A solution is the most common type of homogeneous mixture comprised of small particles that cannot even be seen with a microscope.  A solution must have one or more substances dissolved into another substance.  A solution will also never settle at the bottom of its container.  Vinegar and hydrogen peroxide are examples of solutions.

A colloid is a mixture of particles larger than the solution but too light to settle.  Fog is an example of a colloid.  Fog has tiny drops of water spread throughout the air.  Detecting colloids can be difficult, but shining a beam of light at a colloid will make the light scatter.  This scattering of light is called the Tyndall effect.  A suspension is a heterogeneous mixture containing a liquid where visible particles settle.  For example, Italian dressing and chocolate milk are suspensions.

Review:

1. Identify two characteristics of solutions.
2. What is a colloid?
3. Explain the Tyndall effect.