Science in the Park ~ September 13, 2010

Ant Farm

If I remember correctly, this event was posted on ExploreandDiscover Yahoo homeschool group. It turned out to be really neat! Kiddos of all ages shared some of their different Science passions, and Julie, the coordinator, led two different experiments.

Cornstarch Suspension Science Experiment : "When we talk about "states" of matter, we usually talk about the three types:  solid (like a rock), liquid (like water) and gas (like the air we breath). A mixture of cornstarch and water make what is known as a suspension.  When you squeeze a Cornstarch Suspension it really feels like a solid because its molecules line up.  But it looks like a liquid and acts like a liquid when no one is pressing on it because the molecules relax.  This is another state of matter, called a suspension (It can act like a liquid, or, when pressed like a solid.)."

Rocket Science:

This week just happens to be National Aerospace Week, so it was super cool to be able to see a homeschool friend's rocket collection, hear a little about the physics of it all, and see live demonstrations! Sam volunteered and got to "push the button" when we came to "BLAST-OFF!" on the countdown. This collection included a rocket that needs a special air clearance permit to launch...WOW. I have a feeling we will be hitting the library for rocket science books, and building our own rocket very soon!

 

Tie-Dyed Milk:

"Liquids like water and milk have a property known as surface tension, due to the cohesive forces of the liquid's molecules. Look closely (you can use a magnifying glass) at the edge of the surface of water in a clear glass. Do you notice how the very edge of the water appears to rise up the side of the glass? That's because the surface tension of the water is actually pulling the water away from the glass inward toward the center of the surface. Soap will reduce this surface tension. Let's see what happens!".....

"You probably first noticed that the drops of food coloring just sat on the surface where you placed them. That's because food coloring is less dense than milk, so it floats on the surface, and the colors do not mix because you didn't stir the milk.
Then the action began with a drop of soap! The soap reduces the surface tension of the milk by dissolving the fat molecules, which is why fattier milk works better. The surface of the milk outside the soap drop has a higher surface tension, so it pulls the surface away from that spot. The food coloring moves with the surface, streaming away from the soap drop. Due to the convection that results from the moving surface, the food coloring may be drawn down into the liquid, only to appear rising again somewhere else. That's why it's best to use a clear bowl so you can see what's happening.
As the soap becomes evenly mixed with the milk, the action slows down and eventually stops. Addition of another drop of soap will start the process again." http://www.coolscience.org/CoolScience/KidScientists/tiedyemilk.htm

Lava Lamp Science Experiment:
"How does it work? First of all, you confirmed what you already knew... oil and water do not mix. The molecules of water do not like to mix with the molecules of oil. Even if you try to shake up the bottle, the oil breaks up into small little drops, but the oil doesn’t mix with the water. Also, food coloring only mixes with water. It does not color the oil.
When you pour the water into the bottle with the oil, the water sinks to the bottom and the oil floats to the top. This is the same as when oil from a ship spills in the ocean. The oil floats on top of the water. Oil floats on the surface because water is heavier than oil. Scientists say that the water is more dense than the oil."

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"Here’s the surprising part... The Alka-Seltzer tablet reacts with the water to make tiny bubbles of carbon dioxide gas. These bubbles attach themselves to the blobs of colored water and cause them to float to the surface. When the bubbles pop, the color blobs sink back to the bottom of the bottle. Now that’s a burst of color! Your own homemade lava lamp... groovy baby!" http://www.stevespanglerscience.com/experiment/00000035