In Junior High Scholl we have classified substances into two main groups; those are pure substances and mixture. Pure substances consist of elements and compounds, while mixtures consist of solutions, suspensions and colloids. In relation to our topics about colloids, the following are brief explanation about dispersion system, solution, suspension and colloids.
a. Dispersion System
When we mix two or more substances, the particles of substances mixed will spread or distribute their selves in the mixture. The spreading or distribution of those particles in the mixture called dispersion. Meanwhile, a chemical system consists of gas or liquid (as medium) and particles in it are called dispersion system. Example of dispersion systems is the sugar solution. In this case sugar is the dispersed substances, while water is the dispersion medium. Basically, the classification of mixtures into solutions, suspensions and colloids is based on the dispersed substance particles size.
b. Solutions
Solutions are defined as homogenous mixtures of two or more substance. The size particle of solute (substance that dissolved) is about 10-7 cm.
c. Suspensions
Suspensions are a dispersion system which consists of dispersed particles which are relatively large and they are evenly distributed in the dispersing medium. The size of dispersed particles can be observed by using ordinary microscope or by naked eyes.
d. Colloids
Colloid is used to represent all dispersion systems the particles of which have size (diameter) between 1 nm until 100 nm. Thus, colloid system is a mixture of substances in which are colloidal particles evenly distributed.
