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Separating Substances (Chromatography (Paper Chromatography (Pure…
Separating Substances
Chromatography
Paper Chromatography
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Impure Substance
A Impure substance will show up as more than one dot on a chromatogram and have a range of melting point and boiling point
Chromatogram
A chromatogram is produced by inserting the paper into a solvent with the ink placed on the origin line and positioned above the solvent line
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RF Value
The RF value is distance travelled by a given component divided by the distance travelled by the solvent front
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With your ruler, measure the distance the solvent traveled, and measure the distance the test solution traveled. Calculate the retention factor by simply divide the distance the solution traveled by the distance the solvent traveled.
Colourless Substance
Colourless Substances can be exposed to locating agents to make them couloured to then it can be separated using chromatography
Methods of purification
Distillation
Distillation is used for separating mixtures based on differences in the condition required to change the phase of components of the mixture
Simple Distillation
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Example
When a solution of salt in water is heated, the water boils and escapes as steam, leaving the salt behind as a solid
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Fractional Distillation
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Example
This method uses a tall column where there is a range of temperatues in it - the higher on the bottom and the lower on the top.
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When it reaches a certain height, the temp. falls velow its boiling point so it condenses back into the distillation flask
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Crystallisation
process by which a solid forms where atoms or are highly organized into a structure known as a crystal
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process of separating suspended solid matter from a liquid, by causing the latter to pass through the pores of some substance, called a filter this liquid is called filtrate
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Purity
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Impure
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An impure substance is made of two or more elements or compounds that are not bonded together chemically.
If a substance has a small amount of unwanted substance mixed with it, the unwanted substance is called an impurity
Impurities in food additives or medical drugs may have harmful effects on human health. It is important that manufactured goods and drugs only contain the substances named
A liquid containing a dissolved solid will have a higher boiling point than the pure liquid solvent.
Pure
Paper chromatography, if only a single spot appeares on a chromatogram.
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