In chemistry, a suspension It is a type of heterogeneous mixture formed by one or more substances in solid state that are dispersed in a substance in liquid or gaseous state. In a suspension, the solid (dispersed phase) is not diluted in the liquid medium (dispersing phase). For instance: orange juice (since the pulp floats and does not integrate into the liquid medium), powdered medicines.
A suspension is a heterogeneous mixture because in it you can distinguish the particles that make it up. They tend to be unstable mixtures, since, due to their size, the solid particles in a suspension tend to settle easily when the mixture is at rest.
Characteristics of a suspension
- They are easily recognizable mixtures because they are usually opaque.
- Although they are usually made up of solid and liquid substances (mechanical suspensions), there can also be solid or liquid suspensions in gases. Also when we stir two immiscible liquids together, a suspension could form. An example of a solid substance dispersed in a gas is the aerosol.
- In different industries, substances such as surfactants and thickeners are used to prevent the solids in the mixture from settling.
- Many suspensions need to be mixed or shaken to return to their suspended state.
- They differ from solutions because the solid particles are larger, so they can be distinguished from those of the liquid, and in solutions the solid does dissolve in the liquid, giving rise to a homogeneous mixture.
- They differ from colloids because in these the solid particles are finer (diameter between 1 nanometer and 1 micrometer) and cannot be distinguished with the naked eye, but they can be distinguished using a microscope. In the suspensions, however, they can be distinguished with the naked eye.
- The substances that make up a suspension can be separated by physical methods such as filtration, centrifugation and decantation.
Examples of suspensions
- Dust + air
- Sand + water
- Oil + water when the mixture is stirred
- Mercury + oil when stirring the mixture
- Water + earth
- Volcano ash + air
- Soot + air
- Flour + water
- Chalk powder + water
- Milk of magnesia
- Horchata water
- Face cream
- Fluid makeup
- Hair spray
- Insulin suspension
- Amoxicillin suspension
- Penicillin suspension