I blew some stuff up today

* This is the fourth post in my Countdown to NETA series.  My students and I will be presenting at the NETA conference this Thurday and I’m writing a daily post to supplement some of the things we’ll cover during the presentation (and some things we won’t).


I teach science and love it. There are so many fun things to do and always something new to try.  Today was one of those days.  Every year around this time we begin a chemistry unit in my 7th grade life science class.  Admittedly, chemistry is not my specialty and my brief stint as a pre-med major in college made that painfully obvious.  Nevertheless, I know just enough to be mildly deviant.

Over the summer I cleaned out the science lab at my school and discovered a small cachet of relatively harmless chemicals that were buried at the bottom of a closet where I kept all the lab coats. The 7th grade chemistry unit doesn’t get too deep, so I’ve never done more than simple labs with household chemicals.  As I prepared for this year’s unit, I broke out the newly found chemicals and did a little research to see what I could do with them.  One of the chemicals I had was Sodium Hydroxide (NaOH) which, I learned, reacts with Alumninum (Al) and separates the Hydrogen (H) as a byproduct. If you’ve ever seen the Hindenburg video, you know that Hydrogen is highly flammable. 


At the beginning of our lesson on physical vs. chemical changes, I announced that we’d be blowing something up if we finished our density lab.  The students finished the density lab in record time.  While they were completing the lab, I combined the NaOH and Aluminum Foil in a glass beaker.  I sealed a balloon over the top and after a few minutes the reaction really got going.  The beaker got hotter and hotter (exothermic reaction) and the balloon started to inflate.


At this point, the students started to disregard the lab and devote all their attention to  the beaker.  Up to that point, I didn’t think the reaction would work well enough for me to harness enough hydrogen in the balloon.   I quickly tied off the ballon and found a long wick so I could ignite the hydrogen without burning myself in the process.  The long wick was a very good idea and the resulting boom and fireball made the students go crazy.  It was the highlight of my school day and a joy to see the excitement on the students’ faces.  I didn’t have a video of it, but I’ve embedded one below that shows the basic idea.


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