The term colloid is used to define that substance that, when meeting a liquid, gradually disperses. This can be composed of two fundamental phases: dispersing or dispersing, in which it is a fluid or continuous substance; and the dispersed one, is composed of the colloid particles. It also has a colloidal system, they can become dispersed in the dispersing phase. In certain cases, the dispersing phase is not a liquid, but a matter in a different state of aggregation.

what is colloid

They are mixtures formed by solid particles that are dispersed in a substance. This duality is known as phases, in which its solid form is known as disperse phase, composed of colloid particles; while the dispersing or dispersing phase corresponds to the fluid part of the mixture, also known as continuous or the medium in which it is dispersed.

Colloid chemistry is the science that is responsible for studying it and taking advantage of its application and this information can be obtained online where there will be PDF colloid files.

The importance of colloids lies in their great utility in the food industry, paints, medicines (such as colloid bath, colloid patch), detergents, among others.

Then, it is an inhomogeneous system. Due to the force of attraction between the dispersing phase and the dispersed phase, therefore, these present different characteristics and receive different names, some are gel, foam, aerosol, among others.

Its etymology comes from the Latin colla and the Greek kolla, which mean “glue glue” and the Greek suffix eides which means “similar to” or “in the form of”, which in this sense together means “similar to glue glue”.

Characteristics of colloids

  • Colloid particles are microscopic and therefore cannot be seen as easily.
  • They differ from suspensions, whose particles are visible without resorting to a microscope.
  • While suspensions can be filtered, colloids cannot.
  • The particles of these will not separate even when they were at rest.
  • Its Brownian motion prevents its particles from settling.
  • It presents the Tyndall effect, which is when a beam of light passes through the mixture, exposing the particles.
  • One of its properties is that of adsorption, in which it can maintain on its surface the molecules of gases, solids or liquids that are dispersed in the solution.
  • Its electrophoresis property allows its molecules to be separated according to their mobility in an electric field.
  • Its dialysis property allows the molecules of their solution to be separated by the difference in their osmotic pressure indices through a semi-permeable membrane, as a filter.

Colloid phases


dispersive phase

It is the solvent part of the mixture, where the solid particles are dispersed. It is characterized by being fluid or continuous, although it does not necessarily have to be liquid and it is the most abundant part of the mixture.

disperse phase

It is the part of the mixture that is dissolved, made up of relatively large particles that will not settle because they are constantly moving.

colloidal systems


This consists of one liquid in another with which it cannot be dissolved or mixed. In this case, both the dispersed and dispersing phases are liquid.


They are those in which the solid particles are dispersed in liquids, presenting viscosity and plasticity. According to the attraction that exists between their phases, they can be lyophobic (little attraction between the dispersed phase and the dispersing phase) or lyophilic (great attraction between the dispersed phase and the dispersing phase). An example of this type is colloidal silver.

Aerosol sprays

Its liquid or solid part is finely divided into a gaseous disperse phase.


It is a sol that has gone through a gelation process, which consists of gradually increasing its viscosity.


This is characterized in that its dispersed phase is a gas and its dispersing phase is a liquid or solid.

examples of colloids

The importance of these lies in their usefulness. Some products that belong to or are structured by them according to their type are:

  • Emulsions: milk, mayonnaise, cream, butter, dressings.
  • Suns: paints, ink.
  • Aerosols: clouds, fog, smoke.
  • Gels: jellies, jellies.
  • Foam: shaving foam, whipped cream.

  • Other examples according to their composition are: continuous gaseous phase fog, smoke or environmental dust; continuous phase liquid cream, shaving foam, paints, creams; solid continuous phase meringue, gelatin, ruby ​​crystals.

Colloid FAQ

How to make a colloid?

It can be done by disintegration by breaking large particles down to colloidal size (eg grinding the particles), or by condensation by promoting aggregation of a true solution to colloidal size.

What type of mixture is a colloid?

It is a kind of heterogeneous mixture.

Why is blood a colloid?

Because it is made up of a solid phase, made up of white and red blood cells and platelets, and the liquid phase, which is plasma.

What is the colloidal state?

It is the state of matter in which its solid component is dispersed in its liquid or gaseous component, and both states can be differentiated.

What is the difference between a colloid and a solution?

A solution is a homogeneous mixture (its components are well dissolved), while a colloid is a heterogeneous mixture since its solute is not well dissolved in its solvent and can be easily differentiated.