Materials Required:
l Small bar of soap, not the kind that floats
l Glass jar with lid
l Glue
l Paper
l Water
l Pencil
Procedure:
- The tiny bars of soap from hotels or airplanes are excellent for this experiment, but if you don’t have any, slice a piece of regular soap into several chunks that will cover the bottom of the jar.
- Glue a strip of paper up the side of the jar. Then drop the soap into the jar, and fill completely with water.
- Screw the lid onto the jar and set the experiment in a quiet place where it will not be disturbed. Check the experiment every week for several weeks. You will see two layers in the jar. The soap dissolves to form a heavy solution underneath the water. Mark the soap position on the paper each week. This layer slowly creeps upward. Do you know why?
This Is What Happens:
At first, the soap dissolves in the water surrounding it. This is why you see the layer of soap solution at the bottom. However, the molecules of a substance are always in motion, even though the substance may appear to be sitting quietly. The soap and water molecules are in constant motion, always interacting. Eventually, the soap solution distributes itself throughout the entire jar of water. The scientific name for this process is diffusion.
