What is decantation ?
consists in waiting that, in a heterogeneous mixture, constituents
separate one each other spontaneously.
2) Example: decantation of a
mixture of water and soil
shaking the mixture, the soil particles are dispersed in
We then observe:
- A layer of soil forms slowly to the bottom: it consists of particles
that fall as a result of their weight.
- The liquid gradually brightens. Less dense particles fall slower.
- After a sufficiently long time, the liquid becomes clear since all
particles have fallen to the bottom of the beaker.
Advantages and drawbacks of decantation
is a simple separation to implement since it requires no special
equipment but obtaining a complete separation and a totally clear
liquid can takes a long time (sometimes several days) if the
particles mixed to water are thin and of low density.
- The separation of water and oil after shaking also corresponds to a
decantation ( the only difference being that the
oil rises to the surface ).
- Decantation also occurs in nature when water is mixed with soil or