Experiment 3.1 Atmospheric Pressure
The students filled soda cans with water just enough to cover the bottom of the can,
then placed them in a frying pan that was on the stove on high heat.
We waited and waited........Nothing but smoke. We were looking for a
visible flow of steam coming from the cans, which we did not see...this time around anyway.
We tried the experiment anyway....
We first added the hot can right side up to a bowl of ice water....nothing fabulous to see here.
Next, the students put the other two cans upside down into bowls of ice water...again, nothing fabulous...
So we thought on it and decided we wanted to try again and change things up a bit...the 2nd time wasn't obviously the charm ,because we were disappointed once again...
So we made some changes. The students added more water to the cans and we used a smaller yet taller saucepan...this did the trick...when we noticed our steady stream of steam (say that 3x fast), we placed the can quickly upside down into the bowl of icy water and this is what the can looked like afterwards....
Pretty cool, huh? You would have thought something really exciting happened when this took place, cause there were shouts all around! LOL This is a lesson in itself, that you must try again and if something is not working, change it. The students did and they were successful!
What happened here :
The steam from inside the can pushed out all the air and when it was placed upside down into the icy water, the steam turned back into water and instead of being able to replace the air inside due to being under water, it crumpled due to the unequal air pressure that was bring exerted on it from the outside.
What we didn't realize :
The first couple of times we tried, we thought we were unsuccessful, but we really were, just not completely. If you noticed, when the first cans were placed upside down into the icy water, they did not crumple, because there was not enough steam built up, but the cans did suck up some water to replace what air did get pushed out. We seen this as we raised the cans and lots more water poured out than what we had in them.
Experiment 3.2 Seeing the Effect of Changing Temperature
For this experiment, the students filled a pitcher with ice water and held a liter bottle down in it for 5 minutes.
After the 5 minutes were up, we quickly placed a balloon over the lid of the bottle and placed the bottle outside of the pitcher to expose it to room temperature air...already we seen a change.
But then the students placed the bottle into a bowl of warm water and the balloon really inflated fast!
What happened here :
We sealed the bottle with the balloon while it was cold, trapping the cold air inside. As the temperature heated up, the air expanded and inflated the the balloon. Why did the air expand? The molecules that make up a substance (air) are constantly moving. When you added energy or heat to those molecules (cold air), they started moving much more quickly, bouncing off the walls of the bottle and pushing out the only pliable thing available, the balloon. So what looked like inflation, was actually the molecules moving more violently as the heat added energy to them. Neat!
We had a great group! I would still like to see less parent interaction as we progress. I realize we were working with the stove this time, but I believe the kids are mature enough to handle these experiments on their own. It helps them to retain the experience if they were directly involved, hands on. Plus, I enjoyed being able to step back and just enjoy the show!
No comments:
Post a Comment