With the start of the weekend looming we thought we would share another silly and inexpensive science lab for you to play with in your spare time.  The Ivory Soap Souffle is an excellent demonstration of a physcial change.  You shove a quarter of a bar of Ivory soap (it has to be that particular brand) into your microwave and zap it for about 2 minutes.  When you pull it out it will look like mutant loaf of bread.  That' all you need.  A chunk of Ivory soap and a microwave, that's why it is high on Professor Tightwad's list of fun but cheap lab activities. Here you go:

Procedure
1. Place the 1/4 bar of Ivory soap inside the microwave.  Be sure to set it on a paper plate.  Set the microwave to cook for 2 minutes on the highest setting.  Punch “cook” and enjoy the show.  Be sure to monitor the expansion of the soap through the window.  If it seems like you are going to explode out of the microwave cut the cooking time short.

2.  Allow the soap to cool for a minute or two before touching it. Pass it around the room for the kids to examine.  Have them compare it to an uncooked piece of soap and record observations.

3.  Proper disposal requires a shower or bath. Yes, we are kidding.

How Come, Huh?
As legend would have it, Ivory soap was created quite by accident in 1890.  An employee at Proctor and Gamble, in the middle of mixing up a batch of soap, forgot to turn off the mixing machine before taking his lunch break. The additional mixing caused so much air to be whipped into the soap that the bars floated in water after they were produced. The response by the public was so favorable that Proctor and Gamble continued to use the new manufacturing method and the marketing department kicked into high gear with their new concoction as “The Soap that Floats!”
This same reaction actually is very similar to what happens when popcorn pops or when you roast a  marshmallow over the campfire. The air bubbles trapped in the soap/popcorn/marshmallow contain water. The water expands dramatically, about 1800 times when it is heated from a liquid to a gas.  This causes the rapaid expansion. This effect is actually a demonstration of Charles’ Law which states that the volume of a gas will expand proportionally to the temperature. It is also, as we mentioned at first, an excellent example of a physical change.