A colloid is the tiny substance dispersed evenly throughout another substance. Colloids are one of three major types of mixtures, the other two being solutions and suspensions. The colloids can be in two different phases or states of matter. One substance is the dispersion medium such as water or gas. The other is the dispersed medium sometimes called the internal phase. This is usually tiny solid particles. If the medium dispersion is a gas, then the internal phase can be either tiny particles or tiny droplets of a liquid.
Examples of colloid:
- Milk is an emulsion, which is a colloid in which both parties are liquids.
- Shaving cream and whipped cream are colloids of gas inside a liquid.
- Gels, such as agar, jelly or even opals, are colloids of liquids inside solids.
- The red color of cranberry glass is caused by the reflection of light off gold particles in the glass. The glass is a colloid of solid particles inside the solid glass.
- Mud is a colloid of water and clay.
- Fog is a complex mixture in which air has both water droplets and solid particles. It may be colloidal in parts.
Colloid solutions can be classified into three:
- Emulsion: Emulsion is the mixture of liquids it is like if one liquid is constantly dispersed all through another liquid. An example of this would be mayonnaise or milk.
- Foam: The foam in this set is created by capturing the gas in a liquid. The substances which are dispersed would be the gas, triggering the fluid to become frothy and foamy. An example of this will be shaving cream.
- Sol: This is the third form is called a sol, which is when a solid is evenly dispersed throughout a fluid. Samples of soils include paint, blood and silver aquasols.
Classification of colloids:
Colloids can be classified in the form of substance which gets dispersed and must be larger than the size of a molecule but smaller than what can be seen with the naked eye. This can be more precisely quantified as one or more of the substances dimensions must be taken between one and thousands. Colloids are sometimes difficult to measure and because the colloids have an appearance to measure the solutions, colloids are sometimes identified and characterized by the physic-chemical and transport properties.