Question

A chemist has a small amount of compound ( b.p. = 65 oC) that must be fractionally distilled. Yet, the Chemist does not want to lose any of the compound to hold up on the column. What the chemist should do?

Answer 1

To minimize compound loss during fractional distillation, the chemist should use a smaller column with appropriate packing, monitor the temperature closely, and collect the distillate promptly.

Step-by-step explanation:

To prevent the loss of a compound during fractional distillation, the chemist must manage the hold up on the distillation column. This can be achieved by using a smaller diameter column to reduce the surface area where compound loss might occur, ensuring the column packing is appropriate and does not absorb too much of the compound, and by carefully monitoring the temperature to prevent overheating which could cause the compound to degrade or stick to the column. Additionally, the chemist could use a column with lesser theoretical plates or trays, minimizing the volume within which the compound can be held up. In some cases, applying a slight positive pressure can also aid in pushing the last traces of the compound through the column. Lastly, the chemist should also make sure to collect the distillate immediately as it condenses to prevent loss through evaporation or degradation.

Answer 2

The chemist can either:

a. Use a small fractionation apparatus.

b. Add a compound with a much higher boiling point.

Step-by-step explanation:

Using a smaller fractionation apparatus or Vigreux column will help to minimize loss of the distillate.

If a compound with a higher boiling point is added, the vapors of this liquid will displace the vapors of this small amount of compound with a lower boiling point. This compound with a higher boiling point is known as a Chaser.