How To: Perform Separation by Decantation in the Chemistry Lab

Find out how everything in a chemistry lab works, from pipettes to burners to recrystallization to storage. You'll get precise instructions on how to work and perform certain scientific duties in the chem lab, whether it's chemical or just ordinary high school science.

Watch this video on how to perform separation by decantation in the chemistry lab. As an example of how to separate supernatant from a precipitate by decantation, the movie explains the separation of iron(III) hydroxide.

Decantation is draining of supernatant by tilting the container. This technique is suitable when the precipitate is heavy and coarse. In this method, filtration of the supernatant and washing of the precipitate is also occasionally necessary.

How to Separate a Supernatant from a Precipitate by Decantation:

1. Put a stirring stick on the mouse of the container to avoid trickling of the liquid to the outside of the container.
2. Tilt the container and slowly decant the supernatant.
3. Pour suitable washing solvent to the precipitate and transfer the solvent by decantation. This operation is repeated a few times to wash the precipitate.
4. When the supernatant is needed rather than the precipitate, combine the original supernatant and at least the first washing solvent.