Let’s geek out: sulfur hexafluoride
Mykala and I saw some great science demos on Jay Leno; they were centered around a chemical called sulfur hexafluoride. Heretofore, I hadn’t heard of it. It has some really unique properties - for one, it’s a super dense gas, and so it flows like an invisible liquid. You can float boats (well, makeshift aluminum foil rafts) on it when it’s in a fish tank, and it puts out fires like no one’s business (which is the reason it is used in electrical installations). It is extremely non-reactive, not unlike Teflon or other perfluorinated hydrocarbons (though, it’s a sulfur compound). Anyhow, I got to looking it up on Sigma Aldrich, which is the chemical company I ordered chemicals from when I worked organic synthesis at St. Thomas. So, the 99.75% pure form of sulfur hexafluoride clocks in at a smidge over a dollar per gram. Mykala estimated the fish tank filled with the stuff was about 50 liters. So, let’s see… at STP, one mole of an ideal gas takes up about 22.4L… which means they probably used about 3 moles of the stuff. It weighs about 146 grams per mole, sooo that’s north of $450 in sulfur hexafluoride. I guess they don’t skimp for Late Night science demonstrations.
That said, there is one final property of sulfur hexafluoride that makes it pretty phenomenal: it deepens your voice. A lot. I didn’t believe it, but further research confirmed this to be the case. Watch the Jay Leno clip for yourself. They cut the explanation a little short, but David Willey (the scientist doing the demos) said the gas filters out the higher frequencies of your voice. He went on to talk about a Helmholtz resonator, which is not something with which I am too familiar. I can tell you, however, that resonance occurs when wavefronts reinforce one another. In the case of a Helmholtz resonator, this phenomenon can result in amplification of waves, due to sound pressure in an enclosed cavity (I think). What I can give you for sure, however, are examples of Helmholtz resonators, and trivia surrounding the term. For example, blowing air across a bottle, the body of a guitar, and those annoying mufflers that your neighbor installs on their car to deepen and enhance the exhaust note of the vehicle are all Helmholtz resonators. Furthermore, in Kurt Vonnegut’s book of short stories “Bagombo Snuff Box,” the band director’s name is Mr. Helmholtz, which I think is hilarious.
And now you know.
