Question

Name a substance which can be purified by crystallization

Answer 1

In case the substance is an amine and a salt, say phenethylamine hydrochloride, and its impurities are as free bases, the following procedure can be done in most cases: 
1. The substance should be put in an erlenmeyer flask or similar. 
2. Water should be added and the flask should be shaken so that the salt has dissolved. 
3. Naptha or similar non-polar solvent should be added (depending on the amount of impurities), and the flask shaken vigorously. 
4. The contents should be put in a separatory funnel and left there until two clear layers have formed. 
- Now the upper (non-polar) solvent layer should have all of the impurities, and the lower water-layer should have the desired salt 
5. The two layers should be separated, and the upper layer safely discarded.