This is how chemistry demos are going to get banned in high schools:
Archive for the ‘High School’ Category
I was amused by a news story out of Florida, where a pair of disc jockeys were suspended after going on the radio Monday (April Fools’ Day) and reporting that the local water supply had dihydrogen monoxide in it. Unaware that dihydrogen monoxide is H2O, and H2O is water, many residents went crazy:
As if we needed any more evidence that science education in this country is absolute crap.
What’s more, the DJs might face felony charges. From a legal standpoint, I’m interested in seeing how this one turns out. I haven’t heard any direct quotes from the broadcast, but can you charge someone with a crime for stating a scientific fact? I’m assuming they were careful and said something along the lines of “there’s dihydrogen monoxide in the water” as opposed to “the water is poisoned with dihydrogen monoxide.” Anyway, I suppose the DJs went in with a fair amount of mens rea; what else did they expect to happen?
Those are some very colorful Group I halide salts you’ve got there, kiddos. Also, the word is “dissociates” …there’s no need to stick an “ass” in there, no matter how fun it is.
Sometimes it’s fun to look back and figure out how you got to where you are. When people ask me when it was I knew that I wanted to become a chemist, I always point back to when I was 15 and enrolled in AP Chemistry. The material was incredibly interesting, and my teacher posed questions to us unlike any other science teacher I’ve had. In addition to calculations, our homework problems had essay questions where we had to give thorough explanations in complete sentences. My friends and I would spend hours on the phone discussing things like Le Chatelier’s Principle and solvation effects in gory detail, then I’d hang up and spend the next hour writing paragraph after paragraph of explanation on sheet after sheet of college-ruled notebook paper. I have always enjoyed writing, and there was something especially satisfying about being able to think and explain instead of just crunching numbers. Dr. Liebermann also had us spend a lot of time in the lab doing all sorts of fun experiments, from precipitations of colored salts to the determination of the thickness of the copper coating on a penny. Chemistry has always appealed to me for its ability both to make stuff and solve problems/answer questions. Mathematicians and physicists don’t seem to get to make stuff as often as we do.
Anyway, the other day I was looking through some old photos and had to reconsider when, exactly, it was that I first fell in love with chemistry.
That poster of the periodic table has adorned my bedroom in my parents’ house since I was 9 or 10. Until I left for college, it was the last thing I saw at night and the first thing I saw every morning. My dad brought it back from the UK after a business trip; I believe it is a product of the Royal Society of Chemistry.
I must have cared deeply about the poster long before I had ever taken a class in chemistry. When my sister ransacked my room sometime in junior high school, she tore down the poster and ripped the hell out of it. Rather than put up something else, I took the time to mend the table and mount it on a foam board. You can see how the tape of my repair job has yellowed with age, but the table still hangs proudly in my old room as the first artifact of my chemical career. Today, you can buy similar posters for less than $20 on eBay, but I don’t think I’ll ever have the heart to throw my beloved, tattered one away.
As part of the outreach effort for our NSF Solar Fuels center at Caltech, we run a program that enables high-school students to conduct research using a Caltech-built kit to screen the activity of metal oxides in the photoelectrolysis of water (into molecular hydrogen and oxygen). During the summer, we host a select group of students to work on projects aimed at improving the kit and method. I briefly talked about my participation in the program before, and you can read more about it here.
On the last day of work this summer, aside from cleaning up the lab, we let the students select a few experiments from Bassam Shakhashiri’s fabulous Chemical Demonstrations series. The students I helped supervise selected the “copper-to-silver-to-gold” demonstration, in which a copper penny is plated with zinc (to appear silver) and then heated to yield a top layer of brass (which appears gold). The London Olympics could not have been better timed:
To my relief, the demonstration was remarkably cheap and easy to set up. All you have to do is grab a stock solution of NaOH, a bottle of zinc granules, and some pennies coined prior to 1983. (U.S. pennies dated before 1983 are composed primarily of copper, whereas more recent coins are copper-plated zinc.)
When you drop a penny into a beaker of zinc granules immersed in near-boiling 0.5 M NaOH, zinc will plate onto the copper such that the coin appears silver within two or three minutes. When the penny is washed and heated on a hot plate set to ~200-300 °C, the zinc and copper blend to form a brass alloy that is golden in color. This transformation happens quickly, within 20 seconds or so.
The zinc suspension can be used indefinitely; I think we plated around 15 pennies. The students had an assembly line going:
So, that’s it. The copper-to-silver-to-gold alchemy demo gets my full endorsement. It is cheap, easy, and a lot of fun. The students got to learn a little electrochemistry and materials chemistry, plus they all wound up with a cute conversation piece as a souvenir.
A concerned labmate brought my attention to a chemical abomination on last week’s episode of the increasingly unpopular television show House, M.D.
Thanks to a very special friend of mine, we can all enjoy video footage of what Hollywood writers believe constitutes a realistic demonstration for a high school chemistry class:
Marvelous, isn’t it? Notice how the teacher isn’t wearing a single piece of personal protective equipment—no gloves, no goggles, no lab coat—whilst working in front of a poster that reads “LAB SAFETY RULES”.
Who knows what this demonstration was supposed to be, but the last time I checked, HF wasn’t combustible. In fact, its NFPA 704 flammability rating is zero. Oh well, I doubt the flame coming out of the Bunsen burner is real anyway, seeing as how the dude just picked up the metal with his bare hands. The limp gas line and the fact that the blue flame doesn’t deflect upward when it is tilted are also nice pieces of laziness on the part of the production staff.
If you plan to replicate this experiment at home, I suggest that you work with hydrofluoric acid in plastic containers instead of glass ones. HF is a great etchant for glass and many other materials that contain silicon. Furthermore, if you have an accident and get HF on your skin or in your lungs, you are going to be in a world of hurt. That stuff is nasty and goes right for the calcium in your body. In the event of an accident, you should apply calcium gluconate gel to the affected areas of your skin and seek medical attention immediately. Preferably, not from Dr. Gregory House.