Homeschool Chemistry Lesson Plan ~ Make your own soap

Flickr Image by A*Kang

A great way to plan a lesson for home economics and chemistry is making soap. Students will use chemicals that react with fats and oils, through a process called saponification, to create real soap.

This project requires adult supervision and will require adequate protection for safety reasons.

You will need:

16 ounces of vegetable shortening
2 ounces of lye
6 ounces of water
Long Gloves
Eye Goggles
Napkins and towels for clean up
Spatula
Food scale or measuring cup
Vinegar to neutralize the lye
Storage pans
Soap mold
Stick blender

1. Start by weighing your 6 ounces of water and placing it in a large pan
2. Weight out the lye and slowly add it to the water while stirring until completely dissolved.
3. Rinse out the measuring cup with vinegar to remove any remaining lye particles.
4. Measure out the 16 ounces of vegetable shortening and place it into the lye solution.
5. Take your stick blender and blend the mixture until it gets thick; taking short breaks in between blends.
6. Once it has become thick, pour the mixture into a soap mold and let it sit for 24 hours.
7. Clean up your area with vinegar solution.
8. After 24 hours, the soap has hardened and you can now take the soap out of the mold.
9. Let the soap sit for about 2 weeks to allow it to dry and become more stable.
10. The soap is now ready to use.

Now it is time for your student to document their observations throughout the soap making process. Saponfication began when the oils mixed with the lye mixture and ended when the soap was fully hardened and ready to use. This is because the oils reacted with the lye in order for the oil and water to mix, which usually does not happen. Ask your student to complete the following questions in order to complete the activity.

• What special ingredients were used in this activity that you hadn't used before? 
• What happens when you normally mix oil and water together? What made it different this time?
• What causes the soap to harden?
• What do you think each ingredient you used does to the soap?
• What would you do differently next time to make the soap better?
• What do you think would happen if you took out one ingredient out of the soap? Lye? Vegetable shortening? Water?