Posts Tagged ‘Kinetic Theory of Matter’
Today my Physical Science classes did two short labs in one period. Both of these mini-labs came from the book “Super Science with Simple Stuff!” by Susan Popelka. The book is geared towards middle school, but that never bothers me.
The first was using air pressure to crush a soda can. I was going to do this as a demonstration, but when I tried it this morning, the impact of the event was so powerful, I decided to have the kids do it themselves.
What you do is take a soda can and put about 1/4″ of water in it. Heat the can over a bunsen burner until the water is boiling. If you have a triangle support on a ring stand, it takes about one minute. If you have an asbestos wire mesh, it takes a couple more minutes. When the water in the can is boiling, use tongs and invert the can into a bowl of water. The can implodes instantly and dramatically. I’m a jaded science geek and it impressed me. The kids absolutely loved it. I had extra cans so they could do it again, they used up all my cans in both my classes.
The second lab uses Corn Syrup, Water, Vegetable Oil, and Rubbing Alcohol. I used a 250ml beaker and had them put 50ml of each liquid. First the corn syrup, then the water. Before adding the water, they added a drop of blue food coloring. Next they added the oil, but poured it over the back of a spoon so it would cause the layers to mix. Last the alcohol with a drop of red food coloring, again poured in over the back of a spoon. You get four very distinct layers. Then use random items to see if they float in between the layers. I used wooden toothpicks, bits of a plastic spoon, beans, and bits of Styrofoam from a cup.
The kids all commented how cool the lab was today. They enjoyed it and were really excited.
Today I had to lecture on the Kinetic Theory of Matter in my Physical Science class. It’s all about how the particles of matter are constantly moving, even in a solid. I came up with three demonstrations that you might want to borrow.
First was discussing the nature of atoms being packed together in a solid. I have a plastic jar of marbles. Students can see how the marbles all nest together in the jar. I gently rattled the jar to have them understand that the molecules (marbles) are in constant motion, even in a solid. I then poured the marbles out into a box lid. I showed how they poured just like a liquid, still took up the same volume, but flowed like a liquid and took the shape of the container like a liquid.
The second demonstration was simple. I lit a match in the corner of the room and we waited while the smell found it’s way across the room to the students at the far end. I used that to talk about how the molecules are moving very rapidly but bumping into one another, so it takes time for the smell to dissipate.
The third demonstration was the best of the day. I put a beaker of water on the overhead projector and let it sit to remove turbulence. I then carefully and gently added a drop of food coloring. Because it was lit from underneath, the kids could see the snake-like tendrils working up and down and on the overhead they could see the color spreading out. After watching for only a couple of minutes the color was mostly uniform. They made me add additional colors and watched them swirl.