Description of Technique/Process
Recrystallization is the process of purifying solids based on their different solubilities. The steps involved in recrystallization are:
a. Find a suitable solvent for the recrystallization;
b. Dissolve the impure solid in a minimum volume of hot solvent; c. Remove any insoluble impurities by filtration;
d. Slowly cool the hot solution to crystallize the desired compound from the solution; e. Filter the solution to isolate the purified solid compound. Types of Things Which Can/Cannot Be Purified in This Manner
Recrystallization can only be used on solid compounds that have a significantly different solubility from their impurities in any particular solvent. If their solubilities are too similar the impurities will still be mixed in with the compound even after undergoing recrystallization.
Labeled Diagram of the Required Apparatus
To recrystallize a substance you must have a test tube or beaker in which to dissolve the compound into the solvent. You must also have a heater with which to heat the solvent and get a saturated compound solution.
Two Real World Applications for the Technique
One real world use for recrystallization is in the creation of aspirin, making the substance pure and safe to be ingested. Another use of recrystallization is in metal, where old, stressed metal can be purified into a new, stress-free surface.
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