This blog is my attempt to reconnect with the world of chemistry. I have a PhD in Inorganic Chemistry and make a living doing research for a large company in Michigan. As times have changed, that company has changed its focus and I no longer have as much chance to do the basic, fundamental research which I most enjoy. Through this blog, I am hoping to recapture the magic which I felt during my graduate (and undergraduate) days in college. Expect topics on chemistry and alchemy along with some non-chemistry related items which I think might be interesting.

"The chymists are a strange class of mortals, impelled by an almost insane impulse to seek their pleasure among smoke and vapour, soot and flame, poisons and poverty; yet among all these evils I seem to live so sweetly that may I die if I would change places with the Persian King."

Johann Joachim Becher (phlogistonist)
Acta Laboratorii Chymica Monacensis, seu Physica Subterranea, (1669).

Wednesday, April 2, 2008

H2S ------ Sorry, Couldn't Think of Anything Snazzier

H2S is a colorless gas with a rather distinctive smell. Its odor is often described as being similar to rotten eggs, but I cannot verify that personally because I've never come across a rotten egg. On the other hand, I have worked with H2S off and on over the years, so I do know what it smells like. H2S is quite poisonous, significantly more toxic than hydrogen cyanide, but due to our nose's ability to detect it at ppb levels, it's rarely deadly. Safety note: since your nose is quickly desensitized to H2S, it can still be deadly if you aren't paying attention.

H2S has been in the news lately, in a Jekyll and Hyde sort of way. Peter Ward, an expert on mass extinctions, has been discussing the role of H2S in many of the known mass extinction events which appear periodically in the fossil record. The theory is that during times of global warming brought about by raising CO2 levels (usually as the result of massive volcanic activity), ocean circulation stops, which results in a huge drop in its oxygen content. This allows H2S producing bacteria to take over the oceans, eventually choking off the oxygen and wiping out most of the planet's species.

Despite this rather negative press, other researchers are beginning to find that in small doses, H2S can be beneficial when used to slow down the metabolism of mice. In one study, this technique is shown to be useful in minimizing the damage caused by heart attacks. In another study, H2S is being used as a means of possibly inducing suspended animation.

Using H2S to slow down a person's heart freaks me out a little, mostly because it almost killed my roommate in grad school. My roommate was performing a synthesis in a hood using an H2S tank when, somehow, the regulator malfunctioned (or broke) during the reaction, venting gas directly into the hood. In order to shut it off, he had to hold his breath, raise the hood, and close the H2S tank with a wrench. In hindsight, he should probably have just let the tank vent, but in the process of closing the tank he ended up taking a breath or two. He mentioned feeling a little woozy and I walked him out into the hall whereupon he collapsed onto the floor, unconscious. While someone else called the university emergency number, I stayed with him, although I wasn't exactly sure what I could do. His breathing started getting ragged, which scared me, but it was even scarier when his breathing appeared to stop. I tried giving him mouth to mouth resuscitation, but I had difficulty forcing air into his lungs because his teeth were tightly clenched. Fortunately, he regained consciousness about a minute or two later, just in time for the fire department to show up. We tried explaining to the firemen what had happened but they didn't really know what H2S was and were more interested in finding a chemical spill onto which they pour sodium bicarbonate, which apparently was the sum total of their training. Eventually they noticed a red spot on my roommate's forehead, no doubt due to its hitting the floor earlier, and satisfied themselves with pouring baking soda on him, despite our assurances that it wasn't necessary.


Ψ*Ψ said...

Seriously? They actually poured bicarb on him?!

Liberal Arts Chemist said...

Now that was a cool story about H2S, your friend is lucky. I attended a conference in Alberta, Canada a few years back where one of the activities was going to a plant where they stripped sulphur from the sour gas common in the area. It was pretty amazing and a great demonstration of the Claus and Ostwald processes. One issue though was that they had had several deaths caused by H2S poisoning due to beards. It seems that when H2S leaks occured everyone put on full face masks but men with beards could not get a leak tight seal to the skin and the H2S would reach toxic levels even with the mask on. That meant the plants all had a no beards policy which resulted in me having to shave off my full Mountain Man beard in the middle of summer. I had a very peculiar tan line for a few days.

Chemist Ken said...

Yes, they actually poured bicarb on him, despite our assurances that it wasn't necessary. That was a running joke in our lab for weeks.