Soda can calorimeter by Flinn

In chemistry yesterday we set up the Soda can calorimeter experiment.  I found this set up a bit better than using a wire mesh sitting on top of the ring clamp. More heat was transferred to the can that way. The other modification that my colleague and I made was to use a watch glass and a large paper clip to put the food sample on for burning. The students really enjoyed the lab. I think everyone was fascinated to watch the cheeseballs go up in flames. The really do burn well compared to the marshmallows. Hopefully they will make the connection between the calories they consume and the unit of energy. The other nice thing about Flinn's write up is their easy to follow calculations set out step by step.

Particulate matter pollution

The ecology class took a look at pollution recently when we set out some PM (particulate matter) pollution detectors. Granted the EPA defines PM particles as between the range of 0-10 micrometers and what we captured is much larger but it gave us all an idea of the debris that is falling from the sky or being generated from the ground when disturbed by activity. So many of our students suffer from asthma that it is good to raise their awareness, and everyone else, of one of the many sources that can trigger an attack.

The detectors were made using a petri dish, a wax pencil to make a circle the size of a quarter, then a thin layer of petroleum jelly spread in the circle. We placed the detectors out for 48 hours and retrieved them. Unfortunately we had a rainstorm in between. I feared that would ruin our results but there was matter stuck in the petroleum jelly anyways. This is why you can see water droplets in the photos below. Under the dissecting scope (40x magnification) we could observe: dirt particles, pollen grains, tiny insects, and other debris. 

This detector was on the ground below an air exchange unit that is above on the roof.

Three of our detectors