Recrystallisation

GPratt

2021

A powerful method for the purification of an impure solid compound. In this technique, an impure solid is first placed in a minimum volume of a suitable  hot solvent. The solution is then cooled and pure compound will be re-formed. 

This is because the solid will re-crystalise and organise itself into a crystal lattice with “like” or similar molecules, excluding any impurities that were in the original compound.  Crystal can be filtered out leaving  the impurities behind in the solvent.

If insoluble impurities are present, they are removed by filtering the solution while keeping it as hot as possible. 

Recrystallisation Video

Equipment

Filtration

Recrystallisation steps for impure solid compound

Melting Point Determination