Make: Online: Chemistry Archives

Archive: Chemistry

November 20, 2009

Make: Projects - Pneumatic trough, part II

image from golden book of chemistry experiments page 28.jpg

Last week I wrote about how to construct a simple sheet metal "bridge," which, in combination with an ice cube bucket and an olive jar, makes an effective pneumatic trough for collecting gas samples over water. This week I'm going to show you how to use this apparatus to generate and collect pure oxygen, and how to use that oxygen to observe the brilliant blue flame of sulfur oxidation.

Tools:

Pneumatic trough apparatus from part I
Small piece of plate glass (I used the mirror from a makeup compact)
Lighter
Twisted wire sample loop
250 mL Erlenmeyer flask (I got mine from The Maker Shed)
#7 two-hole rubber stopper to fit Erlenmeyer (mine came from this assortment)
Two 80 mm lengths of 5 mm glass tubing to fit stopper (such as this)
Approximately 18" length of 5/16" OD x 3/16" ID PVC tubing to fit glass tubing (common hardware store item)

Materials:

Water to fill bucket
Elemental sulfur powder (also called "Flowers of Sulfur," available at some drugstores and here.)
3% hydrogen peroxide (common drugstore item)
Manganese dioxide (can be recovered from an alkaline dry-cell battery or purchased here)
Petroleum jelly (drugstore)

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November 19, 2009

Make: Holiday Gift Guide 2009: Science and Chemistry

Those of you who know me will know I'm slightly biased toward chemistry, the discipline in which I'm trained, so it's hard for me to resist the natural temptation to focus on gifts that I might like for myself. So, if you astronomers, physicists, biologists, geologists, mathematicians, ecologists, computer scientists (and anybody else I may have accidentally left out) have suggestions for those in your own disciplines, please feel free to submit them in the comments! Chemists, too, of course!

Molar beach ball ($7.50 from the American Chemical Society)
A "mole," in case you don't know, is the unit used by chemists to enumerate atoms or molecules. One mole is Avogadro's number (6.02 x 10²³) of individual atoms or molecules. One of the remarkable things a person learns in general chemistry is the huge difference in molar volumes between liquid and gas phases. A mole of liquid water, for instance, takes up 18 mL, whereas the same number of water molecules in the gas phase takes up 22400 mL! Another interesting fact is that, because molecules interact so little with each other in the gas phase, all gases have effectively the same molar volume, which, again, is 22400 mL, or 22.4 L, at average atmospheric temperatures and pressures. The American Chemical Society has designed this cool beach ball to contain 22.4 L, or one mole, of gas. It's a great teaching aid and a nifty idea in general.

Borosilicate coffee cup ($9.99 from ThinkGeek)
Part of the experience of becoming a chemist is learning to appreciate glass. Glass is totally ubiquitous in our world, but only after working with it under the relatively extreme conditions of the lab does one really begin to appreciate how truly amazing its properties are. Worked with relative ease, resistant to almost all chemicals, capable of enduring extremes of temperature and pressure, and to top it all off, transparent so you can see what's going on, borosilicate glass is surely one of the greatest achievements of materials science. Besides these reasons, chemists and other scientists tend to run on coffee (I've even gone so far as to suggest that coffee causes scientific thinking, to some extent), and at ten bucks, you'd be hard pressed to find a more cost-effective gift for one than this borosilicate coffee mug from ThinkGeek.

Water aspirator ($19.90 from Science Kit)
Every hobby chemist wants a vacuum pump, but many of us can't afford one, either in terms of absolute cost or in terms of available space. Fortunately, there's a wonderful low-tech way to generate a low vacuum, suitable for filtration and many distillations, using an ordinary sink and this inexpensive bit of kit called an "aspirator." The aspirator exploits the Venturi effect (Wikipedia) to generate negative air pressure at the sidearm from the flow of water out the bottom. And while it may look like the sort of thing you could build yourself from hardware store bits and pieces, in point of fact the hydrodynamics of a good aspirator are fairly complicated and it makes much more sense to just buy one. You may have to buy an adapter to make it fit your particular sink, but these can almost always be found at the corner hardware store for a couple of extra bucks.

Theo Gray's Mad Science ($24.95 from The Maker Shed)
I reviewed Theo Gray's newest book for MAKE, Volume 19, and had this to say about it:

If you've ever thrilled to a chemistry demonstration, Mad Science will bring you great joy. If, like me, you've ever wiled away an evening (or eight) figuring out just how hard it would really be to construct your own 3 MeV linear accelerator for making Lichtenberg figures, you may be unable to put it down. My review copy is dog-eared at nearly half of the fifty chemical wonders included: Investigate this. Build that. Would it be possible to...?. In the week since I got it, I've already been to the shop more than once to fan some spark that struck while leafing through its pages.

The book has beautiful photos of those experiments that are too dangerous for most of us to try on our own, and plenty of safer fare for those who want to play along at home.

illustrated guide to home chemistry experiments.jpg

Robert Bruce Thompson's Illustrated Guide to Home Chemistry Experiments ($29.99 from The Maker Shed)
Illustrated Guide to Home Chemistry Experiments is absolutely the best guide to hobby chemistry that I have ever encountered. In 22 chapters across 413 pages, Bob takes his readers through the basics of keeping a notebook and safely storing chemicals to the subtleties of organic synthesis and forensic analysis, and all with a ferociously independent, hands on, less-is-more DIY style. I really love this book.

1000 mL separatory funnel ($39.95 from The Science Company)
The dedicated amateur or hobby chemist can achieve amazing things using old jelly jars and coffee pots, but there are several pieces of "professional" laboratory glass that are difficult to improvise from common materials, and the most useful of these is probably the separatory funnel. A good sep funnel, with a teflon stopcock and a ground-glass joint and stopper, is essential to perform the liquid-liquid extractions that are a routine part of even the most basic isolations and syntheses. And you can almost never have too many. This 1000 mL version from The Science Company is large enough for nearly any purpose. A ring stand and 4" support ring to hold it in place makes a nice afterthought.

Distilling apparatus ($49.95 from The Maker Shed)
The Maker Shed offers this really beautiful borosilicate glass distillation kit, including a 1000 mL sidearm flask with stopper and a 200 mm spiral "Graham" condenser, all at the truly astounding price of $49.95. All the joints are easily demountable gas/liquid-tight ground glass, so there's no monkeying around with rubber stoppers or bits of glass or rubber tubing to make the connections. Distillation is used for separating mixtures of liquids having different boiling points, and the most common use, of course, is in making liquors like whiskey or brandy from beer, wine, or mash. Again, you might want to throw in a couple of ring stands and utility clamps.

Electronic tabletop balance ($117.00 from The Maker Shed)
A good balance is a totally indispensable tool for quantitative chemistry of almost any type. The important figures of merit for a balance, in rough order from most to least vital, are resolution (the number of zeroes after the decimal point), capacity (the maximum upper mass limit), precision (the consistency of repeated measurements of the same mass), accuracy (how close it reads to the "true" value, which is easily corrected by calibration), and linearity (how well precision and accuracy are maintained across the balance's mass capacity). The better each of these figures, the more the balance will cost. Professional "analytical" balances, capable of weighing to a milligram (0.001 g) or less, cost thousands of dollars and include an enclosed glass cabinet over the weighing pan to prevent interference from air currents, which they are sensitive enough to detect. Hobby chemists generally have to compromise, but good centigram (0.01 g) balances are quite accessible and are adequate for most purposes. This My-Weigh iBalance 201 digital balance from The Maker Shed has centigram resolution and a capacity of 200 g, and was recommended to us by Robert Bruce Thompson, author of our Illustrated Guide to Home Chemistry Experiments.

Laboratory hotplate / stirrer ($149.95 from The Maker Shed)
After using a stirring hotplate for awhile, you'll start to get annoyed that your kitchen stove doesn't include a magnetic stirrer. And for $150 new, you'd be hard-pressed to beat this combination unit from The Maker Shed, which includes a built-in ring stand support, rod, and thermometer clamp. Don't forget a couple of teflon stir bars to actually do the stirring.

For many more chemistry and science-related gift ideas, check out the Science Room in the Maker Shed.

The Maker Shed has all sorts of other great holiday gift ideas, Arduino & Arduino accessories, electronic kits, science kits, smart stuff for kids, back issues of MAKE & CRAFT, box sets, books, robots, kits from Japan and more.

Holiday Shipping Deadlines in December:

04 (Fri) - Deadline for microscope shipping
11 (Fri) - postal shipping deadline
14 (Mon) - ground shipping deadline
18 (Fri) - FedEx 3-day shipping deadline
21 (Mon) - FedEx 2-day shipping deadline
22 (Tue) - FedEx overnight shipping deadline

*Customers experiences on orders with these ship methods placed after these dates may vary, the dates listed are what we call "safe dates"

USPS (Any Method):
Due to the high volume of mail that the postal service deals with around the holidays, order by Dec. 10th, however, many packages are lost or delayed in transit and we do not replace or refund any orders lost using this ship method, we strongly encourage you to not use this method in December.

November 18, 2009

Electroluminescent liquor labels

Among the hairier of my hare-brained schemes involves formulating a safe-to-drink chemiluminescent cocktail. I think the first person to do it will become a very wealthy laughingstock, which, as I understand it, is the very definition of The American Dream.

So I got really excited when I first saw this post over on TheDieline.com, because I thought somebody had pulled it off. Unfortunately, it's just the labels that are glowing, not the booze itself, but still it's pretty cool. If you ignore the crass commercialism, the shameless marketing, the horrors of alcoholism, drunk driving, etc., etc. [via Geekologie]

How to make your own caffeinated alcohol beverage

If San Francisco City Attorney Dennis Herrera gets his way a generation of club goers will miss out on the sickly sweet tang of caffeinated alcohol beverages like Sparks, Four-Loko, and Joose. Yet, all is not lost. A group of enterprising practitioners have seized the opportunity to handcraft a batch of Bathtub Sparks in an attempt to recreate the extreme libation.

The following drink was reverse-engineered from a vintage can of caffeinated Sparks and rigorously tested via blind taste-test by SFoodie and four people who agreed to come over to the author's house and drink this stuff, plus two random guys on the street who should be applauded for their daring and general zest for life.

HOW TO make Moonshine Whiskey

Garbage bag + rice cooker = alcohol still

Home Distillation of Alcohol

November 17, 2009

Color thermal inkless printing technology

My father recently drew my attention to an article in IEEE Spectrum about the so-called "Zink" printing technology commercialized by a group of former Polaroid employees. Zink, an acronym for "zero ink," uses special paper with three layers of embedded dye crystals activated by heaters in the print head. Solely by controlling the temperature and duration of heat pulses delivered by the print head, the yellow, magenta, and/or cyan layers may be selectively activated. It is essentially a refinement of the black-only thermal printing technology commonly used, for example, in cash registers and label makers. By eliminating the requirement for ink or toner, Zink promises to produce dramatically smaller and more portable color printers, and has already been incorporated in several "digital polaroid" style cameras with integral photo-printers, such as the Polaroid PoGo Instant Digital Camera. [Thanks, Dad!]

November 13, 2009

Make: Projects - Pneumatic trough, part I

Although it sounds like some kind of euphemism from Brave New World, a "pneumatic trough" is actually a very handy piece of classic chemistry lab kit. Besides providing a convenient means to collect samples of pure gases for various experiments, a pneumatic trough with a graduated container allows the easy volumetric measurement of reaction yields for gas-producing reactions.

If that all sounds too complicated, don't sweat. What I'm going to show in this tutorial is simply how to build a simple piece of apparatus that allows you to collect pure gas samples over water. You can collect carbon dioxide, oxygen, hydrogen--almost any gas you can generate and direct down a hose.

It seems like a simple enough bit of equipment: all you need is an upside down container suspended in a bucket of water. Finding a convenient way to set that up, however, is tougher than it sounds. The pneumatic trough presented here, which uses a sheet metal "bridge" to secure the glass column, is by far the most painless and economical way to make it work that I have found. The basic idea is derived from illustrations in Robert Brent's 1960 Golden Book of Chemistry Experiments (from which the title diagram is taken), but the addition of an aperture shaped to accept the threads of a glass jar is of my own devising.

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November 12, 2009

Temperature regulating coffee mug

Klaus Sedlbauer and Herbert Sinnesbichler, of Germany's Fraunhofer Institute for Building Physics (IBP), think coffee is perfect at 58 degrees C. So they built a coffee mug that automatically maintains that temperature, tending to cool its contents above 58 degrees, and releasing heat below 58 degrees to warm them back up. It works by use of an interstitial phase change material (PCM, Wikipedia) between the aluminum fins, which has a solid-liquid phase change temperature of 58 degrees. Above 58 degrees, the PCM melts and absorbs heat, and below 58 degrees it freezes and releases heat. Supposedly it can keep a cup of coffee at ideal temperature for 20 to 30 minutes.

November 11, 2009

Charcoal foundry build at Chicago hackerspace

charcoal_foundry_glowing_purple (Custom).jpg

Tim Saylor recently wrote in to me about the Gingery-style charcoal foundry he built for Chicago's hackerspace Pumping Station: One. There's a write-up here and a good Flickr set showing construction and use of the furnace to melt aluminum here, including some really pretty shots of the fire and sparks at night. [Thanks, Tim!]

November 10, 2009

Layer-additive "welding" 3D fabrication

Electron Beam Free-Form Fabrication (EBF3) is a rapid prototyping technology developed by Karen Taminger of NASA's Langley Research Center. Dr. Taminger is prone to market EBF3 by analogy to Star Trek style "replicator" technology, which is nothing but shameless hype. Still, the basic idea is an interesting twist on extrusion-based 3D printing technologies (although there's not really any "extrusion" going on), and is under development with an eye towards space-based fabrication. Working in outer space would eliminate the system's major ground-based shortcoming, which is the requirement for maintaining a vacuum or inert atmosphere to prevent oxidation of the weld.

November 3, 2009

Functioning X-men "Pyro" costume flamethrower appliance

OK, my awesome meter has kind of overloaded on this one. Everett Bradford's "Prometheus Device" is a hand-mounted appliance that shoots, like, real fire. It looks, you know, dangerous, and all, but it's so cool I don't really care. And he's done a great job documenting the build, although obviously no one should attempt this who doesn't know what they're doing. Amazing work, Everett. Thanks!

Make: Halloween Contest 2009

There's still time left to enter the Make: Halloween Contest 2009! Deadline is 11:59 PM PST, November 3rd. Show us your embedded microcontroller Halloween projects and you could be chosen as a winner.

October 31, 2009

Pumpkin abuse in the name of science

Over at the Periodic Table of Videos, their chemists put pumpkins through the ringer to demonstrate properties of various chemicals, states, and processes. Nice to see Halloween getting the whole "Peeps in the microwave" treatment. [Thanks, Shawn!]

Periodic Table of Videos

More:
See our own growing collection of chemistry experiments in the Make: Science Room

October 30, 2009

Periodic taxi

Follow up - Bruce sent this in "Periodic taxi"!

Periodic table

Ptable
A maker sent this in, nice table!

October 29, 2009

Flammable ice

This awesome little chemical machine is from Mr. Kent's chemistry page. Ice is laid in a Pyrex dish over a layer of calcium carbide. As the ice melts, the liquid water reacts with the carbide to produce acetylene gas, which of course is highly flammable. A match starts it off, and then it burns continuously on its own. My first thought was that the system could rapidly spiral out of control--more heat melts more water makes more gas makes even more heat. But it's limited by the amount of oxygen that can get down into the pan, I think. My second thought was that maybe a bit of sodium metal down there with the carbide could make the process self-igniting.... (For God's sake, no one try that.)

Lots of great new Science Room content

We've got lots of new content in the Make: Science Room, including a whole new Forensics series on the many methods of fingerprinting. Tired of those bitter family disputes over who ate the last ice cream sandwich? Take the wrapper to the lab and find out for sure!

We also have a lab on testing for lead paint and an introduction and series of labs on colloids and suspensions. What in blue-blazes is a colloid, you ask? Why it's a "two-phase heterogeneous mixture made up of a dispersed phase of tiny particles that are distributed evenly within a continuous phase." Think: homogenized milk. It has tiny particles of liquid butterfat (the dispersed part) suspended in water (the continuous part). That's a colloid.

And then there are sols, that's a "solid phase dispersed in a liquid continuous phase. Ordinarily, a sol is a liquid, but it can be converted to a semi-solid gel by adding a gelling agent. In some cases, the solid phase itself may also serve as the gelling agent."

An example of a gelled sol is the notorious Super Napalm B. And guess what? We show you how to make it -- just in time for Halloween. We're kidding. KIDDING! This is serious stuff, a cool experiment, but one with real dangers. This is seriously volatile burning material that's also a seriously sticky gel, a deadly combination (hence the notoriety).

Here's the door to the Science Room >>

In the Maker Shed

And don't forget all of the awesome science-related products now carried in the Maker Shed, including a Latent Finger Printing Kit and a Lead Paint Test Kit (seen above).

October 28, 2009

Interesting cancer resistance in naked mole rats

There's a ridiculous amount of hype in science today, and in an area as sexy as cancer research it is perhaps even worse. In writing this post, I am mindful of the "sharks don't get cancer" trope that's been used irresponsibly to sell shark cartilage as snake oil, very often to people who are in a desperate situation. Consider that a disclaimer.

There is, reportedly, a very low incidence of cancerous tumors in naked mole rats. Statements like "there has never been a tumor found in a naked mole rat" may be misleading unless they also explain to us just who is looking for tumors in naked mole rats, how long they've been doing so, how hard they're looking, who's paying for it, and why. Still, I think this paragraph is interesting:

The findings, presented in today's issue of the Proceedings of the National Academy of Sciences, show that the mole rat's cells express a gene called p16 that makes the cells "claustrophobic," stopping the cells' proliferation when too many of them crowd together, cutting off runaway growth before it can start. The effect of p16 is so pronounced that when researchers mutated the cells to induce a tumor, the cells' growth barely changed, whereas regular mouse cells became fully cancerous.

Of course, there's all kinds of reasons why it might work for naked mole rats and not for people, but the idea that a mechanism as simple as cellular "claustrophobia" might go so far to eliminating tumors is pretty interesting. Here's the original abstract at PNAS.

October 27, 2009

Super cements aka "geopolymers"

Think cement is just cement? Not so. These unlovely mugs are nonetheless very special. Prepared from special synthetic aluminosilicate materials called "geopolymers" (Wikipedia) by members of Dr. Waltraud M. Kriven's research group at The University of Illinois Urbana-Champaign, these mugs were tested in a special "mug drop" event at the 2004 American Ceramic Society (ACeRS) conference, and supposedly "were impossible to break at even 50ft onto bare concrete" (although the photos clearly show an astroturf-covered floor). Danger Room's David Hambling recently posted a nice overview of geopolymer technology with an eye towards defense applications. These presentation slides by Dr. Kriven (.pdf) include some actual formulae.

October 26, 2009

Bob Thompson on laboratory scales

Bob Thompson, our resident Make: Science Room lab geek, answered a question in the comments for the "Setting Up a Home Science Laboratory Part II - Gearing Up" topic, about buying digital scales. I thought it was worth posting here for the benefit of others.

Cynthia asked:
What would you recommend in the way of a digital scale for intermediate/high school science? I was thinking of purchasing one that was a 1000 g capacity with a 0.1 sensitivity. Could this both serve chemistry and physics, etc.?

Bob's reply:
Good question. The two big trade-offs in buying a balance are capacity and resolution. Ideally, we'd all like an inexpensive balance with 0.0001 gram resolution, but unfortunately, there aren't any such animals.

The balance I chose two or three years ago for my own home lab is the desktop MyWeigh iBalance 201, which has 200 gram capacity and 0.01 gram (centigram) resolution. That's still a current model, and is available in Maker Shed and elsewhere. However, it's also a $100+ balance.

If you're looking for something a bit less pricey, Maker Shed also carries a portable $33 electronic balance (on sale through 10/31 for $29) that has the same 200 gram capacity and 0.01 gram resolution. I have one of those as well, and it's a very nice little scale. I suspect it probably isn't quite as durable as the i201, but OTOH, it's less than a third the price. (It's also useful around the house. My wife just used it yesterday to see if she needed to put a second stamp on an envelope.)

My take on this is that 200 g is sufficient capacity. Almost any experiment you do that would use the 1000 g capacity of the balance you're considering can be scaled down to work within the 200 g capacity of these balances. OTOH, having 0.01 g resolution instead of 0.1 g resolution is very nice, particularly for chemistry.

It'll also save you money on chemicals. For example, if you need to make up a solution to a particular accuracy, being able to weigh out (say) 7.87 g of the chemical and making up 100 mL of solution is cheaper than having to weigh out 78.7 g of the chemical and make up 1,000 mL of the solution.

This way to the Make: Science Room >>

October 23, 2009

How-To: Make chemiluminescent soap bubbles

No photos yet. That's a homework assignment for the bubble chemists in the audience. But I couldn't resist sharing my excitement over this paragraph from US patent 5,246,631 for glowing soap bubbles:

An example of practice of the present invention involves using a liquid dish such as LEMON JOY available from Procter & Gamble Company (Cincinnati, Ohio). Although the LEMON JOY may be diluted with varying amounts of water, it is preferred that the dishwashing liquid be used at full strength. Approximately 9 milliliters of CYALUME solution made in accordance with the manufacturers instructions are added to approximately 120 milliliters of the dishwashing liquid. Although this particular mixture may be used to produce adequate self-illuminated bubbles, it is preferred that 3 to 4 drops of glycerin be added to the solution as a bubble hardener. The solution is then ready for use to form self-illuminated bubbles.

I've never actually measured how much Cyalume (Wikipedia) is in a standard glow-stick, but I'm betting you could come up with 9 mL of the stuff by cutting open two or three at most.

October 21, 2009

"The joy of sex don't last like the fun of shootin' anvils"

To "shoot," an anvil, for the record, is to blast it several hundred feet into the air using a charge of black powder. This delightful man, Gay Wilkinson, is apparently the world's champion anvil-shooter. The fireworks start at 1:30. [via Boing Boing]