Organic Chemistry

Question

Which distillation technique would provide the best method to separate bromobenzene from toluene?

a) simple distillation
b) fractional distillation
c) vacuum distillation

Answer 1

Hello Leigh.

 

Simple distillation is effective when the mixed liquids have a big difference in boiling temperature. Although what is considered big depends on what purity is desired, typically a difference greater than 25 K (or °C) is considered good for simple distillation.

 

Fractional distillation is used when mixed liquids have similar boiling points (differences typically less than 25 °C).

 

Vacuum distillation is used for liquids with very high boiling points (typically over 200 °C) or for substances that might react with oxygen when heated.

 

Bromobenzene has a boiling point of 156 °C, and toluene has a boiling point of 111 °C.

 

So, which technique do you think would be best?