10. Separation by Decantation

General Remarks

As an example of how to separate a supernatant from a precipitate by decantation, the movie explains the separation of iron(III) hydroxide yielded in the following reaction which is carried out in "Inorganic Qualitative Analysis Experiment".
Fe3+ + 3OH- → Fe(OH)3↓
Decantation is draining of a 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 are also occasionally necessary.

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