From left to right: Jeff Hepburn, Harvey Gendreau, Jean Hein, Jim Ross and Lew Brubacher at STAO 2008
It has been a sad two years for the ChemEd community. In February 2017, Jeff Hepburn passed away, and just this past summer, we lost Harvey Gendreau. Both were dedicated chemistry teachers who were full of knowledge, a willingness to share and an exceptional passion for chemistry. It would be impossible to recognize all their contributions to the chemical education so we decided to highlight a couple of their conference sessions taken from past issues.
Jeff Hepburn
CHEM-unicate CHEM-thusiasm
Jeff Hepburn was not only a chemistry teacher, he was also a professional magician. He frequently incorporated his magic into his teaching and demonstrations. Jeff strongly believed in the use of demonstrations for helping to increase students’ understanding of difficult principles. He also tried to keep his demonstrations simple enough so students don’t get so distracted by the WOW factor that they miss the reason for the demonstration. Here are some of the demos that Jeff presented at Chem Ed 2001.
Hard water???
Use a mirror glass (a glass that has two sides with a reflective divider, available in magic stores); place a black silk scarf on the back (unseen) side and sodium polyacrylate in the bottom of the front side. Pour cold, strong coffee from a soda can into the side with the sodium polyacrylate. Wait long enough to let it harden and then pivot the glass from the bottom so that the glass is upside down with the silk now facing front. Pull the silk out of the cup. Jeff then has the student hypothesize about what happened. He explains the magic behind this demonstration. This can be used for observational skills and/or a hydrogen bonding discussion.
Magic water bottle
With a diamond drill bit, drill a hole in the side of a glass flask near the bottom (Jeff actually used an old milk bottle). Place a plastic lid with a screen on the top of the flask. Cover the hole and fill the flask, through the screen, with water. Keeping your finger on the hole, tip the flask upside down rapidly and the water stays in the flask. The water will be released whenever you want by taking your finger gently off the hole. It can also be released by tipping the bottle off vertical center. This demonstration is good for opening a discussion on surface tension and air pressure.
Instant carnations
Take a Kleenex tissue and cut it at the bend. Fold it into accordion pleats and attach it to a pipe cleaner. Separate the ply layers and fluff it to make it look like a flower. Spray it with an indicator solution such as phenolphthalein or universal indicator and allow it to dry. When you are ready to do the demo, spray the flowers with an ammonia-based window cleaner and the flower colors will change. A time lapse will cause the colors to disappear. Be sure to wear your goggles and not to get any spray into your eyes. This is a GREAT way to demonstrate indicators and the effect of bases on them.
Flash flower
Make flowers like above, except with flash paper. Hold the flower at arm’s distance and touch it with a hot glass rod. The flower ignites immediately and completely. This demonstration is great for showing combustion reactions.
Jeff also mentioned many objects, available in magic shops that can be used for demonstrations. These included Flash Paper, Rupert’s Pearls, Dissolving Paper, Hot Book, Bubble Solution, Bounce/No Bounce Balls, and flash devices. Jeff’s ideas are useful, they make students think and they’re not too expensive.
Jeff Hepburn at ChemEd 2013 with Jo King (left) and Penney Sconzo
Harvey Gendreau
Harvey at a ChemEd 2013 session
ChemEd attendees will certainly remember Harvey for his engaging sessions, his humour and as one of the long-time organizers of the George R. Hague Jr AP Chemistry Symposium. Below is a reprint from Chem 13 News, January 2010, report by Jean Hein, current editor.
Crushing a barrel
At 2009 STAO (Science Teachers of Ontario conference) Harvey Gendreau did the “crush the can” demonstration with an 80-L metal barrel. He placed about 500 mL of water in the barrel, propped it up on bricks and heated it from below using a portable camping stove. Once a good-head-of-steam was produced, the stove was turned off, the barrel was sealed and allowed to cool. Given there was no ice bath available at the conference (you could use a kiddie pool filled with ice water), Harvey put some ice on the top and waited. About 10 minutes later the container imploded with an impressive bang. The picture of the resulting container is shown. He thanked the teachers from Weird Science who performed this demonstration at ChemEd 95 at Old Dominion University in Virginia where he first saw this done.
Where did Harvey get his drum? It was FREE. A nearby store (Barleycorns, www.barleycorn.com) is a place where you can make your own beer. The drum contained liquid malt and is generally thrown out with the trash. Harvey washed it out before use. Teachers are very creative in finding good (& cheap) sources!
Harvey also pointed out some great videos of this type of large scale implosion. Google “train, tanker, implosion” on youtube.com.
[Since 2010, the TV show MythBusters tried to recreate an implosion of the tanker train car. The premise of the demonstration is the tanker car was steam cleaned and then sealed up. Great video to follow up an implosion of a barrel — for those less ambitious, a soda pop can also works.]
Vacuum seal a students
Harvey Gendreau and Bette Bridges shrink wrapping an audience volunteer at STAO 2009.
Harvey also liked to vacuum pack teachers. This demo is simple. While holding one end of a vacuum cleaner hose, someone from the audience climbs into a clear giant plastic bag. The bag is pulled around the base of their neck to create a seal. Then the vacuum is turned on and the air is removed, causing the bag to shrink wrap around the lucky volunteer. At the beginning of the demonstration the pressure in the bag is the same as outside the bag. With the air removed, the pressure inside the bag is much less than the air pressure outside. This results in the bag tightly molding around whatever or whoever is inside. The volunteer can feel the sensation of being in reduced pressure.
[The demo was originated by Wayne Goates and presented many times at ChemEd conferences by Bob Becker.] JLH
