Soap in a tube? Why not! Typically when people make soap, they make a lot of it. However, you can make a small amount of soap in a test tube as a chemistry demonstration. This is a terrific example of the saponification reaction, plus it results in a product you can use.
- sodium carbonate (a home canning chemical)
- calcium oxide (used to control humidity, sold in home stores)
- sodium chloride (table salt)
- butter or lard
- 2 test tubes (or small heat-safe cups, if you don’t have test tubes)
- candle or alcohol lamp
- teaspoon or other measure
Make Soap in a Tube
- Add two scoops of sodium carbonate and 3 scoops of calcium oxide into a test tube.
- Fill the test tube about 3/4 full with water.
- Heat the test tube in the flame, but don’t bring the solution to the boiling point. As a safety measure, point the open end of the test tube away from your face. This is a good lab practice when heating any chemicals.
- Remove the test tube from heat and allow it to cool.
- When the liquid has cleared, add a pea-sized amount of butter or lard.
- Return the test tube to the flame. First, the butter or lard will melt. When it starts to mix with the water, add 6 scoops of sodium chloride.
- Carefully shake the test tube to mix the ingredients. The soap will rise to the top of the test tube.
- Allow the tube to cool and then remove the soap. If you rub it between your fingers, you’ll feel the characteristic slippery texture of your creation.
Last modified: June 11th, 2015 by