboratory Experiments, McGraw-Hill, (2011), 52-72. Mohrig, J.R.; Alberg, D.G.; Hofmeister, G.E.; Schatz, P.F.; Hammond, C.N.; Laboratory Techniques in Organic Chemistry; Freeman, New York, 2014, 77, 174-194, 203-205. Discretionary:...