How to Demonstrate Diffusion

For chemistry teachers or students looking for a science fair project. How to demonstrate diffusion!

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Small bar of soap (hotel soap is good)
• 1 quart glass jar with lid
• Glue
• Paper
• Water
• Pencil
• Ruler
• A few weeks to collect data

1. Put the soap into the glass jar so that it will cover the bottom of the jar. Fill the jar to the top with water, and screw on the lid.

2. Glue a strip of paper on the outside of the jar. This will serve as your marker to collect your data. You will make marks on the paper. Use the rest of your paper to create your data table. One column for the date, and another column for the height (cm or in).

3. Screw the lid onto the jar. Set the jar aside where it will be undisturbed. Check the jar each week for several weeks. You will see two layers in the jar. the soap dissolves to form a heavy solution underneath the water. Each week, mark the soap's position on the paper each week. You will see the layer slowly moves upward.

Tips & Warnings

• What happens? First the soap dissolves in the water surrounding it. This is why you see the soap at the bottom. The molecules in the soap and the water are in constant motion and always interacting with each other. Eventually the soap solution distributes itself throughout the entire jar of water.