Question

Why is decantation considered unsuitable for separation of insoluble solids from a suspension?

Answer 1

Sedimentation: The insoluble solid particles are made to settle under the influence of gravity if they are large enough and the process of settling larger particles at the bottom of the container is called sedimentation.

Decantation: Once the particles settle down, the liquid part of the mixture is slowly separated from the settled particles without disturbing them and poured into a separate beaker. This process is called decantation.

• The problem with the separation of insoluble solids from a suspension is that there are very fine-sized suspensions that are not heavy enough to settle down.
• They keep floating on the liquid ass they have a lower density than the liquid.
• If decantation is used, these fine-sized lighter particles go along with the liquid part as they float on liquid during decantation making the process of separation by decantation futile.
• So, decantation is considered unsuitable for the separation of insoluble solids from a suspension.