Colloids
Colloids are mixtures formed by two or more substances, where the insoluble particles of one are microscopically dispersed throughout the other. Colloids always have a dispersed phase and a continuous phase (Figure 1).
Figure 1. An example of colloid: vinaigrette. Vinegar is the dispersed phase and olive oil the continuous phase. Image source : Vinagreta Catalana - Wikimedia Commons/ This image has been modified from the original.
Depending on the state of each phase, there are different types of colloids:
| Dispersed phase | Continuos phase | Type of colloid |
|---|---|---|
| Solid | Liquid | Sol |
| Liquid | Gas | Aerosol |
| Liquid | Liquid | Emulsion |
| Liquid | Solid | Gel |
| Gas | Liquid | Foam |
Due to the size of the dispersed particles, some colloids have the ability to scatter light in the so-called Tyndall effect.