Organic+-+Fractional+Distillation

__Basics of Fractional Distillation__
Fractional Distillation is the process of separating a mixture into different parts or fractions. Chemical compunds are ussually broken up into different fractions by heating the mixture to its boiling point and at which at that time will evaporate off into its different parts or fractions. This process can be used to purify solvents, chemicals, natural products or other other materials and is done by using a special distillation apparatus which uses a Leibig condenser, fractioning column, a thermometer, and anti-bumping granules (also known as boiling chips). (Picture obatained from** [|**http://www.chemistrydaily.com/chemistry/Fractional_distillation**]**) __Leibig condenser__ -** a glass tube which helps keep things at a cool temperature by having cold running water go through it __Fractioning Column__ **- An apparatus used for seperation of fluids (gaseous or liquid) components by vapor-liquid fractionation or liquid-liquid extraction or liquid-solid absorption.(source for definition of Fractioning Column [])** __Anti-bumping granules__ - Small stones used to make liquids boil more smoothly, they are communly used in distillation.**
 * The Distillation Apparatus

__Experiment Example of Fractional Distillation__
One example of an experiment done using fraction distillation is making an __ester,__ they are used for making artifficial flavors aswell as other compounds.

__Experiment__
As an example, consider the distillation of a mixture of ethanol and water. Ethanol boils at 78.5°C whilst water boils at 100°C. So by gently heating the mixture, the ethanol will boil off first. Some mixtures form azeotropes*, where the mixture boils at a lower temperature than either component. In the ethanol example, a mixture of 95% ethanol and 5% water boils at 78.2°C, so the ethanol cannot be completely purified by distillation. The apparatus is assembled as in the diagram. The mixture is put into the round bottomed flask along with a few anti bumping granules, and the fractionating column is fitted into the top. As the mixture boils, vapor rises up the column. The vapor condenses on the glass platforms inside the column, and runs back down into the liquid below,refluxing distillate. Only the most volatile of the vapors stays in gaseous form all the way to the top. The vapor at the top of the column will be almost pure ethanol. This then passes into the condenser, which cools it down until it liquefies. The process continues until all the ethanol boils out of the mixture. This point can be recognized by the sharp rise in temperature shown on the thermometer, from the boiling point of ethanol to the boiling point of water. (Experiment was obtained from []
 * azeotrope a mixture of one or two chemicals in such a ratio that its compistion cannot be changed.

__Video of a fractinal distillation experiment__**

media type="custom" key="4255411" video obtained from []

__Fractional Distillation of Crude Oils__
This system works on the basis of difference in boiling points of chains of hydrocarbons. The boiling points increase as you add more carbon atoms to a chain. This is because the boiling point of any substance depends on the strength of the intramolecular forces. The more atoms you put into a substance, the more forces are created between the particles and more energy is required to break the intramolecular forces. This effectively increases the boiling point of the substance. For example,
 * Methane (CH4) boils at -161°C
 * Ethane (C2H6) boils at -89°C
 * Pentane (C5H12) boils at 36°C
 * Octane (C8H18) boils at 125°C

Petroleum refining:
This is the process by which the different component fractions present in crude oil are separated. The crude oil is heated to boiling point, and then passed through a large distillation column called a //distillation// or //fractionation// tower. The tower is divided into many separate sections, and each of these are heated to different temperatures. The coolest sections are near the top and the hottest at the bottom. When the gaseous crude oil passes through a section, any fraction present in it that has a boiling point lower than the temperature of the section it is in will cool and form a liquid that can be drawn off. Any fraction that has a boiling point higher than the temperature of the section it is in will remain in the gaseous state and carry on to the next section of the tower. This continues until the last of the fractions, very small and therefore still in the gaseous state, are collected at the top of the tower.

[|Picture source]