Thursday, August 23, 2012

Weird Science

Tuesday night, Gabe and I were at a local dollar store when he saw this crystal growing kit.  It was one of those things with two small rocks and a package of what looked to be purple sand.  You mix the sand stuff with hot water and pour it over the small rocks, and crystals are supposed to develop and grow. Well, the image of the crystals on the package reminded me of an experiment I found here.  This experiment is very simple and only requires a bar of Ivory soap and a microwave.  Easy enough.

What we are going to do is turn a bar of soap into foam.  Now, what defines a foam?  A foam is any material, liquid or solid, that traps a gas inside a cell-like structure.  Some examples of foam are whipped cream, shaving cream and Styrofoam.  This experiment will demonstrate closed-cell foam formation, physical change and Charles' Law (No Charles, not you.  I'm referring to Jacques Charles, and yes, I had to google it.) 

What I've read about this indicates this will only work with Ivory soap because other soaps don't contain as much whipped air as Ivory.  I have not yet tested this with other soaps, but that's on my to do list.  So, get a bar of Ivory and cut it into sections.  I cut mine into quarters, but you may want to go smaller depending on the size of your microwave.  Don't use an entire bar of soap as you may end up with a huge mess on your hands.  You've been warned.

Depending on the power of your microwave, the soap will reach its maximum volume within 1 to 2 minutes.  We microwaved ours for 1 minute, and it worked great.  It won't matter if you microwave the soap longer than necessary, nothing will happen once it has reached its full size.  My microwave smelled really clean for hours, though.  Yay!
How does it work?  There are two processes that occur during this experiment.  First, is heating the soap, which softens it. Second, you are heating the air and water in the soap causing the water to evaporate and the air to expand.  The expanding gases push on the softened soap turning the soap to foam.  Microwaving the soap causes a physical change, but there is no chemical reaction.

Charles Law states that the volume of a gas increases with its temperature.  This law is demonstrated when the micro waves heat the soap causing water and air molecules to move faster and farther away from each other which results in the soap foam. 

Allow the soap to cool for a minute or two before touching it.  The soap will feel flaky and brittle, but it's still soap.  You can wet it, and it will lather the same as before.  Now those of you that know my sons won't be surprised by this, but Garrett was really skeptical about using the foam.  He circled around it, checking it out but wouldn't touch it.  Gabe, the fearless, thought it was "way cool," broke off a piece and washed his hands.  When Garrett realized Gabe's hands had no obvious issues after using the soap, he reluctantly decided to try it.  HA!  Boys!

This is a simple project to try, that I thought I'd share.  Thanks to Making Memories One Fun Thing After Another for the idea to try this after reading about her kiddos trying it.