Solution, Colloid and Suspension
| Solution | Suspension | Colloid | ||
| Appearance | Clear, transparent and homogeneous | Cloudy, heterogeneous, at least two substances visible | Cloudy but uniform and homogeneous | |
| Particle Size | molecule in size | larger than 10,000 Angstroms | 10-1000 Angstroms | |
| Effect of Light Tyndall Effect |
none – light passes through, particles do not reflect light | variable | light is dispersed by colloidal particles | |
| Effect of Sedimentation | none | particles will eventually settle out |
none | |
In summary:
A solution is always transparent; light passes through with no scattering from solute particles, which are molecule in size. The solution is homogeneous and does not settle out. A solution cannot be filtered but can be separated using the process of distillation.
A suspension is cloudy and heterogeneous. The particles are larger than 10,000 Angstroms, which allows them to be filtered. If a suspension is allowed to stand, the particles will separate out.
A colloid is intermediate between a solution and a suspension. While a suspension will separate out a colloid will not. Colloids can be distinguished from solutions using the Tyndall effect. Light passing through a colloidal dispersion, such as smoky or foggy air, will be reflected by the larger particles and the light beam will be visible. A hydrocolloid can simply be defined as a substance that forms a gel when it is exposed to water. Such substances include both polysaccharides and proteins.