Home › Organic Chemistry › Technique Series: Recrystallization (urea as an example)
Steps
  1. 1 Understand recrystallization theory and methods 00:02
  2. 2 Extract urea from cold packs 08:09
  3. 3 Select appropriate recrystallization solvent 08:46
Organic Chemistry YouTube (Curated Tutorials)

Technique Series: Recrystallization (urea as an example)

Protocol
Difficulty
intermediate

Steps

1
Understand recrystallization theory and methods

Learn the fundamental principle that recrystallization purifies compounds by exploiting differences in solubility between the product and impurities at different temperatures. Review five main recrystallization approaches: single solvent with cooling, hot filtration for insoluble impurities, mixed solvent systems with constant proportions, anti-solvent precipitation, and vacuum evaporation techniques.

▶ 00:02
2
Extract urea from cold packs

Open two instant cold packs and remove the small water bag from inside. Pour all remaining urea pellets into a beaker, yielding approximately half a beaker of crude urea material.

▶ 08:09
3
Select appropriate recrystallization solvent

Identify the ideal solvent by researching or testing the solubility profile of the compound at both hot and cold temperatures. For urea, determine that approximately 1 gram dissolves in 1 milliliter of boiling 95% ethanol, making this the suitable solvent for recrystallization.

▶ 08:46
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