Ochem students: you may remember today's brief discussion of the rules for assigning priority to groups around a chiral center. I promised I'd get back to you about an issue that came up in relation to this. I was unsure of myself on an issue surrounding what I think we can call a more-complex example. Well, I am disappointed in the textbooks in my office. None of them provide an explanation that is adequate to deal with the structure we were looking at in class. But there is a straightforward (if not simple) way to solve the problem.
And, as usual, it was I who was misapplying the rules and not our esteemed author.
Guess where I found a good description, illustrated with examples, concise, accurate, etc.? My favorite web source: Wikipedia.
Tuesday, January 13, 2009
Tuesday, January 6, 2009
Chemistry and Cookery, the Column
I discovered today that Harold McGee, author of On Food and Cooking, has a column available to read for free at the New York Times. Being an old fan I don't know how I missed this for so long, but I am quite happy to have found it! Links to the columns can be found most easily by starting at his website, Curious Cook.
Monday, January 5, 2009
oops.
Cyanide ion (CN-) and sulfuric acid produce HCN, a highly toxic gas. When inhaled, HCN interferes with celllular respiration and can lead to what amounts to molecular-level suffocation.
I am grateful to the writer and editors at the Oregonian for giving specifics on this accident. So often I see vague references in the media to spills or accidents involving chemicals, without actually naming them. As in, "a tanker turned over and spilled a toxic chemical...." ammonia? chlorine? xylene? The consequences of such spills can vary dramatically.
Good eye for the person who noticed the foaming, too. The evolution of the gas seems to have tipped him off to the fact that something was amiss.
Anybody know what they do with cyanide in a chip factory?
I am grateful to the writer and editors at the Oregonian for giving specifics on this accident. So often I see vague references in the media to spills or accidents involving chemicals, without actually naming them. As in, "a tanker turned over and spilled a toxic chemical...." ammonia? chlorine? xylene? The consequences of such spills can vary dramatically.
Good eye for the person who noticed the foaming, too. The evolution of the gas seems to have tipped him off to the fact that something was amiss.
Anybody know what they do with cyanide in a chip factory?
Friday, January 2, 2009
SciFri
Do you think radio lacks because it can not deliver video content? I must respectfully disagree.
Science Friday (from Talk of the Nation, hosted by npr) has a fantastic website that includes a library of videos that may even rival those of TED. At the moment I am particularly taken with the Hungry Scientist presenting carbonated fruit. But there is much more to explore. The Hungry Scientist blog also deserves checking out.
Suddenly winter break seems way too short.
Science Friday (from Talk of the Nation, hosted by npr) has a fantastic website that includes a library of videos that may even rival those of TED. At the moment I am particularly taken with the Hungry Scientist presenting carbonated fruit. But there is much more to explore. The Hungry Scientist blog also deserves checking out.
Suddenly winter break seems way too short.
Wednesday, December 31, 2008
watch your ash
npr broadcast a story about the coal ash spill in Tennessee this morning. The spill occurred a while ago but questions are persisting about the degree of hazard associated with the stuff. Bloomberg also has a story about this incident, but makes a more disturbing claim that wells in the area have been reported to contain levels of "some metals" that exceed safe levels. Yet EPA considers coal ash, which is produced in huge quantities at coal-fired power plants, a special waste that is recyclable into building materials, etc., not really a regular hazardous waste.
Is coal ash hazardous? Does the dose make the poison in this case? I don't have the answers but this story doesn't seem to be going away. Given time maybe the news media will deliver us some more good information. In the mean time I may have to dig into the EPA's web to see what else I can learn.
Tuesday, December 23, 2008
ahhhhhh, skiing.
It is finally ski season around here. I ventured out yesterday after applying a new coat of wax.
The wax I selected was the $12 version of red wax. This is the cheap stuff, often referred to as "hydrocarbon wax." The color of the wax indicates the temperature at which it is designed to provide optimal glide. There were other waxes at the store--yellow, blue, and purple, and there were more expensive waxes, too. Some were very expensive. How do they differ?
TOKO explains this on their web site. I do squirm a bit with their casual use of language and structures, but I appreciate their willingness to talk about these things in public! The waxes are color-coded for temperature mostly because the formulations need to vary based on how much liquid water is in the snow. Under warmer and/or wetter conditions, the wax will provide better glide if it is more hydrophobic. Warm temperature waxes are also softer. In cold and/or dry conditions there is less liquid water in the snow, so hydrophobicity becomes less important and the waxes are designed to be harder to stick well to the ski when the snow is cold, dry and abrasive.
Cheap waxes are mostly long-chain hydrocarbons. Wax can be made more hydrophobic by the addition of fluorine, which is expensive and therefore makes for faster but pricier waxes. Fluorinated waxes provide their benefits mostly under warmer or wetter conditions. The expensive cold-temperature waxes use graphite or molybdenum to reduce friction on the snow.
I love the pictures on TOKO's web page and I especially love the diagram that shows the measure of hydrophobicity by examination of the water droplet. But I have a hard time reading that fluorine is a molecule, and their explanation of what makes a good fluorine vs. a bad one looks pretty weird to me. More fluorine molecules in the wax? More high quality fluorine molecules? What? They're not sounding like chemists here, to me. It would be more appropriate to determine percent fluorine by weight, and make comparisons that way.
Maybe this is a bit of deliberate obfuscation to keep the public confused, in the same fashion as car companies advertising "miles per tank" instead of "miles per gallon."
The wax I selected was the $12 version of red wax. This is the cheap stuff, often referred to as "hydrocarbon wax." The color of the wax indicates the temperature at which it is designed to provide optimal glide. There were other waxes at the store--yellow, blue, and purple, and there were more expensive waxes, too. Some were very expensive. How do they differ?
TOKO explains this on their web site. I do squirm a bit with their casual use of language and structures, but I appreciate their willingness to talk about these things in public! The waxes are color-coded for temperature mostly because the formulations need to vary based on how much liquid water is in the snow. Under warmer and/or wetter conditions, the wax will provide better glide if it is more hydrophobic. Warm temperature waxes are also softer. In cold and/or dry conditions there is less liquid water in the snow, so hydrophobicity becomes less important and the waxes are designed to be harder to stick well to the ski when the snow is cold, dry and abrasive.
Cheap waxes are mostly long-chain hydrocarbons. Wax can be made more hydrophobic by the addition of fluorine, which is expensive and therefore makes for faster but pricier waxes. Fluorinated waxes provide their benefits mostly under warmer or wetter conditions. The expensive cold-temperature waxes use graphite or molybdenum to reduce friction on the snow.
I love the pictures on TOKO's web page and I especially love the diagram that shows the measure of hydrophobicity by examination of the water droplet. But I have a hard time reading that fluorine is a molecule, and their explanation of what makes a good fluorine vs. a bad one looks pretty weird to me. More fluorine molecules in the wax? More high quality fluorine molecules? What? They're not sounding like chemists here, to me. It would be more appropriate to determine percent fluorine by weight, and make comparisons that way.
Maybe this is a bit of deliberate obfuscation to keep the public confused, in the same fashion as car companies advertising "miles per tank" instead of "miles per gallon."
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