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Surprising Science Demonstrations?
An anonymous reader writes: "I have been called upon to conduct some science workshops for children of various ages, and I'm looking for some good demos. In particular, I've found that demos are most effective at getting students to think when they give a surprising or unexpected result, such as the classic two-slit experiment (or, for the extreme crowd, demonstrating the Leidenfrost effect by sticking one's hand into a vat of molten lead [PDF]). I'd like the Slashdot crowd's suggestions." Please don't do the lead one.
Put some sugar (white cane) 1/4 full into a test tube. Pour on sulphuric acid to 1/2 full. Wait for a 1-2 minutes and watch the carbon rod emerge from the test tube amidst smoke!
It's funny to watch.
this worked before in a chemistry demo i gave in high school. It gives an unexpected result and it is colorful to boot :-) http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA2/MAIN /AMFOUNT1/CD2R1.HTM for more details
put a little wax in a foil dish, heat it over an Bunsen burner, then squirt water at it... HUGE fireball... People don't think it will happen, but it does, it also seems to be safer than oil
Another one my chem teacher did was taking water and separating it into oxygen and hydrogen by using a battery and matching the terminals, then letting the hydrogen into a test tube and light it to make a loud "pop!"
Also, anything that disolves metal with a liquid is good, like magnesium and acid or such.
1: Using compressed air to shoot a pencil through a peice off 1/2 inch thick plywood
2: Using a large solenoid to magnetically rip apart an aluminum can (can is placed in the center of the circle of wires and large AC is momentarily applied)
3: Pouring liquid nitrogen on your hand (the back, not your cupped hand)
4: Making liquid nitrogen ice cream (pour some LN2 into a cup of milk, stir rapidly)
5 Superconducting magnetic levitation (small permanent magnet over a critically cooled superconductor)
6:The ever classic fire extinguisher used to propel a person across a room in a rolling chair
7: compairing the explosions made by a baloon filled with air and h2, h2, and one with both H2 and O2 in proper amounts
The University of Wisconsin has a site at http://genchem.chem.wisc.edu/demonstrations/ that contains links to dozens of demos (with raitings) for various categories. I'm sure there is something for each age/interest level there
Get a petri dish, a plate magnet, a superconductor, and some liquid nitrogen. Put the petri dish on top of the plate magnet, and the superconductor inside the petri dish. Slowly pour in the liquid nitrogen. When the superconductor reaches superconductivity, it'll float.
(or do something along those lines...)
~A'Ëq'i4d)^'$ÊSÈòB
I would suggest the use of a microwave oven and a variety of things, my favorites are:
1: Lightbulb, metal in milk to insulate, don't use anything with mercury in it.
2: CD-Rom (all kinds work, try different ones)
3: place a toothpick in a peice of cork, place in center of microwave, place 3 peices of cork around center cork and support fishbowl(any peice of glass that is globe like will work, the more like a globe the better) light the toothpick, place glass on top of corks around edge(for ventilation) and start microwave
4. grape, cut the grape in half, then carefully slice the grape again in half, but leave small peice of skin connecting quarters. Fold together to make a flat side and place on microwave floor.
Hints: use old microwave, preferably with clear front faraday cage setup, in addition to this also place a glass of water in the back of the microwave to avoid destroying the magnetio. Tinfoil and other items are fun too, play around and have fun. Ohhh yea, no gerbils etc. Have fun.
Theodore Gray, of Mathematica fame, and recent winner of an IgNobel prize for his wooden periodic table table has a page nicely documenting what happens when you drop sodium into water, which includes a nice quicktime video of a drop of sodium into a lake.
It's psychosomatic. You need a lobotomy. I'll get a saw.
But better than a demonstration is anything hands-on, especially with young kids. You can do some cool stuff with the new neodymium magnets. You can hook up an oscilloscope to a microphone and let them look at their voices. (Or use computer oscilloscope software.)
Find free books.
(or, for the extreme crowd, demonstrating the Leidenfrost effect by sticking one's hand into a vat of molten lead [PDF]).
Ah yes, this would be the one where the paper says, "Never, ever do this.". [If you use too much water, you get a steam explosion that sends molten lead everywhere.]
You might be able to do a safer variant by dipping apples or bananas or what-have-you, though, with a blast shield between the crucible and the audience, though (and a leather apron and gauntlets and visor, unless you *like* liquid metal scars).
The book is chock full of science-geekly fun. The demonstrations are clear and exciting. Kids will love them. The accompanying explanations are in-depth. If you do them all and learn why they work, you'll soak up a fair amount of physics.
Suspend a cinder brick (or other heavy object) from the ceiling with a rope. Pull it back until it just touches your forehead and let go so it swings like a pendulum. It you don't move, it will just touch your forehead on the return swing (or a little short of it). Listen to the gasps of horror from those in your audience who think your head is about to be smashed.
Yet Another Web Site
The Physics department head at the college I attended was constantly doing High school demos.
One I found interesting involved a long aluminum pipe a steel cylinder just small enough to fit in the pipe and a cylindrical magnet (or cylider containing a magnet) of the same size.
First demonstate that the magnet is not attracted to the aluminum by pressing against the pipe.
Then drop the steel slug through the pipe. It should slide through unhindered and quickly fall out the other side.
Now drop the magnet through the pipe. The moving magnet will induce an electric field in the pipe which in turn induces a magnetic field and slows the magnet. And hence it falls very slowly.
Then of course there are the two syringes of different diameter coupled by a plastic tube to illustrate hydraulics.
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
If you were to release the cinder block with the flat side facing you and the rope attached in the middle, were it to turn in mid-swing and come back with at a 45 degree angle to the release position it would most surely split the skin from hairline to eyebrow.
- Get a lightweight, 2-prong extension cord.
- Do not plug it in yet.
- Bare the ends, and wrap them around two medium-large nails.
- Insert the nails into the pickle.
- With all hands off the pickle and the bare metal, plug in the cord.
- Observe that the pickle glows around the contact points with the nails.
Caution:- Never tough the pickle or the bare metal while the cord is plugged in: shock hazard (duh
:-)
- Put the pickle on a non-conductive surface, e.g. sheet of wood.
- Consider doing it out doors, as it smokes and is smelly.
- Adult supervision required. You assume all risk.
Crispin----
Crispin Cowan, Ph.D.
Chief Scientist, WireX Communications, Inc.
Immunix: Security Hardened Linux Distribution
Available for purchase
Do a fourth with 2 parts Hyrdrogen 1 part oxygen it will be about 5 times bigger than the oxygen one (once demonstrated by ISU's SCUM club)
Sigs? We don't need no stinking sigs!
A stream of water is split in two using a tubing "tee". Each stream then is allowed to drop through a bottomless can and into a catching can. The pairs of cans are crosswired and well-insulated. With the water streams breaking up into droplets as they pass through the bottomless cans, an initially slight imbalance of charge is amplified until a spark jumps between them. Typically a 1" spark can be attained after flow of 30 seconds or so. As the charge grows, the water dropplets of each stream repel each other providing an indication of the voltage buildup. If the weather is humid or the insulation of the cans inadequate, the charge leaks away without jumping the gap.
A google search on "Kelvin Water Drop Experiment" gives lots of additional info.
I doubt that... I've had people say roaches will live but they don't. All it takes is the tiny bit of water in their body to boil and pop! their dead. It's a common mistake, the roaches can live with radation but they can not live with the water in their body heated up to a boil.
peek at this site for ideas:
p he re.pdf
http://stanley.chem.lsu.edu/webpub/demo-1-atmos
"There are 11 kinds of people: those who know binary, those who don't, and those who could not care less!"
One of my favorite experiments is to put about 1/4 cup of water in a gallon gas can (the metal kind). Heat it on a stove, burner, etc. until it starts boiling, let it boil a minute or so (until the water vapor pushes out enough of the good ol' ordinary air), then cap it, and drop the whole thing in a tub of cold water. Assuming the cans are still as thin, the can should appear to crush itself, as the water vapor recondenses into 1/1700th (or something like that) of its volume.
By shining a strobe lamp in the darkness onto a fan and varying the strobe frequency you can make it appear to smoothly stop rotating or even make it rotate backwards!
Place two identical tuning forks close by. Hit one and it will start humming. Then silence it with your hand and you'll notice that the one you did not touch is humming too (because of the resonance)
Potassium Permanganate?
It's dark purple, and is rather impressive when mixed with glycerin...
That's why you *never* pour organics down the drain. Ever. Aside from being illegal as hell. Get a big jar, and pour all the organics into that and dispose of them properly.
BTW, unless you have a license, you're not allowed to dispose of acid by neutralizing it with a base and pouring that down the sink. Always remember to make that part of the experiment, otherwise you need a treatment permit.
http://www.inchem.com.ph/hcl.htm
Go read and learn about hydrochloric acid. You sure as fuck cannot buy it at "any pool store" I'm really sick of the kids getting on daddies computer and you mods eat it up like caviar.
I've always been impressed by clock reactions. This time of year, if you can get an orange/black one going for halloween it would be perfect:
p us_a/woodlandm/Demo1.html
http://www.mun.ca/educ/ed4361/virtual_academy/cam
My favorite is creating a plasma ball in a microwave. First light match and put it under a large round glass container (make sure there is ventilation on the bottom so the fire doesn't go out) put inside of microwave, close door, turn it on and watch the fun!
This is a thoroughly spectacular demonstration of many physical and chemical properties and concepts.
Make a dry mix of pulverised Aluminium and Iodine.
Then pour a small cone of the mix onto a fireproof base (my chem teacher used an asbestos sheet, but I'm not sure if asbestos is used in schools any longer). Make a small well in the top of the cone. The mixture is stable, right?
Well, watch what happens to the mixture when you put a single drop of water in the well. You get a plume of purple smoke and a handful of sparks.
The real question to ask the kids is "Why didn't the reaction begin until the water was added?".
IIRC, it goes something like this:
When Iodine dissolves in water, some of it hydrolyses into an acid (hydroiodic?) which reduces the oxide film on some the aluminium, leaving bare elemental Aluminium in contact with water, oxidising it. The heat from the water oxidising the Aluminium sublimes the Iodine, creating the purple plumes and melts more Aluminium leaving bare Aluminium in contact with oxygen in the air, starting the main reaction.
You might want to use a fume hood, though, gaseous Iodine is a little unpleasant.
Ahh - My eye!
The doctor said I'm not supposed to get Slashdot in it!
acutally you induce a magentic feild with an electric current, you pass an electric current though a conductive material and a magentic feild is prodduced, and vice versa, try this, get a multi-meter and hook both leads together, then pass a magnet rapidly over the wire (works best if you have a horseshoe mageitc, and rapidly move the wire up and down thru the middle of the horsshoe magnet) if you have a strong enough maget, or sensitive enough meter, you should see readings on the meter, an analog meter works best in showing the effect. that same principal is at work here, except in reverse.
Sun is Warm, Grass is Green
hehehehe.
;)
HAHAHAHA
(btw that should be N2O; NO2 is poisonous)
Not really sure if the students will respect you too much after you collapse into a giggling heap on the floor after demonstrating the voice lowering effects. Then again, if you let them try it for themselves... For that matter they could make it themselves by gently heating ammonium nitrate (added bonus: heating it too quickly will cause an explosion)
Experiments with nitrous oxide may encourage students to pursue a career in dentistry
"I think it would be a good idea" Gandhi, on Western Civilisation
I do believe you're remembering this incorrectly. Yes, H20 will be the result of burning H2 and O2, but it'll be in the form of water vapor, not a liquid.
Also, remember that H2O expands something like 500+ times in volume when turning into a gas. That would have had to be one helluva balloon to make a "crapload" of water.
http://kered.org
Demonstration of the Ideal Gas Law:
;)
:)
;) http://caselaw.lp.findlaw.com/cacodes/pen/12301-12 316.html
PV = nRT
Pressure × Volume = No. of moles × Universal Gas Constant × Absolute Temperature
First off, you will want to do this outside. All you need is a small amount of dry ice, water, and a plastic soda bottle (20oz, 1liter, or 2 liter are all fine). I would reccomend a 2 liter, because it's more impressive. Put enough dry ice in the bottle to barely cover the bottom of the empty 2 liter bottle. Then be ready for action, because you will want to put about an equal amount of water as dry ice in your bottle. After filling the bottle with water, the dry ice will start being convered to CO2 gas, and you will want to cap the bottle. Place it in the middle of a field or something and make sure everyone is well away from it.
You can take this time to explain that Dry Ice is a solid form of Carbon Dioxide, and when it is in a system with water, it undergoes sublimation (solid to gas, no liquid phase). And that it's gaseous volume is 800 times that of the solid volume. (so if you want to measure and get all scientific, you could).
Just about when you get done explaining this stuff, your experiment should alert you that it's ready. The pressure that the CO2 exerts on the closed volume system becomes too great, and the bottle gives and a rather loud sound is produced. Like everyone said, explosions are cool
So if we apply the science to it.
2 liters = (approx) 2000 cubic centimeters
2000cc/800 = 2.5cc of dry ice needed to fill the system with gas.
So lets say we put 5cc of ice, and 5 cc of water in.
5cc * 800 = 4000cc space needed for the gas to expand
system volume(2000cc) - water volume(5cc) = 1995cc
This would pretty much gaurantee an explosion. But for the kids, you might give them this information and see if they can come up with the minimum amount needed to make the bottle explode, make them draw upon some basic math skills
Ok, now that I've gone though all this, check your state laws to see if this fun experiment is illegal, it is here in california
I much rather like demonstrations that are counter-intuitive. Especially things that seem "supernatural" to do, yet are very natural indeed. I'd like to point out the work of David Willey, whom I've worked with. He organized a world-record firewalk, and I attended (yeah, I've got a world record in firewalking... :-) ).
Check out his article in Skeptical Inquirer: The Physics Behind Four Amazing Demonstrations.
David has done quite a lot of explosions and rocketry too, he knows all about that too, but his best demos is really those that seem risky, but are not. The liquid lead is among them.
Employee of Inrupt, Project Release Manager and Community Manager for Solid
Catalase, aka Hydrogen peroxide oxidoreductase.
2 cm of water in a test tube
A little Li on the bottom
Light a match and put the flame right above the opening of the test tube. When the hydrogen reaches the flame, it will combust with a funny whistling sound.
Just tell the kids not to drop the tubes.. the sound can be quite surprising.
In high school, I was often asked to visit the lower school to do science demonstrations.
The all-time favorite was the Van DeGraff generator. There is something about your hair standing straight out that always amuses the kids. I also lit fluorescent tubes in my hand.
I got the best results by making them stand on a milk crate to keep them from discharging through the floor. Before they got down, I had them "slap me five" so they didn't feel the spark discharge.
You can use the demonstration as a lead-in for static attraction and repulsion and a whole raft of other topics depending on the age group.
Just make sure you get a -small- one. The one I used was 18 inches tall and came from Edmund Scientific.
By the way, if you haven't been to the Boston Museum of Science, then you haven't seen the worlds largest Van DeGraff generator. Quite a show!
http://www.mos.org/sln/toe/
-jake
it's not as bad as you'd think, though. Our bodies are relatively OK with HCl, in small quantities, for short durations.
Ever choke on your own puke? I do, a couple of times a year. I've got reflux, well controlled, but occasionally, I wake up very unpleasantly. Our stomachs put together a pretty decent mixture. Not tremendously high molarity, but still strong stuff. Short exposure to vapor will let you heal soon.
You answered it in your question. The laser goes through the transparent outer balloon. It's absorbed by the colored one inside. Thus, you're heating it, rubber melts, and *pop*.
End of lesson. You may press the button.
Draino is a drain cleaner made mostly from Sodium Hydroxide, also known as Lye.
However, getting pure flake lye is the ideal for this experiment. ( Pure lye can be puchased at hardware stores for drain cleaning/soap making, as well as from pool supply stores.)
What? Me? Worry?
actually any more, they have a harmless chemical that is a VERY good stabilizer (*sigh, been what, 4 years since college chem? You'd think I'd remember this much), which slows down the breakdown process (since H2O is the stable atom, H2O2 is very unstable, thus why it breaks down to H2O and O [the single O being the actual oxidizer] or 2H2O2 => 2H20 + O2 given the lack of a catalist). But the long and short is that you can now keep home or laboratory grade hydrogen peroxide on the shelf for a long time.
I remember in chem class chunking the crust off the H2O2 bottle, and turning my finger tips white just from that (with out getting any moisture on my hands), because the stabilizing agent was so good that even dried there was still plenty of H2O2.
Slay a dragon... over lunch!