Final answer:
A gas bubbler is used in vacuum distillation to prevent bumping (B) and to allow the introduction of inert gas for distilling air sensitive materials (D). It is not meant to reduce the vacuum effect (A) or push the vapor through the system (C). Options B and D are the correct answer.
Step-by-step explanation:
When conducting a vacuum distillation, a gas bubbler may be inserted into the apparatus for several reasons, and it can serve multiple functions:
- B: To help prevent bumping, a phenomenon where a solution in a distillation flask superheats and then rapidly boils, causing eruptions of the liquid - a potential safety hazard and a threat to the purity of the distillate.
- D: An inert gas can be incorporated via a gas bubbler, which is particularly valuable when distilling air sensitive materials. This introduces a protective atmosphere and prevents the materials from reacting with oxygen or other gases present in air.
A gas bubbler is not used to reduce the effect of the vacuum (A) or to push the vapour through the system (C), as the purpose of the vacuum is to reduce the boiling point of the substance being distilled, and the vacuum itself facilitates the movement of vapour.
In summary, the correct options regarding the insertion of a gas bubbler into a vacuum distillation setup are B and D.