The Separation of mixtures reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Separation of mixtures

In chemistry, separation of mixtures is the separation of the elements of a mixture. There are many principles that can be applied and they each have their strengths and weaknesses.

Processes

The main processes for separation of mixtures in chemistry are:

• Decantation - used when the mixture consists of substances of different densities. The less dense substances is carefully poured off of the more dense one.
• Filtration - used when one substance is a liquid and the other a solid or when one of the substances is soluble in a solvent and the other is not.
• Centrifugation - used when the substances have very similar densities, or when one of the substances consists of very fine particles suspended in a liquid.
• Distillation - used for mixtures of liquids with different boiling points, or for a solid dissolved in a liquid.
• Chromatography used to separate different dyes or pigments. A solvent travels through paper by capillary action and carries the pigments with it. Different pigments are deposited at different places on the paper depending on how much they like the solvent compared to how much they like to stick to the paper.
• Electrophoresis Organic molecules, such as protein are placed in a gel. A voltage is applied and the molecules move through the gel because they are charged. The gel restricts the motion so that different proteins will make different amounts of progress in any given time.

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