Science Smarts: Vampire soap

By Patty Rooks on October 4, 2025.

Well, I think fall has officially arrived this weekend. As I sit and write the article this week, the news is saying we are going to be dropping down into freezing temperatures. The signs of fall have surrounded me all week as the leaves have really turned vibrant colours and began to fall. What a better time than to continue with our fall/Halloween theme of science investigations. Let’s get started!

*Remember to ask an adult before doing this experiment.

Materials

– 1 bar of Ivory soapâ„¢

– Rubbing alcohol

– Measuring spoon

– Bowl

– Spoon

– Small jar with a tight fitting lid

– Laxative pills containing phenolphthalein (Ex-Lax)

– Safety goggles

Note: Only and adult should demonstrate this experiment.

Procedure

1. Put on your safety goggles.

2. Take two laxative pills and place them in a bowl.

3. With the back of a spoon crush the laxative pills up.

4. Pour the crushed pills into the jar.

5. Measure out two tablespoons of rubbing alcohol and pour into the jar.

6. Shake up very well.

7. Dip your hands on the laxative mixture, shake off and allow to dry.

8. Wash your hands with the bar of soap.

9. Watch what happens!

What is going on?

The soapy water should have turned bright red. This occurs because of a chemical reaction. The laxative pills contain phenolphthalein. Soap is essentially made by mixing together fats and lye or alkali. When phenolphthalein reacts with alkali (soap) and turns bright red.

Mark your calendars, our annual FAMILY SCIENCE OLYMPICS will be Saturday, Oct. 18 from 10 a.m. to 3 p.m. This is a FREE event BUT one adult must accompany all participants. I am looking forward to seeing you there!

Patty Rooks, senior scientific consultant Praxis Science Outreach Society. Praxis has moved! We are very fortunate to be located in the Community Futures Entre Corp Building at #202 556 Fourth St. SE, Medicine Hat, Alberta, T1A 0K8. For all your science needs, please email praxis@praxismh.ca.

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