Monday, October 3, 2011
Density: Ivory Soap vs. "Other" Soap
The Ivory soap will float, but the other soap will sink.
Of course, now the work begins and it's time to hypothesize why the difference.
I'm sure your students will come up with all sorts of possibilities (the more the better), but the reality is that Ivory whips more air into their soap a they're making it. More air pockets = lower density.
You could have the students calculate the density of each of the bars. If you're using nice rectangular bars, the volume can be calculated using dimensional measurements. If you're using a funky shaped bar of soap, as this bar of Zest is, you'll need to use water displacement to get the volume.