xkcd

by **KrO2** » Wed Apr 13, 2011 6:57 pm UTC

Accidental double post removed.

by **KrO2** » Wed Apr 13, 2011 6:57 pm UTC

Sounds interesting. Do you know what concentrations you need? IIRC, the H2O2 they sell is only about 3%., but I don't know about the others.

by **M1k3_Nix** » Wed Apr 13, 2011 7:30 pm UTC

KrO2 wrote:Sounds interesting. Do you know what concentrations you need? IIRC, the H2O2 they sell is only about 3%., but I don't know about the others.

don't really know, have only done the glycerol one myself but a friend has done the peroxide. seem to remember him saying 50% is 'vigorous', but don't remember for sure. to ensure you don't melt the skin on your face off with steam, i would ask google (:

but yea, i dont know for sure :oops:

EDIT: IIRC??

by **KrO2** » Wed Apr 13, 2011 11:05 pm UTC

If I recall correctly. I doubt I'd be able to get concentrated H2O2 out of what I could buy, since it's unstable enough to decompose at the slightest provocation, so I might try the other one.

by **M1k3_Nix** » Thu Apr 14, 2011 5:55 pm UTC

we stock 9% conc. where i work, but we are a very small independent pharmacy. believe upto 35% is quite readily available though.

let me know how it goes with the glycerol (:

-Mike

by **opsomath** » Fri Apr 22, 2011 3:52 pm UTC

When I took AP Chemistry in high school, I did a demo for the regular chem class of the decomp. of hydrogen peroxide using manganese dioxide (basically the same reaction as permanganate). I practiced it using the 3% stuff, which makes nice bubbles that will reignite a glowing splint. However, for the live demo, I decided it would be a fun trick to use the lab-grade 35% stuff instead.

There is a photo of me in my yearbook standing next to a flask with a high-pressure jet of live steam blasting out of the neck and splashing off the ceiling. I am holding a brilliant poker face and praying that it doesn't overflow. My teacher, who is also holding a poker face, came up to me afterward and said "You had no idea that was going to happen, did you." I replied in the affirmative.

by **PhillipC** » Tue May 03, 2011 4:52 am UTC

I must have a different definition of home than most of you... but two easy and entertaining home experiments I know of are:
"Upside Down Water" Take a see through cup, fill with water, and put a styrofoam circle on top (or suitable replacement), then turn upside down! All of you should know how this one works.

"Water Bending" Take a paper or styrofoam cup and poke a small hole in the bottom. Then take a comb and run it through your hair to create a static charge. Fill the cup with water making sure of a steady stream and hold the comb near the stream. Tada! Enjoy the results of watching oxygen atoms be attracted by static electricity.

Also, seems like everyone here as access liquid nitrogen. Putting marshmellows in liquid nitrogen and then eating them is fun.

by **wtspman** » Wed May 18, 2011 8:17 am UTC

You can demonstrate thin-film interference with two sheets of flat glass, a piece of cigarette paper and a monochromatic light. We did this in high school using a mercury vapour lamp, but it should work with other light sources. You lay one sheet of glass on the other placing the cigarette paper (doubled over on itself) between the glass sheets at one end. The paper creates a thin wedge of air between the glass. When you shine the light on the glass, you see a repeating pattern of light and dark bands along the length of the glass.

by **darthchazza** » Mon Jun 06, 2011 12:40 am UTC

wtspman wrote:You can demonstrate thin-film interference with two sheets of flat glass, a piece of cigarette paper and a monochromatic light. We did this in high school using a mercury vapour lamp, but it should work with other light sources. You lay one sheet of glass on the other placing the cigarette paper (doubled over on itself) between the glass sheets at one end. The paper creates a thin wedge of air between the glass. When you shine the light on the glass, you see a repeating pattern of light and dark bands along the length of the glass.

Yeah I always loved this exeriment. We used it in a lab to find the thickness of a human hair that we used to prop the glass open from the line spacing from a given wavelength of light (not very accurate but cool)

by **Philosophish** » Sun Jun 26, 2011 8:13 pm UTC

Rook wrote:Anyway, what I'm really asking for (...) is where I might be able to obtain pressurised gas canisters of that kind of size (...) without too much in the way of monetary expenditure. Free, as it were.

This made me lol.

And think of Douglas Adams' HHGttG writing style.

by **ikrase** » Mon Jul 11, 2011 4:56 am UTC

wtspman wrote:You can demonstrate thin-film interference with two sheets of flat glass, a piece of cigarette paper and a monochromatic light. We did this in high school using a mercury vapour lamp, but it should work with other light sources. You lay one sheet of glass on the other placing the cigarette paper (doubled over on itself) between the glass sheets at one end. The paper creates a thin wedge of air between the glass. When you shine the light on the glass, you see a repeating pattern of light and dark bands along the length of the glass.

Yeah I always loved this exeriment. We used it in a lab to find the thickness of a human hair that we used to prop the glass open from the line spacing from a given wavelength of light (not very accurate but cool)

Machinists use this method to make ultraprecise measurements. They use special superflat glass disks called optical flats. The zebra stripes can reveal problems with flatness, parallelism, etc.

by **ElCarl** » Mon Aug 08, 2011 1:10 am UTC

Quite an entertaining one I've done in the lab was to bubble the gas from the taps into a washing up liquid/water mix.
Loads of natural gas bubbles, add one lit splint - whoosh. Lots of fire

Not much of an "experiment" really, but certainly fun.

by **TaintedDeity** » Mon Aug 08, 2011 2:22 pm UTC

One of my science teachers used to do that. There had always been a bunch of tin foil attached to the ceiling and we didn't know why until he showed us that. Damn awesome.

by **drogas-legais** » Wed Aug 10, 2011 4:12 am UTC

thanks so much for this! I'm a school science teacher and I need to make a kids exposition, those home experiences will help me alot! Many thanks I was lacking ideas!

by **Gaelic rock** » Sat Aug 20, 2011 5:48 pm UTC

ElCarl wrote:Quite an entertaining one I've done in the lab was to bubble the gas from the taps into a washing up liquid/water mix.
Loads of natural gas bubbles, add one lit splint - whoosh. Lots of fire
Not much of an "experiment" really, but certainly fun.

You can do a similar thing by electrolysis on a water/ washing up liquid mix. You need a lot of power to make enough bubbles, fast enough though. Just a few bubbles and you get a nice high pitched pop.

We were going to try and run a little petrol motor off it but we couldn't produce enough gas fast enough, or compress it sufficiently.

by **Arkham** » Tue Aug 23, 2011 6:11 pm UTC

Make a homemade cloud chamber, watch nuclear interactions!

by **yawningdog** » Thu Sep 29, 2011 5:51 pm UTC

When I was in the Army...
Open the heating element of an MRE and pour the contents into a gatorade bottle. (You can use other containers, but Gatorade bottles work best.) Put some water in the bottel with the heater element stuff and close the cap tightly. Eventually the pressure will build up enough pressure to burst the bottle. It's a quite a bit louder than an M-4 rifle.

When I was in the Navy...
We had a parabolical air tracking radar dish that faced aft. We could use the telescope to point the dish at someone on the pier or the fantail of the boat, so that when you put your mouth next to the feedhorn in the center and spoke into it like a microphone, it could be heard a couple hundred feet away like it was someone standing right next to you. A parabolic dish collimates sound just as well as it does RF energy. It's a bit like tapping someone's opposite shoulder from behind just to watch them turn and look at nobody, except it's a lot more effective since there really is nobody there.

Also in the Navy...
Sea Sparrow missile radar can be used to kill seagulls on the wing. Just track them using the camera and energize the transmitter. I didn't actually do this myself, but I had a good friend who was a Sea Sparrow tech who had. Not sure what the max effective range was, but I think it was around 500 meters.

by **gordonmcdowell** » Mon Oct 17, 2011 4:35 pm UTC

This was a very stupid experiment, conducted when I was young... but not young enough to excuse it.

Home stereo. Amiga computer. Speaker wire. Aluminum foil.

Strip speaker wire. Tape onto aluminum foil pads.

Hook speaker wire pads across bicep.(Perhaps you've seen training equipment that looks like this?)

Use sound/music making software to generate different sounds. Experiment with various pitch and volume levels until you find the optimal combination for your no-concentration-required home workout!

This will of course leave small burns on your arm. Something to do with how voltage, current, and resistance in professional equipment is nothing like what one gets out of a home stereo system. However, you just saved a few bucks on buying the real thing!

by **KrO2** » Wed Nov 16, 2011 8:30 pm UTC

Not exactly a home experiment, but I managed to make some pretty good fireballs with methane balloons recently. They have it on tap in one of the science buildings on my campus. I filled a balloon, then sprayed the gas out the end onto a lighter or lit newspaper or something. If you have access to that gas, I recommend it.

by **Alex-J** » Sun Jan 08, 2012 7:31 pm UTC

This was a project I did for my 4th grade science fair (obviously my parents told me what to do

)

Project:
Buy a bag of rubber bands (or utilize an large collection of rubber bands) and put a weight on one end and measured how far they stretch. You need a group of 20 or so that are similar in stretchy-ness. I recommend buying a bag because they shouldn't be too old.

Take an old (small) wheel (mine was around 8 to 10 inches in diameter) take each spoke out and replace it with a rubber band. I did not cut the rubber bands, I may have tied knots or something in the axle's holes where the spokes were. The wheel should be fairly light, you don't need tires or anything on it
When you're finished you should have the rim of the wheel connected to the axle of the wheel only by rubber bands, and when it's laying flat on the floor the wheel's center should be in the center, if not you need to better select rubber bands close to each other in stretchy-ness.

Put a stick or something through the axle, suspending it in air vertically. If you picked a good rubber band size for your wheel size, the spoke length on top will be only slightly less than that on bottom (because of the weight of the wheel) but it shouldn't be too pronounced.

Use a light bulb that gives off heat in a desk lamp, point it at about 10 o'clock on the wheel (put a white piece of paper on other other side to reflect heat back for best results).

Result:
As the rubber bands are heated they'll contract making the radius shorter in that area, making the wheel axle shift to the left, the weight shift will cause the wheel to turn. The wheel will move continuously until the lamp is turned off.

All the project does is demonstrate that rubber bands contract when heated, but you get a really cool wheel that spins itself.

by **nehpest** » Mon Jan 09, 2012 2:07 am UTC

But, which way does it turn? The way I'm visualizing the setup, it shouldn't rotate either way.

by **Alex-J** » Tue Jan 10, 2012 6:42 am UTC

nehpest wrote:But, which way does it turn? The way I'm visualizing the setup, it shouldn't rotate either way.

If you set-up the light at 10 o'clock (pointing at the rubber bands, not the axle or rim) it should turn clockwise. The rubber bands where the light is will contract pulling the axle to the left, the area where the rubber bands are the longest (4 o'clock) should fall toward the bottom (if I'm remembering correctly).

I'd put up a video, but if we ever recorded it it's probably on an old 8mm camcorder tape. (Which we can't even watch now since the camcorder broke over six years ago)

Edit:
A better way to explain this isn't that the axle is "pulled" left, because the axle is in a fixed position, but that the wheel rim (around 10 o'clock) is pulled toward the axle, and the rim around 4 o'clock is pushed further away from the axle.
Thinking about it in those terms (imho) it's easier to imagine the lower-rightward weight-shift.

by **meat.paste** » Wed Jan 18, 2012 5:38 am UTC

You can try gluing a bunch of little square disco ball mirrors to an old satellite dish. It makes a damn effective solar concentrator. There are several videos about this.

by **meat.paste** » Wed Jan 18, 2012 5:50 am UTC

I forgot to mention this one. Take an empty, clean paint can (available at the local hardware store). Drill a small hole in the bottom and a small home in the lid. Put the lid on the can and flush the interior volume of the can with methane until it is basically 100% methane (important: The concentration of methane must be above 25% for safety. Higher is much safer). Set the can up out side so there can be airflow around bottom and top of the can. Light the gas coming out the top of the hole. It will burn like a bunsen burner with the methane being pulled out of the can and air being sucked into the bottom. This will continue and the flame will get smaller until the methane / air concentration reaches the explosive limit. At that point, there is a loud bang and the lid flies off the container. Again, there are videos (http://www.youtube.com/watch?v=MhD5pZ5sZb4 among them)

by **quadmaster** » Mon Jan 30, 2012 3:19 am UTC

If you have a laser pointer and two adjacent fingers on the same hand, you can get single slit diffraction patterns by shining the laser through the gap in your fingers (although aligning everything might take several seconds of practice.) It's about the fastest home experiment I can think of, and it's actually pretty cool to see.

by **PM 2Ring** » Tue Jan 31, 2012 6:04 pm UTC

You can even see single slit diffraction without a laser, all you need is a reasonably bright light source: I can see it just using the light from my monitor. See the Physics Experiment Ideas thread.

But I agree that you get a better result using a laser if you want to project the diffraction pattern onto a surface. Of course, if you're using a laser you should never look into the laser beam!

by **Damiel** » Fri Feb 24, 2012 12:04 pm UTC

quadmaster wrote:If you have a laser pointer and two adjacent fingers on the same hand, you can get single slit diffraction patterns by shining the laser through the gap in your fingers (although aligning everything might take several seconds of practice.) It's about the fastest home experiment I can think of, and it's actually pretty cool to see.

That one is pretty amazing yeah. My whole family was all like :shock:

when I showed it to them.

So thank you.

http://www.procountor.com/kampanjat/kilpailijavertailu/emce

by **MarkVonShief** » Thu Mar 08, 2012 9:26 pm UTC

My son recently got an assignment from his 4th grade teacher to make some physical change in a nail and the kids had about 3 weeks to do it. He wanted to make it rust, so he and his 8th-grade brother put it in a bath of salt water and watched it for a few days. Nothing. Then they tried vinegar - also nothing after a few days. I suggested applying a little electricity to the setup, so soldered a piece of copper to a 12V wall-wart for the cathode and clipped the anode onto the nail and put it in a bath of table salt in water.

I was not ready for the speed of the reaction. Within an hour, the water had turned black and there was a layer of scum and metal flakes that had been shed on top. We stopped that experiment after a few hours and he wrote it up. So next, he did a similar thing with a new nail, this time in a bath of vinegar. The reaction rate was slower but progressed much further before we shut it down the next day. The nail was caked with rust, the brass clip had all but dissolved and the copper cathode was discolored.

This was an outstanding experiment and the teacher deserves kudos for giving the kids something so completely wide-open as to cause a physical change in a nail.

Our next series of experiments, sometime soon, is to electroplate the nail with copper.

- MVS

by **PM 2Ring** » Fri Mar 09, 2012 2:43 pm UTC

MarkVonShief wrote:Our next series of experiments, sometime soon, is to electroplate the nail with copper.

Some suggestions:
• Prepare the nail using fine sandpaper and once it's sanded don't touch the section you intend to electroplate. If you do accidentally touch it, clean it with alcohol, since oils from the skin will interfere with the plating process. Even a single molecular layer of oil can inhibit adhesion.
• Make sure your anode is large enough to supply the amount of copper that you want to plate onto the nail and make sure it's clean, although that's not as important as a clean cathode.
• Use a low current. A high current will cause a faster rate of deposition, but it can also cause tiny pockets of electrolyte to get trapped under the plating. A low steady current will give a much more solid plating that's less likely to flake or peel off. If you can't control the current and have to use a high current source, then reduce the concentration of the electrolyte.
• Keep the temperature as constant as is practical, since variations in the temperature will cause variations in the rate of deposition, which once again will affect the evenness of the plating.
• Prepare the electrolyte using deionised or filtered water, not plain tap water, since the ions in the tapwater (especially chloride) can affect the colour of the plating.
• If possible, arrange some way to stir the electrolyte to keep it homogenous.

Also see http://en.wikipedia.org/wiki/Galvanoplastic_sculpture

by **MarkVonShief** » Fri Mar 09, 2012 3:27 pm UTC

@PM 2Ring - thank you for the suggestions.
I had mentioned this experiment to a metalurgist a few weeks ago; he suggested putting a little bit of soap into the solution to keep the electroplating process at the surface of the steel and not to grow (spinoidally) over areas already plated (there is a term for this - I've seen this in semiconductor work, but it escapes me at the moment).

This is worth a sub-experiment in itself.

- MvS

by **Sanddancer** » Mon Apr 16, 2012 6:32 pm UTC

Came across this in Scientific America (I think) just last week. Copper metal suspended over acetone in a glass jar (wicks included to help saturate the air). The result is brightly glowing copper without (i need some convincing here) the acetone igniting. I'm assuming this must be some sort of catalytic "low temp." ignition of acetone on the copper surface.

I'm trying to persuade myself that this would be a safe middle-schooler science project.

http://www.youtube.com/watch?v=wt7QeA0zBKw

by **madd0ct0r** » Fri Jun 15, 2012 3:28 am UTC

i'm not sure anything involving acetone can be said to be safe (although i have heard that bubbling it through copper sulphate solution gives you a paste that explodes after drying out)

for electroplating fun powdered graphite can be used to electroplate non-conductive stuff (like leaves or shoes) - good introduction to semi-conductors.

finally, I remember an old home experiment for measuring the calorie content in food. Light it on fire under a pot of water and measure the tempreture change.

there's got to be a more accurate set up though...

EDIT: got acetlyne and acetone mixed up. just as well i wasn't bleaching my hair...

by **robotcl** » Fri Jun 15, 2012 2:32 pm UTC

Not sure dropping a bag of some kind of retro sweets I bought online into a 1.25L cola bottle and made it exploded it the matter of couple of seconds. You don't want to know how it ended :cry:

, let's just say I never looked up in my bedroom again. :mrgreen:

Can't remember what was the sweets, so if anyone have any clue, do share please!

by **madd0ct0r** » Wed Jun 20, 2012 2:20 am UTC

from the mythbusters episode dedicated to that - you want a sweet with a nice rough surface area for bubble formation.

It might have been those fzzy chews - which was sherbet wrapped in a sugar case. The case dissolves and then you get the fountain.

by **Philosophish** » Sun Sep 23, 2012 1:04 am UTC

Philosophish wrote:
Rook wrote:Anyway, what I'm really asking for (...) is where I might be able to obtain pressurised gas canisters of that kind of size (...) without too much in the way of monetary expenditure. Free, as it were.

This made me lol.

And think of Douglas Adams' HHGttG writing style.

Hahahaha, I read this and went "Yeah made me lol too - and indeed reminds me of adams! who is this guy??"

turned out to be me -a year or so.. :')

by **wumpus** » Thu Sep 27, 2012 3:41 pm UTC

M1k3_Nix wrote:
KrO2 wrote:Sounds interesting. Do you know what concentrations you need? IIRC, the H2O2 they sell is only about 3%., but I don't know about the others.

don't really know, have only done the glycerol one myself but a friend has done the peroxide. seem to remember him saying 50% is 'vigorous', but don't remember for sure. to ensure you don't melt the skin on your face off with steam, i would ask google (:

but yea, i dont know for sure

EDIT: IIRC??

I remember my high school chemistry teacher claiming that concentrated H₂O₂ was the nastiest chemical he'd ever seen. While I don't expect he was all that familiar with "stuff I no longer work with", I don't doubt just how dangerous it can be.

Also check John Carmack's post 9/11 rants about obtaining the stuff. No idea if it is any easier to obtain.

by **webgiant** » Mon Oct 01, 2012 3:38 am UTC

I enjoy making wood charcoal, weighing smoke (a close approximation), and exciting sodium atoms in pickles to make them glow.

For the first, take a large juice can. Put one hole in the side with a "church key" can opener, and drain the juice. Thoroughly wash and dry the can, removing the outer label. Then take small pieces of wood, preferably hardwoods, that can fit through the hole in the can, and fill the can about one-third to one-half full. Heat the can on a stove burner. As wisps of smoky-looking gas come out the hole in the can, light them with a lighter. Continue heating the can until the flame goes out. Allow the can to cool, then cut open the top of the can with a can opener and pour out the nearly pure carbon charcoal inside.

This experiment covers principles of making charcoal--which is called "coke" when you do the same basic process using coal--and also covers the basic principles of a wood gasifier. A flammable gas is produced when the wood is heated, which can be used in many applications currently handled by natural gas. Wood gasifiers using waste sawdust from sawmills currently fuel a number of pickup trucks, where the sawdust is used both as the gas production material and the heat production material.

For the weighing of smoke, the home experiment version is largely unchanged from the time Sir Walter Raleigh won a bet with Queen Elizabeth I by doing the same experiment.

Take a lump of wood. Weigh it. Then completely burn the wood, without using any accelerants. Weigh the resulting ash. Subtract the weight of the ash from the weight of the wood, and you have the approximate weight of the smoke. It is only an approximate weight because the process of oxidation adds weight to the smoke by sucking in oxygen from the surrounding air, oxygen not present in the original lump of wood. However, this experiment is enough to wow nerd groupies who don't completely understand oxidation but who realize that some of the richest billionaires in the world are nerds.

Finally, during your next Halloween party, you can do the "Frankenpickle" (okay, it would be Frankenstein's monster pickle, but literary pedantry has no place in mad science). You will need a small wood board eight inches by four inches by half an inch thick, two long nails, a dill pickle (sweet pickles don't seem to work as well as dill), two alligator clips rated for the voltage of the power in your part of the world, and an old lamp cord from a broken lamp (the idea is a plug and two wires). Affix an alligator clip to the end of each lamp cord wire.

Pound the nails through the board, slightly less than the length of your dill pickle. Impale your dill pickle on the two nails. Clamp a wired alligator clip on each nail. Get ready to plug it in and have someone else turn off the lights, or use a switched outlet and turn the lights off before switching on the pickle. The pickle will glow with a satisfying electrical crackle, and an even more satisfying "Frankenstein's monster being charged with lightning" green glow. You have just used electrical energy to excite the sodium molecules in the pickle to glow with an unearthly light.

by **eulerIV** » Mon Nov 19, 2012 11:44 pm UTC

I prefer those which says "Dont try this at home..." ^^

by **Xenomortis** » Tue Nov 20, 2012 10:26 am UTC

The microwave method is definitely the tastiest.
And also the easiest, but that has nothing to do with it.

by **kurukkan** » Mon Feb 18, 2013 8:36 pm UTC

oxoiron wrote:
Also, and I just saw this the other day, here is "anti helium". Sulfur Hexaflouride gas, which is inert, but about 6 times denser than air.

Try inhaling SF6 as you would helium (in small, controlled, low-pressure amounts). Instead of making your voice squeaky, it makes it unnaturally deep. The squeaky He voice and the deep SF6 voice occur because your vocal chords produce sound by vibrating in one gas or the other and the sound produced travels at different speeds in each gas. By the time the sound reaches an observer's ears, it is in normal air and the speed has changed, thus altering the perceived frequency.

FIND THE HALFLING

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