Chemistry

Mixture Separation (continued)


Solids and liquids

To separate mixtures of solids and liquids, we can use the method of decantation and sedimentation, centrifugation, filtration and evaporation.

Sedimentation

It consists of letting the mixture stand until the solid settles at the bottom of the container.

Example: water + sand

Decantation

It is the removal of the liquid part, carefully turning the container. A settling funnel may be used to remove one of the components from the mixture.

Example: water + oil; water + sand

Centrifugation

It is the process of acceleration of sedimentation. A device called centrifuge or centrifuge, which can be electric or manual.

Example: To separate the muddy water.

   

Filtration

Mechanical process that serves to separate dispersed solid mixture with a liquid or gas. A porous surface (filter) is used to retain the solid and allow the liquid to pass through. The filter used is a filter paper.

Folded filter paper is used when the product of most interest is liquid. The filtration is slower.

Pleated filter paper produces faster filtration and is used when the most important part is solid.

Example: water + sand

Evaporation

It consists of evaporating the liquid that is mixed with a solid.

Example: water + table salt (sodium chloride).

In salt flats, salt is obtained by this process. In fact, evaporations result in coarse salt, which if purified becomes refined salt (table salt), which is a mixture of sodium chloride and other substances that are added by industry.