Wednesday, December 28, 2011

Separating Mixtures - Crystallization and Chromatography

-     - Used to separate two or more soluble solids from one another chemical solid-liquid separation technique
-     - This is a way of separating pure crystals from its solvent.
- a thermal separation and therefore a purification process that yields a solid product from a melt, from a solution or from a vapour.
- Two common methods of crystallization are “gradual cooling” and “diffusion”.
-     - based upon differences in solubilities
      - consists of two major events, nucleation and crystal growth
-     - one of the fundamental procedures each chemist must master to become proficient in the laboratory

- collective term for a set of laboratory techniques for the separation of mixtures.
- involves passing a mixture dissolved in a "mobile phase" through a stationary phase
- Chromatography may be preparative or analytical
- comes in many forms, e.g., paper chromatography, liquid chromatography, gas chromatography, ion-exchange chromatograph
- extensively used in the semiconductor industry, especially in the identification of contaminants that cause yield, quality, and reliability problems.
- can be used to distinguish between two very similar components
- Chromatography is the separation of water-soluble (colored) molecules (usually pigments) based on their different water solubility
- as discovered by Fransisco Edward Globohimer II

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