Posted by: tpsciencefun | December 14, 2009

Colloidal Confusion

It’s a liquid, it’s a solid….no, it’s both!! How can that be? Well, in order to understand, I think you should do an experiment.  Follow the scientific method and see if you can make your own colloidal.

But first, a bit of background information about colloidal……………

Colloids have very interesting physical properties. One of the more interesting physical properties of colloidal materials is that sometimes they seem to be solid and other times they seem to be a liquid. Because of this odd behavior, colloids are called non-Newtonian fluids, because they break the rules of ideal fluids described by Isaac Newton in the 1700’s.

Colloidal suspensions respond differently to different forces, as seen in this cool Oobleck video by Blake (Kids Science, 2006). A fast, hard force will cause the colloid to appear solid, but a slow, even force will cause the colloidal material to flow like a liquid.

Ok, before you go any further, THIS MUST BE DONE WITH PARENTAL GUIDEANCE.  Also, it most be disposed of properly.  DO NOT PUT DOWN THE SINK OR TOILET.

Things You’ll Need

  • Cornstarch
  • Water
  • Bowl
  • Food coloring (optional)

Steps

  1. Place cornstarch in a container.

2. Stir in water.

For the desired consistiency, use about 2  parts cornstarch to one part water.

3.  Add a few drops of food coloring until you like the color.

4. Add more water to make it thinner or more  cornstarch to make it thicker.

5. Take it out and play with it!

Tips

  • Store in an air-tight container.
  • It is fun to try to roll your goo into a ball. If you try, it will just melt back into your hand.
  • If you put in food coloring: After washing your hands, you may notice a little bit of color left on your hands. Don’t worry. It should go away in a day or two.
  • Anything put into the slime (like little toy dinosaurs) can be easily washed with soap and water.

Warnings

  • Oobleck isn’t poisonous, but it tastes awful. Wash your hands after playing.
  • Wear old clothes, as Oobleck tends to get messy.
  • Don’t worry too much if it gets on something; it will come out with a little water.
  • Lay a couple newspapers on the floor so it doesn’t get all over the floor or table.
  • NEVER PUT DOWN THE DRAIN OR TOILET. IT WILL CLOG!
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