Slashdot Mirror
World's Most Exciting Chemistry Movies
Michael Buckbee writes: "After Dan's page got too slashdotted to view, I ran a quick search on Google for more more fun Ferroliquid sites and stumbled into a collection of movies that I wish had been taken in my chemistry classes. Almost all of the experiment descriptions lean heavily on the phrase "EXTREME DANGER" and many contain other fun words like: "Explosion", "Toxic", "Detonation", and "Diazotization"."
>Almost all of the experiment descriptions lean heavily on
>the phrase "EXTREME DANGER" and many contain other fun
>words like: "Explosion", "Toxic", "Detonation", and "Diazotization"."
Sounds like MSNBC's coverage for the past week...
Here's a short depiction of what I'm trying to accomplish. If you've got any ideas - pass them my way...I've got a balloon of ferrofluid suspended inside a tube filled with the water - attached to the walls. Outside the tube I have a configuration of solenoids, hooked up to deliver a magnetic field in sequence starting at one end of the tube - and stepping to the other end. The effect should expand the balloon to the walls of the tube, and the stepping of this bubble down the tube should propell the water... Hopefully in a smooth fashion. I've got everything working except the sequencing drivers for the solenoids, so it's looking good so far.
I never got around to trying to build an MHD fountain that would shoot salt water up in the air past a large magnet and a pair of electrodes. Has anyone tried this kind of a project?
Well You could have knocked me down with a feather.
Na Cl
Need a light, Salted
"Sorta like the 'light my fart' pictures that those morons in high school were always trying to take."
"Blue flames abound, but we were always puzzled by the one guy who produced green flames. Never did figure out how."[emphasis added]
Interesting how "those morons" in the first sentence becomes "we" in the second. I guess that's what happens when one puts people down for doing something one does themselves. 8^}
Cheers,
Zero__Kelvin
Guns don't kill people; Physics kills people! - John Lithgow as Dick Solomon on Third Rock From The Sun
Our HS chem teacher was nice/crazy enough to allow us to do any experiment we wanted as long as it wasnt too dangerous. So I ended up doing the Nitrogen Triiodide experiment. I think I made too much cause we went without using one of the fume hoods for a month. Everyone was too scared to go near the filterpapers because they would spontaneously react. It was fun watching the lower divistion classes jump when some would spark drung a lecture.
How about "World's Most Slashdotted Chemistry Movies" ?
This is the place where you write something that will make you seem like a complete idiot.
It should be quite easy to use mod_rewrite in apache to set it up to respond to all requests where the referer contains "slashdot.org" with a '404 slashdotted' response. Perhaps such a configuration it should come as part of the default apache config ;).
MTV Press Release: Following in the footsteps of the controversial show "Jackass," MTV proudly presents a similar show for those of the chemical persuasion: "Jackass Chemistry." Tune in each week to see your favorite nerds mix things that should not be mixed together. Watch the halarious explosions and poisonous gas clouds that follow! For mature audiences only. WIK
I never got around to trying to build an MHD fountain that would shoot salt water up in the air past a large magnet and a pair of electrodes. Has anyone tried this kind of a project?
:).
I tried building a railgun once, which worked on exactly the same principles (run current through a metal projectile perpendicular to a magnetic field).
My projectile was a shred of tinfoil. It twitched, but didn't move. Then I did the calculations to find out exactly how much current I'd need for a decent amount of force on the projectile.
Even with a very strong magnetic field (think "one tesla"), you're going to need a silly amount of current to apply enough force to give a nice fountain effect (think "hundreds of amps"). This will heat your water up quite a bit, and give you quite a lot of hydrogen and chlorine gas as a byproduct if you're using saltwater.
It should still be do-able; I'm just warning you that it won't be as easy as you might hope
Use a nitrate as the electrolyte and you'll avoid the chlorine gas problem (you should get hydrogen and oxygen).
Maybe more people would study chemesty if they followed the example of Britney's Guide to Semiconductor Physics.
Dude, F=BLI. There's no squaring at work here. You'll need 100's, if not K and M amps to do anything resembling a railgun.
:).
But, P=I^2R. Your Joule heating will be considerable. You'll need some good engineering so that your toy won't disintegrate itself.
And V=LdI/dT. You'll need city bus size capacitors and hydrogen thyratrons to switch massive currents quickly. For railguns we're talking mega-amps in 20 nanoseconds.
Depends on what you call a "railgun".
If you're trying to make a small water fountain, you can get away with a newton of force or less. You'd also be working in continuous mode, which means a capacitor bank isn't needed (just a DC or approximately DC power supply that can provide the needed current).
One-tesla magnets are easy to buy or build - about one tesla is the saturation point of most ferromagnetic materials, so a chunk of iron will turn a 0.01-T or 0.001-T solenoid into a 1T magnet in short order (depending on the permeability of garden-variety scrap iron).
Similarly, high-strength permanent magnets will be in the Tesla range (probably more like half a tesla, but still strong enough for our purposes).
At one tesla, for a force of 1N, and assuming a water tube 1 cm wide, a current of 100 amps is adequate. A step-down transformer, a bridge rectifier, and a wall plug, and you're there.
For a proof-of-concept tabletop railgun, you can similarly relax constraints. If I'm trying to fling, say, a 10g segment of copper plumbing pipe across a room, I don't need a capacitor bank - I need a marine battery. If I can fire the projectile at 10m/s, that gives me a good 5m or so before it hits the floor from tabletop height (10m if I fire it at an angle instead of level); more than enough for a party trick. At that low a speed, it's in the railgun for tens of milliseconds or longer - I don't need nanosecond discharge circuitry. My hypothetical 10g projectile would have a kinetic energy of about half a joule, which means that if my railgun is about a foot and a half long, I again need only 1N of force. A marine battery can supply the required 100 amps of current without any problems at all (in fact, I'd want to drop a resistor in series with it to make sure it doesn't supply much more than that when I short the railgun across it).
Preventing the slug from spot-welding itself to the rails is left as an exercise for the reader
In summary, while I'd need heftier electronics to build a military-grade weapon, tabletop railguns and similar motor-principle conversation pieces aren't that hard to build.
[Aside: I'd actually build a coilgun instead of a railgun if I wanted a military-grade weapon. Much, much easier to build at high power than an ultra-high-current railgun (it's just a series of high-power RF or IF coils repelling the slug with induced currents). Even here, millisecond-level timing is perfectly adequate.]
In reading some of the comments here, I get the disturbing feeling that what most of us learned in science classes was "How to blow stuff up real good!"
I never had any chemistry classes, but I don't think a day went by in our electronics class when someone did not catch something on fire. My favorite was the day we hooked a 2N2222 randomly up to 120v and watched it light up. Since it only lasted a few milliseconds we decided to liquid cool the sucker.
So, we wired one up, put heat shrink tubing around it, dunked it in a glass of water, and let the current flow. That dude lasted about 25 seconds before all the smoke was let out.
But nothing beats the day I was at my friend Tom's. We were in his lab in his basement and were just goofing around with something on an o-scope. He was rummaging around in the closet for something and ran across some great big 1000V capacitors that came out of some HV power supply. These things were huge. Tom slapped it down on the desk, hooked it up to a power supply, and proceeded to charge it up. I was talking to someone on Tom's 2m ham rig and was watching out of the corner of my eye as he started to throw stuff across the terminals. An aluminum can got two big holes blown in it. a paperclip blew in half. Needless to say what he was doing was causing loads of interferance and I could only get a few words of what I was listening to. I asked the other station to repeat.
Then the interferance really started - though it was not due to the spark gap transmitter that was just a few feet away. It was because of me laughing. Tom got the idea to drop a piece of aluminum foil across the cap and it stuck to the terminals. He reached down to pull the tin foil off and burned his hand, yelled "damn! that's hot!" then picked up the cap and tossed it back in the closet. I was laughing so hard I had to sign off cause I could not talk for about 5 minutes.
How I wish that had been a Kodak Moment.