Experiment | How Does Soap Work?

Approximate time to complete: 10-15 minutes + questions and journal time

Experiment Card

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Purpose

We know that oil and water do not mix … but then how do we clean things with oil on them? I wonder what will happen if we add soap to the mixture.

Materials

• Test tube with cap
• Oil
• Water
• Soap
• Pipette

Procedure

1. Using your pipette, fill your test tube ¼ full with water. Then, fill your test tube to the halfway point with oil.
2. Put the cap on your test tube, and vigorously shake. Observe what happens.
3. Take the cap off of your test tube, and add 1 drop of soap to your mixture.
4. Put the cap back on, and vigorously shake. Observe what happens.

Questions & Further Research

1. What happened when you tried to mix oil and water? What happened when you added soap?
2. How do you think soap works?
3. What is an emulsion? Hint: this experiment involves emulsion.