Candy Corn Space Soap
No, this isn't how astronauts trick-or-treat, but it is an interesting and fun way to eat your candy. In this video Don Pettit explains how soap works using candy corn.
Soap is made of a bunch of molecules that have hydrophobic (water hating) and hydrophilic (water loving) ends. The hydrophobic ends repel water but are attracted to oil and the hydrophilic ends repel oil and are attracted to water. In the experiment Don Pettit performs in this video, he coated one end of the candy corn with oil, making it hydrophobic and then placed the candy corn in a water sphere. The hydrophilic end of the candy corn oriented itself toward the watery center, while the hydrophobic end stayed at the perimeter of the sphere. Every piece of candy corn that he added ended up in this orientation, hydrophobic end facing out and hydrophilic end facing in. After adding enough candy corn to the water sphere, it reached the critical micelle concentration, the point where no more candy corn could be added and the structure became less blob-like and acted more like a solid ball.
This is a model of how soap works. The hydrophobic ends of a molecule orient themselves toward the grease and the hydrophilic ends of the soap molecules orient themselves toward the water until the critical micelle concentration is reached and the grease is encased in a bubble. This allows the grease to be removed from dirty dishes or soiled clothing.
The International Space Station (ISS) may be a strange place to learn about how soap works, but Don Pettit makes it not only fascinating, but fun and tasty.
If you liked this, watch for more from Don Pettit from his next mission on the ISS coming soon here on PhysicsCentral.com
For more demos in space visit Don Pettit’s Saturday Science page from his mission to the ISS in 2003.