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."

Monday, December 15, 2008

gifts for the chemists in your life

1. On Food and Cooking, by Harold McGee. A classic connecting science and cooking, but in that order. Other books in the sub-genre of Science of Cooking often read more like cookbooks. Fun ones, yes, but cookbooks. McGee's is a science book.

2. Scientific playthings, especially interesting materials. Some of my favorites are magic sand, insta-snow, and and Sculpey, which is bakeable polymer clay. I've also seen some very un-dense baked clay, but I don't know what kind it is. It's almost foamy. The piece I saw was sculpted into a beautiful brain and spinal cord, and the entire life-sized brain was one solid piece. I haven't had much luck baking larger pieces of Sculpey.

3. Do it at home: massive quantities of baking soda and vinegar are inexpensive and no further away than the grocery store. Boil a little red cabbage in a small amount of water to produce a pH indicator solution that you can use to test any of a number of household items: soda, vinegar, baking soda solution, clear soap solutions, etc.. Some groceries also sell dry ice, which is fun to play with provided you are careful. Dry ice in a sink of warm water with soap bubbles is super entertaining. It is possible, I have heard, to remove the superabsorbent polymer from a diaper. If you cut open the liner and get the stuff separated out I bet it could be fun to mess around with.

4. Kits that allow the average kitchen to feel more laboratory-like. New England Cheese Making Supply has intro kits that allow you to produce a nice Mozarella in less than an hour. Craft stores sell kits for soap-making. Edmund Scientifics sells root beer and hot sauce kits. If you have a local brew-supply store you can find not only beer-making kits, brewing supplies that can be used regularly if you think you'll get into that, and also soda-making supplies that often allow you to choose which kind of soda you want to make. Typical options include cola, creme soda, and sarsaparilla.

'tis the season.

Friday, December 12, 2008

What the heck is caffeol?

A book that I own called Chemistry and Cookery, published in the 1930s, has a great section about coffee that is fun to read as a chemistry book and as a piece of history. It has a big section about coffee preparation methods, all written well before most people were drinking coffee brewed with an automatic drip coffeemaker, let alone having access to espresso.

The discussion includes frequent reference to an oil called caffeol, which the authors refer to as a volatile oil that is easily lost through extended heat, boiling, or long storage especially in an open container. What is this caffeol, I wondered, and why do I not hear it referred to by those who wish to advertise their beans as the best available?

I went to Wikipedia. I found a single mention of it as a volatile oil responsible for flavor and aroma in coffee, but with no structural information.

So I googled "caffeol." I found numerous references to it as a volatile oil responsible for flavor and structure.

So I googled "caffeol structure," and found a book excerpt (thank you google books!) from Coffee Flavor Chemistry by Ivan Flament and Yvonne Bessier-Thomas that actually gives caffeol a bit of attention.

What do they say? Lots. It takes several pages (starting at about page 61), and they're complicated and it's late and the story is long and meandering. But what grabs me as I look at the pages from the book is that there are two tables listing what must be about 20 compounds identified in coffee aroma. I also know nobody has managed to bottle an artificial version, so we have probably not worked out the composition of the entire mixture. Nothing smells quite like the real thing.

I am putting that book on my Christmas list.

Monday, December 8, 2008

those of you who are in to combustion, read on

The Christian Science Monitor has an article about a guy who has developed a stove to burn rice husks efficiently, potentially improving the quality of life for people who burn biomass for cooking and also providing a readily available source of fuel for them.

If you read through the comments at the bottom of the article you can find a place to link to the plans for his stove as well as an email where you could ask questions.

Polarimetry | yrtemiraloP

Don't panic if you don't get this the first time around. There is time to learn it more carefully, later. But.....

Some of my dear readers were introduced to polarimetry on Friday. A hallway conversation after the lab involved two isomers of the type that can be distinguished by their rotation of plane-polarized light. Both compounds are recognized by us for their tastes. They are the (+) or dextrorotatory isomer called R-carvone and (-) or levorotatory S-Carvone.

Both share the same connectivity and the same molecular formula and while both contain several double bonds, they are not geometric "cis-trans" isomers of one another.

The dextrorotatory isomer is a major substituent in caroway, and is also present in some quantity in dill and in the peel of mandarin oranges. Which I love, by the way. Which are in season, by the way. Get them now because they are seasonable! consider it a chemistry research project.

The levorotatory isomer is a major oil in spearmint. Yep, that's different than caraway or dill, in my book. I have heard however that some people are unable to distinguish between these two substances.

That's a curiosity to me, since the proteins that mediate our chemical senses...smell and taste....are almost always themselves able to clearly distinguish these types of isomers.

These substances are also great examples of terpenes, which I'd love to describe but will have to save for another post.

As always, there is more you can read at Wikipedia.

Tuesday, December 2, 2008

a couple of quick plugs

...for the links I have listed in the upper-right hand corner of this page, under "Stuff I like."

In The Pipeline has been a fascinating read for me, both because it offers up some challenging chemistry and also because it provides great insight into the process of drug discovery. If you're interested, look at it. If you find the articles are difficult, scan through a few and I think you'll learn to appreciate it for that other reason. It's an insider's view of the pharmaceutical industry.

Molecule of the Day is just plain fun, and yields a little inspiration for paying attention to Ochem on any given day.

Sightline is both a news outlet and a link to a blog I like to read, called The Daily Score. The focus is energy and sustainability issues in the Northwest US and SW Canada.

TED is unexplainable. Just check it out and enjoy the streaming video. There's so much there that's good I don't even know where to start.

Science in the News is a daily News roundup that provides me with most of the Science-related stories that make the National News, and many local papers. It's my first source of Science-related news stories.

Go ahead, check them out. Links are right there in front of you, to the right of this post.

spinning vinyl

I have an old turntable in my attic. And I still have my old LP records, including some real classics from the 80s, and at least one especially-expensive high-quality pressed album. It's Pink Floyd's Wish You Were Here. Oh, and I have an EP of Kraftwerk's Tour de France. Great stuff, though I haven't played them for years.

Vinyl records are pressed PVC, or polyvinyl chloride. PVC is a polymer made from a monomer called vinyl chloride, which has the formula CH2CHCl. The alkene polymerizes by an acid-catalyzed addition mechanism to produce long chains. The "vinyl" part of the name is straight from the chemist's lexicon: vinyl means the chlorine is directly connected to the sp2-hybridized carbon.

PVC is manufactured in huge quantities and is the subject of a certain amount of controversy--because of hazards associated with the toxic, carcinogenic monomer it is made from, and also because PVC plastics are often made soft ("plasticized") using phthalates, which sometimes leach from the finished materials and have their own toxicity hazards.

Those of you who are O-chemmers will get the chance to learn more about PVC at the start of Winter term.

Monday, December 1, 2008

Recreational Dimensional Analysis

We did a little math in CH104 this morning.
By our calculation and with some data retrieved from good old Wikipedia, we determined that it would require consuming about 1500 6-oz. glasses of wine per day in order to dose yourself with enough resveratrol to mimic the experiments that showed a benefit in mice.

Which is not to say that lower dosages wouldn't make any difference, or that mice are a perfect model for human nutrition. But it was a fun time, at least for me, and brought home the value of doing a few calculations the chemists' way.