Good
Clean Fun
This show demonstrates some of the properties of water. It also looks at how these properties are affected when different materials are added.
· Toothpick tricks
· Indy card race
· Nonburning towel
Toothpick Tricks (Hands-on)
A circle of toothpicks move in and out when different materials are added.
Reference: “Simple Science Experiments With Everyday Materials,” by Muriel Mandell, Sterling: New York, 1990; p. 111.
Fill a lid or shallow pan just high enough to cover the bottom with water.
Place a circle of toothpicks on the water so they are arranged like spokes of a wheel without a hub cap.
Add some soap to the middle of the wheel and observe what happens.
Replace the water in the pan and place the toothpicks as before.
Add a sugar cube to the middle and observe what happens.
Explanation: When soap is added to the middle, the soap spreads out a thin film by reducing the surface tension and carries the toothpicks with it. When the sugar cube is added, it absorbs the water and the toothpicks are carried toward the cube by the current produced.
Tips: Have students work in small groups and guess what will happen when the soap is added. Have them discuss what they observed and predict what will happen when the sugar is added. When all the groups are finished, ask the groups what happened and have them try to explain what they observed. Some groups will not get the same results as others. Have a discussion about this.
Questions Students May Ask: What is surface tension?
Index cards race across water.
Reference: “Simple Science Experiments With Everyday Materials,” by Muriel Mandell, Sterling: New York, 1990; p. 110.
Cut out a boat from an index card that measures approximately 2” x 1” with a small slot in the rear large enough to pass a quarter through without touching the card. Float the boat in a large shallow pan or pot of water and pour some detergent into the slot. Observe what happens.
Explanation: The soap reduces the surface tension behind the boat propelling it forward. It will stop when the surface tension of all the water is reduced.
Tips:
Towel burns without being consumed.
Reference: “Chemical Demonstrations, Volume 1,” by Bassam Z. Shakhashiri, University of Wisconsin Press: Madison, 1983; p. 13.
“Chemical Magic from the Grocery Store,” by Andy S. W. Sae, Kendall/Hunt: Dubuque, 1996; p. 65.
Make an aqueous solution of 50-55% isopropanol and pour into a shallow pan.
Soak an ordinary paper towel with the solution.
Gently squeeze the towel so no more solution is dripping from it.
Hold the towel with crucible tongs and light it with a match.
Ask a volunteer from the audience or another student for some money and repeat.
You may also use the palm of your hand but caution should be taken since it will get very hot. Do not let the flame go out by itself! Quickly shake your hand or blow out the flame after a second or two.
Explanation: Most of the heat from the combustion of isopropanol is given off to the environment. The remaining heat is absorbed by the vaporization of the alcohol and water. As long as there is enough water present the material will not burn and the flame will continue as long as there is alcohol to burn.
Tips: