Thursday, November 29, 2007
Wednesday, November 28, 2007
My next Hands-On Learning column for Home Education Magazine will be a crystal-growing project, and there are several versions I want to try. The one we started today comes from The Joy of Chemistry and uses Mrs. Stewart's Bluing. (You can also find the directions, an explanation -- and anything else you ever wanted to know about this old-fashioned, non-toxic laundry product -- on their website.)We combined aspects of both sets of directions. Per JoC, we used an ordinary kitchen sponge, cut into cubes, as the base. But we left out the ammonia they recommend to see if it would work without, since MSB's website said it was helpful but not necessary. The sponge bits were sprinkled with water, salt and bluing.
The PB is insoluble. The Mrs. Stewart's liquid is not a solution, but a colloidal suspension in which very tiny particles of the dye are floating. These small crystallites serve as seeds for the salt crystals that (hopefully) will be growing over the next few days.
Hah! I love it when I sound like I know what I'm talking about!
Tuesday, November 27, 2007
As an introduction to crystal-growing, I thought it would be helpful to talk about solutions. We did two experiments from Chapter 9 of The Joy of Chemistry: precipitating baking soda out of water using table salt (known as "salting out"); and salting out solid soap from liquid dishwashing detergent.
(You will notice that I thought it would OK to skip the hazmat gear for these demonstrations!)
First we made a saturated solution of baking soda in water, by pouring four heaping plastic spoons of the powder (how's that for precision?) into 2 cups of water, stirring, and waiting for the excess to settle out.
Then I "decanted" off the liquid into a cup for each kid, who marked it and filled a second cup with an equal amount of tap water. Equal small amounts of salt were added little by little until a change could be detected.
As with most of the experiments we've done so far from this book, the results were very subtle. The baking soda solution became slightly cloudy when we added salt, as compared to a cup of plain water.
Then we got new cups, put about a quarter inch of dish detergent into the bottom of each and sprinkled it with salt. The directions were incredibly vague: "liquid soap" and "sprinkle" were all they said. Anthony only sprinkled a small amount, but I let John pour it on, just to see what would happen.
In both cups we got a goopy mixture in the liquid. The book referred to this as "solid soap." The kids called it "wet salt." I wasn't sure how to tell the difference. Some ways now come to mind:
- We could have wet some salt with water and noted the difference.
- We could have tried putting another granular substance -- sugar, or sand -- into the soap to see if we ended up with the same kind of gelatinous goop.
Scroll down to see the photos of the kids' experiments. Many of the explanations are clear enough that you could probably recreate them at home.
Saturday, November 24, 2007
That's how much Pierre and Marie Curie were meant for each other.
Like "Young Tom Edison" and "Edison the Man," this 1940s biopic about the life and work of Madame Curieis a little dated in the way it makes its larger-than-life subject seem a little more human. And yet it is sweet and absolutely watchable.
I just opened Eve Curie's biography of her mother, upon which the movie is based, last night. Our library's copy is so old, a school girl's notes for a book report dated 1978 fell out from between the pages. Oliver Sacks tells of giving a speech in which he calls it the best biography he ever read -- then notices an elderly lady in the audience smile in approval. After the lecture, Eve Curie autographed his original copy for him. (Apparently, he carries it with him!)
Some interesting chemical moments in the film include watching the Curies distill tons and tons of pitchblende down, using acids and hundreds of evaporating bowls, until they are left with only a sample of pure radium so small it looks like a stain on the bottom of the bowl. What did they do with all the uranium they discarded? Was the small burn on Marie Curie's palm really the only damage the radioactive material did to the scientists?
I'll have to read the book to find out.
Thursday, November 22, 2007
However, since this nifty volume is out of print, I can't add it to my Amazon list. So go visit Ebay's non-auction cousin, half.com, and pick up a used copy.
Tuesday, November 20, 2007
According to his website, www.scifun.org, University of Wisconsin-Madison chemistry professor Bassam Shakhashiri is "known internationally for his development use demonstrations the teaching of chemistry classrooms well in less formal settings such as convention centers, shopping malls and retirement homes." Shopping malls!
An interesting note: Many of my favorite websites for teaching history to kids belong to elementary or middle school teachers, but so far the best resources for chemistry at home seem to come from college professors. There are also a few good ones for preschoolers and younger kids -- but where are the middle and high school chemistry teachers? Are they all too busy cramming facts into the kids for the SATs?
Monday, November 19, 2007
In addition to reading through The Joy of Chemistry together, I'm thinking of having the kids go through this site on their own. I like the way it explains complex topics in simple language, and I think it might help clarify or reinforce concepts like bonding, stoichiometry and even anti-matter! The pages aren't cluttered, and it's got really nice graphics to explain the concepts in a visual way. And there are online quizzes they can take to see how much they actually absorbed.
No experiments this week --we have a bunch of kids coming over for a birthday party, and I've got to put all the dangerous stuff away. But we should start growing crystals next week, for a Hands-On Learning column I'll be writing for Home Education Magazine.
Friday, November 16, 2007
In keeping with my determination to look at molecules (meaning, for the most part, their graphic representations) with the kids, I've added a new website to the Learn About Chemistry list.
Here's MY molecule of the day: 1,3,7-trimethyl-1H-purine-2,6(3H,7H)-dione, also known as caffeine. I've seen the tee shirt above at my neighborhood coffee emporium. Very cool.
Thursday, November 15, 2007
Went to the Roald Hoffmann talk last night. John (who just turned 15), accompanied me and said he enjoyed it. (It's Hoffmann's wry asides, missing in his video appearances, that make him so engaging in person.) In preparation, we watched the first episode of World of Chemistry online. Then I served two different enantiomers of carvone for lunch: homemade pumpernickel rolls with caraway seeds and spearmint candies. (The rolls came out a little dry; I'll have to find a better recipe.)
In our interview, I had asked Hoffmann what he does to make chemistry more accessible to laymen. He described a typical news item about science, a health story either touting a new miracle drug or decrying the fact that last year's miracle drug has been found to have dangerous side effects. He went on to say
The newspaper will never show a picture of the molecule. They’re deathly afraid to show the molecule. But they will use the name. So when I see that story, I go to Wikipedia and get the structure to show them, and go deeper into the story.So I made sure to show the kids pictures of the right- and left-handed carvone molecules. And I will try to post images of molecules here whenever possible.
Again, if you can get to the Tang Museum to see the Molecules that Matter exhibit do so, if only to get to walk around the giant steel 3D molecular models. As Hoffmann pointed out last night, computer graphics have pretty much made model-building obsolete. But humans are sensory creatures, and the real-life experience is more profound than the most detailed rotating 2D approximation.
Wednesday, November 14, 2007
Although Thomas Edison is known for electrical inventions, there was a lot of messing about with chemicals in this biopic. First he fills the schoolhouse cloakroom with smoke, trying to see if concentrated ammonia and hydrochloric acid mix. (In real life, Edison's mother taught him at home after he was kicked out of school.) Then he stops a train when they find out he's got a bottle of nitroglycerin on him.
It certainly had its hokey side, but the film was touching at times too. And amazingly, most of the unbelievable incidents are actually true. Edison really did start a boyhood business selling newspapers on a train and did chemistry experiments in the boxcar. saved a child on the train tracks and learns Morse Code from the boy's grateful father.
Not a bad little flick, if you're in the right mood. I'm hoping to pick up the sequel, Edison the Man, starring Spencer Tracy, for next week.
Tuesday, November 13, 2007
Lesson: Carbon dioxide is heavier than air
What Happened: CO2 collected in a glass can be poured out so that it extinguishes a candle
Last week a friend who used to teach chemistry at a local community college brought her son over for the afternoon. I had bought some Diet Coke and Mentos for the kids to try outside. My friend's son let my boys take his turn, while he played the role of "brave photojournalist."
I also got my friend to try a demonstration I read about in Uncle Tungsten, and which is mentioned in passing in Joy of Chemistry as an example of the effects of acid rain. It involves dissolving a piece of chalk in a glass of vinegar. My friend and I tried Crayola brand blackboard chalk from Wal-Mart but did not get much of a reaction. Old sidewalk chalk, much thicker and softer, worked a little bit. But for the second half of the demonstration, we had to resort to baking soda.
In Uncle Tungsten, Oliver Sacks describes watching his mother "pour" off the carbon dioxide accumulating in the glass over a candle, which goes out. That's the part of the demonstration I was interested in seeing. A small amount of baking soda and vinegar -- not enough to bubble out of the glass -- did indeed produce enough CO2 to recreate Sacks' childhood memory.
In addition to proving that carbon dioxide is heavier than air, we also demonstrated that even middle-aged moms like to mess around with concoctions. Sometimes more than their kids.
NOTE: Chalk is made of calcium carbonate, a base, the same stuff in limestone and marble. Vinegar is acetic acid. The reason our chalk didn't react very much with the vinegar was that it contained other substances. A little Googling revealed Prang Hygieia, 95% calcium carbonate, as the brand of choice for this demonstration. If I get ahold of some I will give it another go.
Monday, November 12, 2007
And David Brickman has gets a little more humanity into his preview of the same event.
I think I was a little nervous for this interview.
I hestitate to post a link to the World of Chemistry parodies mentioned in the story (I haven't watched them through and don't know how mean they get), but blogger Jennifer Saylor, who watched the series in her junior college chemistry class, has an an interesting take on its appeal:
I’m a huge fan. The videos are utterly dorky, and I find the series irresistible for its awkward charm and nerdiness. If I could get the DVDs from my local video store, I would watch them all.(In the sidebar is a link to a streaming video of the entire series.)
And here's a poem by Hoffmann, that I didn't have room for in the story:
MEN AND MOLECULES
Cantilevered methyl groups,
battered in endless anharmonic motion.
A molecule swims,
dispersing its functionality,
scattering its reactive centers.
Not every collision,
not every punctilious trajectory
by which billiard-ball complexes
arrive at their calculable meeting places
leads to reaction.
Most encounters end in
a harmless sideways swipe.
An exchange of momentum,
a mere deflection.
And so it is for us.
The hard knock must be just right.
The eyes need lock, and
glimmers of intent penetrate.
The setting counts.
A soft brush of mohair
or touch of hand.
A perfumed breeze.
Men (and women) are not
as different from molecules
as they think.
Thursday, November 8, 2007
During World War II, the Japanese blocked the US from importing rubber. The government asked the chemical industry to find a substitute. James Wright, an engineer working for General Electric, created a polymer from silicone and boric acid. Dr. Joe Schwarcz describes what happened next in his book The Genie in the Bottle:
The pliable mass could be rolled up into a ball and bounced 25 percent better than a comparable rubber ball. Here was the desired property. Unfortunately, the substance had some undesirable properties as well. When you hit it with a hammer, the stuff shattered; when you pulled it quickly, it broke apart. A fascinating but useless substance.GE sent samples to engineers around the world, hoping to find a suitable application. Then, in 1949, some of the putty fell into the hands of toy shop owner Ruth Fallgatter. Although it outsold everything in her shop's catalogue (except for Crayola crayons), Fallgatter lost interest. But the marketing consultant she hired, Peter Hodgson, repackaged the gooey slime in plastic eggs and Silly Putty was born.
Yesterday I took the kids to the Schenectady Museum for the second in a series of science workshops for local homeschoolers. (Schenectady, of course, was once GE's "Electric City," and the museum is home to lots of GE memorabilia and Edison artifacts.) This month's topic was chemistry, and one of the hands-on projects the kids got to do was to make a version of Silly Putty from Borax (a type of laundry soap) and Elmer's glue. This is a standard little-kid chemistry demo; there were three booths featuring it at last month's New York State Museum Chemistry Week event. (Here is about.com's recipe.) Unfortunately, given the current trend away from experiments involving any degree of risk, it also seems to have become a standard big-kid chemistry demo as well.
The homeschool workshop description talked about having the kids make several types of putty and recording their observations (how high they bounced, etc.) I thought maybe they would be using different formulas. (For instance, there are a variety of recipes here.) What they did was give the kids was different concentrations of borax and glue. John came home with a bag of goo; Anthony didn't have time to finish all three versions, so he didn't end up with a playable mixture. We'll have to do this again at home.
Considering that this program was for kids up to age 14, it would have been nice if they included a few more facts, too. Such as the chemical names and formulas of the different substances the kids used. So here is a look at Borax (sodium borate - Na2B4O7) and the Elmer's Glue ingredient polyvinyl acetate, courtesy of Wikipedia.
(There's more to it, of course, but the full explanation I found from Newton Ask a Scientist is beyond me.)
NOTE: Real Silly Putty is made from boric acid and silicone, both easily-obtainable substances. However, I've seen the reaction to combine them described as "violent," so perhaps it's best to stick with Elmer's and 20-Mule Team -- at least at home!
Tuesday, November 6, 2007
Hoffmann's book The Same and Not the Same touches on many of the topics he will be talking about next week. Did you know that there are right-handed and left-handed molecules? There's a little tidbit on page 42 about the relationship between caraway seeds and spearmint that the kids might appreciate.
Friday, November 2, 2007
If you've ever learned a new word you'd never seen before and then had it pop up 12 more times in the next week, you'll understand how this chemistry immersion course is affecting me. As the chemists I've been talking to keep pointing out, chemistry is everywhere, and everything is turning into a teachable chemistry moment.
So when my doctor sent me for tests to see if my thyroid was acting a little sluggish and the technician handed me a capsule containing 200 microcuries of I-123 and told me to come back in 6 hours, my first response was, "Can I bring my camera?"
Testing for thyroid function involves swallowing a radioactive isotope of iodine, which naturally collects in the gland, so that a nuclear camera can detect how much of the chemical is being absorbed and create an image.
The capsule itself came in a hard plastic case that reminded me of the puzzle tube from The DaVinci Code. Inside was a test tube inside another test tube, and then the pill itself, which looked like ordinary cold medicine.
When I returned to the hospital in the afternoon, the first thing they did was compare the radioactivity of my neck, where the thyroid is located, with that of my knee. (They use the knee because it's about the same size around as the neck.)
Then I was placed -- a little awkwardly, as you can see -- under a big nosecone that was positioned above my neck.
One tech put a thin radioactive bar across my thyroid for the machine to focus on. Then I just lay there for five minutes.
The photos taken by the other tech shows the image appearing on the machine's screen.Iodine 123 is an isotope of regular Iodine, atomic number 53, the stuff they put on cuts when I was a kid. It emits gamma rays, but its half life is only 13.13 hours. The only caution I was given was to avoid eating fish, since it might add to the iodine in my system. The techs handled the capsule without any special shielding.
By contrast, when a friend of mine was given Iodine 131 about 15 years ago to destroy her overactive thyroid, she says the tech was covered in a lead apron and wore a big welders-type mask and gloves. The capsule was stored in a big case, removed with tongs, and dropped into a paper cup for her to swallow. She had to leave her house for a week to avoid contaminating her then year-old daughter.
Thanks to the nuclear medicine techs for answering my questions and allowing me to bring my camera into the room -- and for inviting me to bring the kids. (They didn't come though; couldn't convince them to get up so early!)