Kitchen Chemistry Experiment 20
Slime or Oobleck

Non-Newtonian Fluids and Colloids
Many of the materials we use every day, like starch, are made up of molecules called POLYMERS. POLY means many and MER means unit. Because the units in chains are so long, they interfere with the ability of the solution to flow. Viscosity is a physical property of liquids that descibes how they flow. Honey and corn syrup are described as having high viscosities because they flow more slowly than water

 

 

Materials	Substitutions
1 500 mL beaker	1 bowl
1 /2 box of cornstarch	1 cup cornstarch
a spatula	a spoon
1 aluminum pie pan
scissors
water

Procedure

1. Pour 1 cup cornstarch into a bowl or beaker.
2. Continue to add a small amount of water until the solution begins to thicken. Stir carefully! Don't fight the viscosity of the slime.
3. Pour some of the slime into the pie pan. Try to cut it as you pour. Slap the top of the slime in the pie pan. Pour some slime into your hands and roll it into a ball. Does the ball keep its shape? Make a slime snake and pull it apart quickly. What happens? Draw in the slime with your spoon. Write your name.

 

Extensions

Try making on of the other non-Newtonian fluids in this lab manual. See GLURCH or SILLY PUTTY.

Teacher's Notes

1. The slime is a non-Newtonian fluid --so-called because of its unusual viscosities. A non-Newtonian fluid has properties of both a solid and a liquid and reacts to stress with increased viscosity.
2. Slime can make a mess!! Be prepared for your students to have some "play" time. Towels and water should be on-hand as bits of slime will be on countertops.
3. If you have ziptop bags, you could allow the students to take their slime home with them. Warn them that slime will only last a few days, at best. Then it will get moldly and should be discarded.
4. If you are doing this for elementary age students, you may want to add a drop or two of food coloring (thus creating a oobleck!). Then you can read Dr. Suess' "Bartholomew and the Oobleck".
5. Slime can be spead onto a cookie sheet and dried so that it is recycled!!
6. Amylose (cornstarch) and water can be considered a colloidal suspension. A colloidal suspension is a two-phase system where the starch and the water are not dissolved but simply MIXED into a permanent suspension that will not settle on standing.
7. Other examples of colloids are: blood, fog, whipped cream, foams, jello, and styling gels.