Question

A limitation of using a nitrogen/vacuum double manifold is that only non-volatile substances can be present in the flask before the evacuation/ back-fill chcle is started. Volatile liquids and solids (low boiling point or evaporates easily) that can sublime must be added after the flask is under an inert atmosphere.

Explain why the above limitation if important to remember by describing what would happen to volatile substances during the evacuation cycle and the potential consequences for the reaction if the volatile substance was a reagent.

Answer 1

Vacuum indicates that low pressure.

According to Gay-Lussac's law, under vacuum (at low pressure), the temperature decreases.

As a result, the substance easily converts into the vapor state and evaporates.

Now, if the volatile substance was a reagent, the reagent does also start to evaporate.