Archive for the ‘High School’ Category

The Copper-to-Silver-to-Gold Alchemy Demo

Friday, September 21st, 2012

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.

WWWTP? – HF Stupidity on House, M.D.

Tuesday, February 14th, 2012

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.

An Unfortunate Name

Thursday, January 12th, 2012

Logo for Solar Materials Discovery KitI mentioned in last year’s periodic table of cupcakes post that I go to a local high school about once a week to serve as a mentor for a program associated with Caltech’s NSF “Powering the Planet” center. A team of five students at the school synthesizes metal-oxide semiconductors on FTO-coated glass electrodes and screens these materials for catalytic activity in the photoelectrolysis of water. What makes the program so cool is that it’s not just a lab demo, it’s “real” research. There is a chance—albeit small—that we could happen across a great catalyst that will help solve the global energy problem.

When I started in the program, we used a scanning station assembled by a team at the University of Wyoming. They called the instrument “SHArK” for Solar Hydrogen Activity Research Kit and it had a cool shark logo and everything. Later on, one of the PIs at Caltech improved on the idea and built a second-generation scanning station that allowed for faster and more reliable screening. As with any new instrument, it came with a new name…the Solar Materials Discovery kit.

The benefits of the new kit were more-than-fair compensation for losing the cool shark mascot. At the beginning of this academic year, we discussed renaming the kit, but my suggestion of ORCA (Oxidation-Reduction Catalyst Assessment) was shot down. We ended up sticking with Solar Materials Discovery, or “SMD” for short. We have two SMD kits, SMD-1 and SMD-2, which my fellow mentors and I sign up to take to local schools for our weekly SMD activities.

So, that has been going on all year. Two days ago, I had lunch on campus with three former students who participated in the program when it was SHArK. These guys are back home from college and looking for trouble. Halfway into my meal of beef flautas, one of the students commented that the new name was weird and asked why we’d make such a ridiculous change.

“Why?” I asked.

“Ummm…because SMD stands for….ummm…suck my….”

Uh oh. I whipped out my phone to consult the Urban Dictionary, and sure enough, SMD is an accepted acronym for that vulgar phrase. And it’s not like this is an obscure, unpopular term—it has two thousand “thumbs up” votes for accuracy.

How on Earth did we all miss this? How did I—someone tuned into the worlds of technology and ribald humor—miss this?

For the past four months, I’ve been sending e-mails to sixteen-year olds asking the best time for me to come over for SMD. Caltech also has a Web site devoted to SMD, and we regularly give presentations discussing SMD and our SMD kits. I even designed that logo at the top of the post.

Ugh. Never have I felt so old…or dirty.

Why I Became a Chemist (?)

Thursday, July 19th, 2007

I’m still writing that introspective post, so enjoy this one instead.

When I think back on why I became a chemist, I always point to my 10th-grade chemistry class. Our teacher, Dr. Liebermann, was absolutely fabulous. He developed an engaging, rigorous two-year AP Chemistry course with great lecture notes and a detailed laboratory component. The focus was on really understanding the general principles at play, and the massive lab reports and essay questions on tests forced us to understand what was going on. A month into his class, I was certain that I would become a chemist.

But that decision probably had deeper roots. I knew that I wanted to go into math or science in 7th grade, when I had the legendary Vern Williams for math. Before that, in elementary school, I religiously watched Mr. Wizard’s World and would mess around with those experiments in our kitchen. Finally, this periodic table has dominated the landscape of my (old) bedroom since 3rd or 4th grade:

periodic_table_poster_big

With pictures and small blurbs about each of the elements, it’s still the best periodic table poster I’ve come across. My father brought it back from a trip to England, and I think the Royal Society still sells it. The yellowed pieces of packing tape are a testiment to the sentimental value I hold for the poster. I had to piece it back together after my sister ripped it in a violent rage circa 1992.

Whenever I go back home to Virginia and see the poster, I always chuckle at how funny it is that the periodic table was the last thing I saw at night for nine straight years, and sure enough, now I’m a chemist.

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Streitwieser and The Westinghouse/Intel Science Talent Search

Wednesday, March 14th, 2007

The finals of the Intel Science Talent Search ended last night in Washington, DC. Old fogies like me know the contest as the Westinghouse, a competition open to high school seniors who have completed scientific research projects. The girl who won top honors this year built an instrument for collecting Raman spectra, in her home, for $300. Now, if she would just go ahead and make a 400 MHz NMR spectrometer for ChemBark Labs, I’ve got a check for $400 with her name on it.

The Westinghouse/Intel competition has been running since 1942, and you might recognize some of the people who’ve reached the finals:

Andrew Streitwieser (STS ‘45)
Martin Karplus (STS ‘47)
Ronald Breslow (STS ‘48)
Walter Gilbert (STS ‘49)
Roald Hoffmann (STS ‘55)
Eric Lander (STS ‘74)
David Liu (STS ‘90)
Paul Bracher (STS ‘98)

Those are some pretty big names in chemistry. Andy Streitwieser’s story is particularly remarkable. It’s been about six years since I’ve read his autobiography, so I might have a couple of the details wrong, but it goes something like this:

Streitweiser and his friends loved chemistry so much that they built a rudimentary lab in his basement. While thumbing through the literature, he came across a JACS paper that described the reaction of fluorene with sulfuryl chloride but didn’t report the position at which the molecule was chlorinated. Streitweiser repeated the preparation and found that the melting point of his product matched that of 2-chlorofluorene, which had been reported previously. Maybe it doesn’t sound like such a big deal now, but it was 1944, he was in high school, and he was working in a lab that he built himself. You gotta love it.

Streitwieser wrote up his results, and at the tender age of 17, he published a communication/note in JACS. The institutional address printed in the journal was his home address in Queens. The only time I’ve seen something even close to as cool as that is when Gunter Wachtershauser listed his Yahoo! e-mail address on a paper in Science. L0Lzzz!!111!1!

Streitwieser would grow up to become a true hero in the field of physical organic chemistry, spending over 50 years on the faculty at Berkeley. He kept (keeps?) an entire print collection of JACS in his office, and before the advent of pubs.acs.org, it was not uncommon for students to stop by when the library was missing issues they needed. Even when Streitwieser was in his office, his secretary would tell the students to just go in and grab whatever they needed. Streitwieser, renowned for his intense concentration, would sit there like a statue despite being in the presence of someone rummaging through his book shelves. Weird.

Anyway, if you read through that paper from 1944, you will notice a familiar name in the acknowledgments: Ed Kosower. A classmate of Streitwieser’s at Stuyvesant, Kosower also grew up to become a fantastic chemist. They even co-authored a sophomore organic textbook together (with Clayton Heathcock). The book is superb, but it’s unfortunately out-of-print. I heard that the reason the fourth edition is the last is that the authors refused to acquiesce in the publisher’s wish to add color graphics. You’ve got to give those guys credit for not selling out the Old School.

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