General things

Question 1

What is the principle behind recrystallisation?

Answer 1

In impure substance is dissolved in hot solvent to produce a highly concentrated solution. As you cool the solution down, the desired substance crystallises first, leaving the impurities dissolved in the solution.

Question 2

What are the steps of a recrystallisation?

Answer 2

1. Dissolve impure substance in minimum amount of hot solvent to fully dissolve it.
2. Cool the solution to produce the crystals.
3. Remove crystals by vacuum filtration.
4. The crystals are left to dry.