Question

Why are some organic compounds purified by distillation at low pressure?

• A. They have low boiling points
• B. They have high boiling points
• C. They are highly volatile
• D. They dissociate before reaching their boiling points

Answer 1

The correct option is D They dissociate before reaching their boiling points

The boiling point of a liquid is the temperature at which its vapor pressure is equal to the external pressure the molecules dissociate and form new molecules. So, to prevent the molecule from dissociation external pressure is reduced so that boiling point get lowered which prevent molecules from dissociation.

So, we use distillation under reduced pressure.