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DISTILLATION

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Distillation• Simple laboratory distillation• Industrial distillation• Fermentation and distillation

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Distillation

How would you separate the yellow liquid from the green mixture?

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Distillation

• Yellow bp = 100oC• Blue bp = 80oC• Green bp = 100oC• How do we get to Blue liquid out of

the Green mixture?

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Distillation• Distillation can separate one liquid from another

in a mixture solution• Distillation works by evaporating one of the

liquids from the solution• It is then cooled and condensed into a separate

container• The other liquid is left behind

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Distillation

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Distillation• Distillation is used to purify a compound by

separating it from a non-volatile or less-volatile material

• When different compounds in a mixture have different boiling points they can be separated into individual components by distillation

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DistillationWhere is distillation used?

• Distillation is used to separate crude oil into specific fractions, such as petrol or kerosene

• Water is distilled to remove impurities (e.g. salt from seawater)

• Air is distilled to separate it into O2 and N2

• Distillation of fermented solutions has been used since ancient times to produce beverages with a high alcohol content

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Distillation• Distillation is a method of separating mixtures based on differences in their boiling points• Distillation is a physical separation process and not a chemical reaction

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DistillationSimple Laboratory distillation

apparatus

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DistillationSimple laboratory distillation

apparatus

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Distillation• Boiling points are measured by recording the temperature

(within a specific range) on a thermometer while performing a distillation

• The distillation method of boiling point determination measures the temperature of the vapours above the liquid

• These vapours are in equilibrium with the boiling liquid and are the same temperature as the boiling liquid

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Distillation• The boiling point: temperature at which the

vapour pressure of the liquid phase of a solution equals the external (atmospheric) pressure acting on the surface of the liquid

• The vapour pressure: is an indication of a liquid's evaporation rate. It relates to the tendency of particles to escape from the liquid

• A substance with a high vapour pressure at normal temperatures is referred to as volatile

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Distillation• The vapour pressure of the liquid will increase as

the temperature of the liquid increases

• These vapours are in equilibrium with the boiling liquid and are the same temperature as the boiling liquid

• When the vapour pressure equals the atmospheric pressure the liquid will boil

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Distillation• Different compounds boil at different

temperatures because each has a different, characteristic, vapour pressure

• Compounds with higher vapour pressures will boil at lower temperatures (i.e. first to distil)

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DistillationIndustrial Distillation

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Distillation

Large scale industrial distillation applications are required for:• petroleum refineries• petrochemical and chemical plants• natural gas processing plants

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Distillation• Industrial distillation is performed in large,

vertical, cylindrical columns known as distillation towers or distillation columns

• Diameters: 65 cm ~16 m• Heights: 6 m ~ 90 m or more

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Distillation

http://www.schoolscience.co.uk/content/4/chemistry/fossils/p7.html

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Distillation• Industrial towers use reflux to separate products

• Reflux: down flowing liquid provides cooling and condensation of the up flowing vapours

• Fractions collected at specific parts of the tower

• The more reflux that is provided the better the tower's separation of lower boiling materials from higher boiling materials

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http://www.schoolscience.co.uk/content/4/chemistry/fossils/p7.html

Fraction: a group of compounds with boiling points & carbon chains within a given range

Distillation• Fractionating columns use trays to help separate

the mixture by allowing the mixed vapors to cool, condense, and vaporize again

• With each condensation-vaporization cycle the vapors are enriched in a certain component

• A larger surface area allows more cycles, improving separation.

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Distillation• When the process feed has a diverse composition (e.g. crude oil)

outlets at intervals up the column allow for the withdrawal of different fractions collected on trays having different carbon chain lengths and boiling ranges

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DistillationThe lightest products(lowest boiling point)exit from the top of the column

The heaviest products(highest boiling point)

exit from the bottom of the column

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DistillationFermentation and distillation

Distillation• Ethanol fermentation is a biological process in which

sugars such as glucose, fructose, or sucrose are converted into cellular energy

• The metabolic waste produce are ethanol and carbon dioxide

• Yeasts perform this conversion in the absence of oxygen: ethanol fermentation is anaerobic

• Ethanol fermentation occurs in the production of alcoholic drinks, biofuel, and bread

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Distillation

• A distilled beverage, liquor, or spirit is an alcoholic beverage containing ethanol (CH3CH2OH)

• Produced by distilling (i.e. concentrating by distillation) ethanol produced by means of fermenting grain, fruit, or vegetables

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Distillation• A still is a apparatus used to distill miscible

or immiscible liquid mixtures by heating to selectively boil and then cooling to condense the vapor

• Stills are used to produce beverages containing ethanol (CH3CH2OH)

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DistillationFermentation and distillation

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DistillationConclusion

• Distillation is a process of physically separating mixtures

• Difference in vapour pressure and boiling point

• Used in the laboratory, industry, and in the fermentation process

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Questions1. What are the similarities and differences

between the 3 methods of distillation?

2. Why is temperature range related to purity?

3. Would a mixture distil quicker or slower in a vacuum?

4. Design an experiment to separate 3 liquids from a mixture