Experiment 1 Simple distillation PDF

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Simple and Fractional Distillation of a Binary Mixture ORGANIC CHEMISTRY LAB I: SECTION 010. CIPION, BENJAMIN TA: LULU WEI

Benjamin Cipion Teaching Assistant: Lulu Wei Experiment 1: Introduction: Public and commercial industry utilize chemical properties of compounds and molecule as a tool for isolation and purification. One fundamental method of isolation is distillation. Over time, technology has advanced, where efficient variations of distillation method have arisen. Some distillation methods include: steam distillation, vacuum distillation, simple distillation, and fractional distillation just to mention a few. Distillation takes advantage of the innate characteristic of molecules as a distinguishing factor for separation. In essence, distillation is the process of vaporizing a liquid mixture to a specified boiling point and converting the vapors back into liquid phase via condensation. The components of a mixture have specified boiling point; these boiling points are used as boundaries for heating. The mixture is heated to said boiling point, vaporized, condensed back to liquid via a condenser and collected. The type of distillation method used, depends on the characteristic of the liquid mixture. For simple distillation, a mixture is heated to a specified boiling point. The vapors are channeled through a distillation head and into a water-cooled condenser where the vapors are cooled to a liquid and collected via a vial. The same approach and setup in simple distillation is performed for Fractional distillation, with the addition of a fractionating column. The fractionating column is a column comprised of aluminum mesh and allows for the vapors to condense and re-vaporize in a cycle with in the column for more effective, efficient component isolation. the boiling point difference between the components within the liquid mixture dictates which distillation method is used. If the boiling point difference is greater than 10 degrees Celsius, Simple distillation is used; if the

boiling point difference is less than 10 degrees Celsius, fractional distillation is selected. It is important to note that the boiling point of the components of the mixture is related to its vapor pressure. A high vapor pressure correlates with a low/lower boiling point, and a low vapor pressure correlates with a high/higher boiling point. Thus, a component with a high vapor pressure, will have a lower boiling point, and in turn will vaporize and collected first. Distillation is the ideal application of Daltons and Raoult’s law, boiling point of a liquid, and vapor pressures. According to Raoult’s law, the vapor pressure immediately over a solvent or mixture is equal to the mole percentage of each component in the mixture. Thus, as heat is added, and the vapor pressure increases, the component with the higher vapor pressure with be vaporized. Dalton’s law postulates that the total pressure exerted by a mixture of non-reacting gases, is equal to the sum of the pressure exert by each component. In totality, as heat is added, vapor pressure increase, and the component with the higher vapor pressure will vaporize first as it exerts more pressure. Furthermore, the intermolecular interactions among the component of the liquid mixture dictates boiling point, as more energy is needed to break such interaction. For experiment 1 simple and fractional distillation methods were conducted on a 1:1 liquid mixture of Cyclohexane and toluene. It is important to note that the 1:1 liquid mixture of cyclohexane and toluene is an azeotrope. An azeotrope is a liquid mixture where its components exhibit constant boiling points and composition in liquid and vapor phases as the distillation process progresses.

Experimental Section: 1:1 Mixture of Liquid Cyclohexane and Toluene

Evaporation of Cyclohexane: Boil liquid mixture @ B.P of Cyclohexane (~81oC)

Evaporation of Toluene: Boil remainder of liquid @ B.P of Toluene (~110oC)

Vaporization: Cyclohexane in Vapor form; Toluene remain in liquid

Vaporization: Toluene in vapor form; (do not boil to dry)

Condensation: Collection of Liquid Cyclohexane in Vial labeled “Fraction 1”

Condensation: Collection of Liquid Toluene in Vial labeled “Fraction 2”

Several aspects should be taken into account when applying distillation techniques. For the experiment procedure, a 1:1 ratio liquid mixture of Cyclohexane and toluene was separated via simple and fractional distillation:

Simple Distillation: Upon mixing a 1:1 ratio of cyclohexane and toluene, totaling 7.0 ml (3.5 ml Cyclohexane and 3.5 ml toluene) in a 10- ml conical vial, boiling stones are then added to the conical vial containing the mixture in order to deliver controlled, uniform heating, and prevent bumping. For simple distillation, the apparatus setup consists of a distillation head with 3 connectors. The bottom connector is connected to the 10-ml conical vial containing the liquid mixture, the middle connector is connected to the condenser and the top connector on the distillation head is used for thermometer placement. The Condenser is water-cooled and consist of 2 irrigation sites. The site furthest from the distillation head is the water inlet site, where was flows in, and the site proximal to the distillation head is the water outlet site, where the water is drained. The water inout setup on the water-cooled condenser is done in this fashion in order to create a temperature gradient across the condenser, where the cooler side is closer to the collection side, and the warmer end closer to the distillation side. Furthermore, an adaptor elbow is place at the end of the condenser (water inlet side) and is the location where the collection vial is attached.

Once the simple distillation apparatus is assembled, the 10-ml conical vial is oriented and placed in a sand bath at the heat source. The heating source is directly attached to an adapter which controls the heating level, with the expected range of 40-70. As the temperature increases

due to heat input, temperature is monitored by the thermometer at the distillation head and maintained at the range of cyclohexane, which is 80 degrees Celsius. Upon reaching and maintaining the boiling point of cyclohexane, the number of liquid drops at specific temperatures are recorded. It is important to note that the vapors rise through the distillation head, into the water-cooled condenser, condensed into a liquid and collected at the vial. Once 3.5-ml of cyclohexane are collected, the heat will be increased and aimed to reached the boiling point of toluene. The temperature and drop collection are recorded, as with cyclohexane. Furthermore, Temperature is maintained at boiling point of toluene; drops are collected until 3.5-ml of toluene is obtained, while making sure liquid mixture is not heated to dry. It is important note that once the 3.5-ml of cyclohexane were collected, the vial is removed, labeled as ‘fraction #1’ and replaced with a second vial labeled ‘fraction #2’ in order to collected the toluene. Also, during heating, the rate of liquid generated from condenser should be monitor as it reflects the rate of heating.

Fractional distillation: The setup and procedure for fractional distillation of a liquid mixture of 1:1 cyclohexane and toluene is identical to that of simple distillation, with the addition of a fractionating column. The fractionating column is place/located between the vial mixture and the down facing distillation head. Thus, the fractionating column is placed at the bottom connector of the distillation head and the distal end of the fractionating column is connected to the vial mixture. The fractionating column is covered by an aluminum sheet to maintain temperature and contained aluminum mesh. The fractionating column allow the vapors to re-condense and revaporizes within the column for efficient distillation of a mixture with a small difference in boiling point.

Table of Chemicals: Name IUPAC name Formula Boiling Point Melting Point Molar Mass Chemical Structure

Cyclohexane Cyclohexane C6H12 80.74oC 6.47oC 84.16 g/mol

cyclohexane

Toluene Methylbenzene C7H8 110.6oC -95.0oC 92.14 g/mol

toluene

Results: (refer to the end of the document for Graphs and Table) Given the total Volume of Cyclohexane and toluene collected for both Simple and fractional distillation, percent recovery can be calculated. Percent recovery is defined as:

% Recovery=

Amount collected(mL) × 100 Amount crude(mL )

Simple Distillation: Cyclohexane: % Recovery=

3.1 mL x 100 3.5 mL

% Recovery=88.5 % Toluene: 3.2 mL ×100 % Recovery= 3.5 mL

% Recovery=91.4 % Fractional Distillation:

Cyclohexane: % Recovery=

3.2 mL ×100 3.5 mL

% Recovery=91.4 % Toluene: % Recovery=

3.1 mL ×100 3.5 mL

% Recovery=88.5 %

Discussion: The percent recovery of cyclohexane and toluene for both Simple and Fractional distillation were over 80%; an indication of effective isolation. The graph for both simple and fraction distillation of cyclohexane and toluene reflect such findings. For the simple distillation of Cyclohexane, the graph reflects that most of the volume collection occurred between a steady temperature increase from 70oC to 80oC. Also, the signature S-shape curved graph is present for the fractional distillation of cyclohexane. For toluene, similar graphical representation is seen. Specifically, the stretch S-curve graph formation is present for the simple distillation of Toluene. Overall, Fractional distillation was more effective for the isolation of cyclohexane, and Simple distillation was more proficient in the isolation of Toluene. For cyclohexane, Fractional distillation may appear to be more effective due to the lower boiling point. Since Fractional distillation is utilized for small boiling point differences, a component with a lower boiling point may be able to better purify due to having the opportunity to re-condense and re-vaporize. Toluene was better isolated with simple distillation, and may be due to having a higher boiling point, where the toluene can be vaporized. Also, some of the vapors or condensation can be lost

in the mesh of the fractional column. However, it is important to note, that the total combine volume for both simple distillation and fractional distillation were identical; 6.3 ml.

Conclusion: Conducting a simple and fractional distillation and retrieving the isolated components, illustrates fundamental properties of an azeotrope liquid mixture. Each component was isolated and separated based on their boiling point, a reflection of the liquid mixture’s vapor pressure; which is described by Dalton’s and Raoult’s law. Simple and fractional distillation techniques, have a wide range of applications; not only in the chemistry laboratory, but in the pharmaceutical, commercial, and industrial realm. Thus, organic chemistry laboratory I accomplished was it set out to do- isolate a 1:1 liquid mixture of cyclohexane and toluene using simple and fractional distillation techniques with a high percentage recovery.

Simple Distillation Cyclohexane Temperature (oC)

Total collected: 6.3 mL Toluene

Fractional Distillation

Total Collected: 6.3 mL Toluene

Total Volume (mL) 0.5

Temperature (0C) 80-85

Total Volu (mL) 0.00

Cyclohexane

Temperature (oC)

60-65

Total Volume (mL) 0.5

80-85

Total Volume Temperature (0C) (mL) 0.00 60-65

65-70

1.5

85-90

0.1

65-70

1.3

85-90

0.00

70-75

1.9

90-95

0.4

70-75

2.2

90-95

0.3

75-80

3.0

95-100

1.0

75-80

3.1

95-100

0.6

80-81

3.1

100-105

2.2

80-81

3.2

100-105

1.6

105-110

3.0

105-110

3.1

110-111

3.2

Total Volume:

3.2 mL

Total Volume:

3.1 mL

Total Volume:

3.1 mL

Total Volume:

3.2 mL

Simple and Fractional Distillation of 1:1 Cyclohexane and Toluene 3.5

3

2.5

2

1.5

1

0.5

0 60-65

65-70

70-75

75-80

80-81

Referecnes:

1. Solomons, T. W. Graham., and Craig B. Fryhle. Organic Chemistry. Wiley, 2011. 2. Weldegirma, S. (2018). Experimental Organic Chemistry (8th ed.). Tampa, FL: PROCOPY. 3. Libretexts. (2020, May 19). Dalton's Law (Law of Partial Pressures). Retrieved May 26, 2020, from https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_ Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Physical_Properties _of_Matter/States_of_Matter/Properties_of_Gases/Gas_Laws/Dalton's_Law_(Law_of_Part ial_Pressures) 4. Cyclohexane. (n.d.). Retrieved May 26, 2020, from https://pubchem.ncbi.nlm.nih.gov/compound/Cyclohexane 5. Toluene. (n.d.). Retrieved May 26, 2020, from https://pubchem.ncbi.nlm.nih.gov/compound/Toluene...