Recrystallizations - Chemistry 218 Lab Recrystallizations...

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Chemistry 218 Lab Recrystallizations
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Impure Solids Pure crystalline solids are noted as having a sharp melting point. If the melting point is lower than expected and/or occurs over a temperature range, the solid is probably impure. Noticeable variations in color or consistency in the solid may also be indications of impurities.
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Introduction Recrystallization is standard laboratory technique for the purification of solid substances. Assumes that material to be purified is relatively clean, hopefully >90%. Also assumes that a suitable solvent is available for the process.
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Suitable Solvents The substance to be purified should have a high solubility at elevated temperatures. The substance to be purified should have a low solubility at low temperatures. Ideally, the impurities are either very soluble or completely insoluble.
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Dissolve in minimal hot solvent. Precipitate on cooling.
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This note was uploaded on 07/09/2008 for the course CHM 218 taught by Professor Loeffler during the Fall '08 term at Sam Houston State University.

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Recrystallizations - Chemistry 218 Lab Recrystallizations...

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