Crushing a Can and Floating Layers
Posted October 23, 2008on:
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.