This document defines and describes several chemical separation processes: filtration, sublimation, crystallization, and distillation. It provides brief definitions of each process. Filtration separates solids from liquids by passing the liquid through a filter medium. Sublimation is the direct transition from solid to gas phases without passing through the liquid phase. Crystallization involves the formation of solid crystals from a solution or melt. Distillation separates mixtures based on differences in boiling points, with the more volatile components distilling off first. Examples of each process are also given.

1. Chemistry
Created by
Haris Iftikhar
9-O(junior)
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2. Contents
Filtration(definition)
Sublimation(definition)
Crystallization (definition)
Distillation(definition)
Processes
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3. Filtration
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 Filtration is commonly the mechanical or
physical operation which is used for the
separation of solids from fluids (liquids or
gases) by interposing a medium through which
only the fluid can pass.
 The fluid that passes through is called the
filtrate.
 Filtration is also used to describe some
biological processes, especially in water
treatment and sewage treatment in which
undesirable constituents are removed by
absorption into a biological film grown on

4. Sublimation
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 Sublimation is the transition of a substance
directly from the solid to the gas phase without
passing through the intermediate liquid phase.
 Sublimation is an endothermic reaction that
occurs at temperatures and pressures below a
substance's triple point.
 The reverse process of sublimation is
desublimation or deposition, in which a
substance passes directly from a gas to a solid
phase.

5. Crystallization
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 Crystallization is the (natural or artificial)
process of formation of solid crystals
precipitating from a solution, melt or more
rarely deposited directly from a gas.
 Crystallization is also a chemical solid–
liquid separation technique, in which mass
transfer of a solute from the liquid solution
to a pure solid crystalline phase occurs. In
chemical engineering crystallization occurs
in a crystallizer. Crystallization is therefore
an aspect of precipitation, obtained
through a variation of the solubility
conditions of the solute in the solvent, as
compared to precipitation due to chemical
reaction.

6. Distillation
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 In distillation, the more volatile component
of the mixture—that is, the part that is more
easily vaporized—is separated from the less
volatile portion.
 Distillation is widely used in industries that
refine oil, desalinate water, create liquor,
beer and wine, and produce many chemical
products used in homes and factories.

7. Processes
 Filtration: The process of filtration involves the flow of water through a
granular bed, of sand or another suitable media, at a low speed. The media
retains most solid matter while permitting the water to pass. The process of
filtration is usually repeated to ensure adequate removal of unwanted particles
in the water. This type of slow filtration over a granular bed is generally known as
slow sand filtration.
 Sublimation: An example of sublimation is seen when iodine, on being
heated, changes from a dark solid to a purplish vapor that condenses directly to
a crystalline solid upon striking a cool surface. In this way pure crystals of iodine
are prepared. Some other substances, e.g., mercuric chloride, can be prepared
by sublimation. Solid carbon dioxide, commonly known as dry ice, sublimes at -
78.5°C ( - 109.3°F). Sublimation also occurs when air saturated with water vapor
is suddenly cooled below the freezing point of water.
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8. Processes (Continued)
 Crystallization: A definite amount of given substance is dissolved in a specific
amount of water in a beaker to prepare aqueous solution of substance. The beaker is
heated to dissolve maximum amount of solute. The solution must be saturated. In
second step, solution is filtered while hot. The insoluble impurities are separated. The
filtered solution is cooled to produce crystals of substance. Crystals so obtained are
wet. They are dried by solar heat or by placing between the paper folds to remove
moisture.
 Distillation: A simple distillation apparatus consists of three parts ;flask equipped
with a thermometer and with an outlet tube from which vapours exit;a condensor
consisting of two tubes at different places and a vessel in which the condensed vapor
is collected. The mixture of substances is placed in the flask and heated. Ideally,
the substance with the lowest boiling point vaporizes first , the temperature
remaining constant until that substance has completely distilled. The vapor is led
into the condenser where, on being cooled, it reverts to the liquid (condenses)
and runs off into a receiving vessel. The product so obtained is known as the
distillate. Those substances having a higher boiling point remain in the flask and
constitute the residue
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