Sunday, February 21, 2010

Charles' Law/ Ivory Soap Soufflé

Ivory soap, the product of a manufacturing mistake, is filled with air bubbles. Therefore, unlike other soaps, it floats in water.  From www.stevespanglerscience.com/experiment/00000053
All soap contains water, both in the form of water vapor inside trapped air bubbles (particularly important in the case of Ivory) and water that is caught up in the matrix of the soap itself. The expanding effect is caused by the heating of the water that is inside the soap. The water vaporizes, forming bubbles, and the heat also causes trapped air to expand. Likewise, the heat causes the soap itself to soften and become pliable. This effect is actually a demonstration of Charles' Law. When the soap is heated, the molecules of air in the soap move faster causing them to move far away from each other. This causes the soap to puff up and expand to an enormous size. Charles' Law states that as the temperature of a gas increases so does its volume. 
Q: What did we use?
N's answer: We used two kinds of soap, a microwave oven (heat) and a pot of water.

Q: What did we do?
N's answer: First we put the Ivory soap in the pot of water and it floated because of the air pockets. The other kind of soap sank. Then we put the Ivory soap in the microwave. The heat made it expand.


Q: What happened?
N's answer: Ivory soap expands slowly into a big sculpture.

Q: What did we learn?
N's answer: Soap with air makes it float and heat makes the air bubbles fill with steam that make the soap grow bigger.

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