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Fractional Distillation

This document discusses fractional distillation, which is a technique used to separate mixtures based on differences in boiling points. It involves heating a mixture to vaporize components and passing the vapors up a fractionating column, where they condense separately based on their boiling points. The column provides additional surface area to improve separation when boiling point differences are small (less than 25°C). Fractional distillation is used in oil refining and chemical purification. It separates crude oil into useful fractions like gasoline, diesel, and kerosene. The document provides diagrams of fractional distillation setups and lists materials needed, including chemicals, glassware, packing materials for the column, and a procedure for separating a benzene-toluene

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Mohammad W. Mshir
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218 views3 pages

Fractional Distillation

This document discusses fractional distillation, which is a technique used to separate mixtures based on differences in boiling points. It involves heating a mixture to vaporize components and passing the vapors up a fractionating column, where they condense separately based on their boiling points. The column provides additional surface area to improve separation when boiling point differences are small (less than 25°C). Fractional distillation is used in oil refining and chemical purification. It separates crude oil into useful fractions like gasoline, diesel, and kerosene. The document provides diagrams of fractional distillation setups and lists materials needed, including chemicals, glassware, packing materials for the column, and a procedure for separating a benzene-toluene

Uploaded by

Mohammad W. Mshir
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Soran University/Faculty of Science/Chemistry department General chemistry (P) - 1st Stage

2. Fractional distillation: is the separation of a mixture into its component parts, or


fractions. Chemical compounds are separated by heating them to a temperature at which
one or more fractions of the mixture will vaporize.

Theory of Fractional Distillation:


A simple distillation is incapable of significant purification and separation if the boiling
points of the components are too close. When the difference in boiling points is less than 25
˚C, a modification is necessary, namely insertion of a fractionating column between the
distilling flask and two-way adapter connected with water condenser.

Fractional distillation column (Fractionating column): is a special type of column used


in small scale laboratories as well as large scale industrial processes for the separation of a
mixture of two or more miscible liquids in which the difference in boiling points is less than
25 °C. The apparatus for fractional distillation is similar to that of simple distillation, except
that a fractionating column is fitted in between the distillation flask and the simple
condenser.

Uses of Fractional distillation:


Fractional Distillation is used for both oil refining and purification of reagents and
products. Fractional distillation is used in oil refineries to separate the complex
hydrocarbon mixture into fractions that contain similar boiling points and therefore similar
molecular weights and properties. Petroleum products such as Gasoline, diesel fuel,
kerosene, and jet fuel are some of the different fractions produced by an oil refinery
process.

Figure 1: Fractional distillation apparatus using a Liebig condenser


1 Study year:2019-2020 Lecturer: Akam J.Mustafa
Soran University/Faculty of Science/Chemistry department General chemistry (P) - 1st Stage

Figure 2: How fractional distillation of crude oil works

Materials required:
Chemicals:
• Mixture of (Acetone + Methyl alcohol or Benzene + Toluene)
Laboratory glassware & Apparatus:
• Round-bottom flask (Size: 100 mL)
• Ring stand with clamp
• Fractionating column
• Distilling head (adapter)
• Porcelain chips (as Boiling chips)
• Thermometer adapter
• Water condenser
• Vacuum adapter
• Heating mantle
2 Study year:2019-2020 Lecturer: Akam J.Mustafa
Soran University/Faculty of Science/Chemistry department General chemistry (P) - 1st Stage

Packing column material for fractional distillation


1. Pyrex solid glass beads
2. Glass helices
3. Nichrome wires
4. Steel wools
Note: The rationale for packed fractionating column is to provide a larger surface area for
raising vapors with descending condensates which greatly improves the separation
process. Thus, the more vapor liquid contacts the better the separation.
Efficiency of laboratory fractional distillation depend on the following factors:
1. Length of the column
2. Nature of used compounds
3. Speed of distillation
Procedure:
Take a mixture of Benzene and Toluene (50 mL+50mL) in a distillation flask. To set up the
system follow the given diagram, also you have name of each lab pieces from the material
required section.

3 Study year:2019-2020 Lecturer: Akam J.Mustafa

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