Sciencemadness Discussion Board - I want to hear your favorite chemistry demonstrations

I want to hear your favorite chemistry demonstrations

Pages: 1 2

SAACS - 6-2-2014 at 08:42

Every year our university chem club goes to a children's museum and conducts some interesting demonstrations for the age range of roughly K-5. Some examples are: gummy bear + KClO3, elephant toothpaste, and a ball pit explosion using a bottle filled with LN2 in a trash can. We bring plenty of LN2 and have access to a lab and other ways of getting any necessary materials. The only caveat is that while we can work inside or outside, we have no fume hoods at the children's museum.

What demonstrations do you like the most?

Pyro - 6-2-2014 at 08:44

chemical chameleon is nice

Zyklon-A - 6-2-2014 at 08:55

Water-initiated flash powder.
Chloric acid (from KClO3+H2SO4) and sugar.
Aluminium and iodine plus a few drops of water.
About .5 gram NH₃, nice iodine vapor, initiated with feather.
Sodium peroxide + sugar and add drop of water to get going.

[Edited on 6-2-2014 by Zyklonb]

Mailinmypocket - 6-2-2014 at 08:56

Tossing a small scooop of KMnO₄ into a tall beaker with a small layer of 35% H₂O₂ in the bottom makes an impressive little mushroom cloud poof out. Be careful though, it is like elephants toothpaste but can spit a little if you use too much peroxide or the container is too small. You can also submerge a glowing splint into the beaker to demonstrate O₂.

Brain&Force - 6-2-2014 at 09:30

Fluorescence of pyranine (found in highlighters)
Tollen's reagent
Bismuth diamagnetism
Coordination chemistry of Ni²⁺ and Cu²⁺ with ethylenediamine, ammonia and chloride
Burning magnesium and spraying water on it
Gummy bear in chlorate
Flame tests in methanol/ethanol
Fake blood (iron thiocyanate)
Heating iodine
Reaction of aluminum with iodine
Ammonium chloride smoke
Aluminum with copper chloride/HCl
Alkali metals in water
Precipitation of unusually colored precipitates (cobalt hydroxide, lead iodide)
Dichromate redox
Iodine clock
I could go on forever...

[Edited on 6-2-2014 by Brain&Force]

Zyklon-A - 6-2-2014 at 09:35

What do you mean ''Burning magnesium in water''? Do you mean spray water on a burning Mg ribbon, or what?

Mailinmypocket - 6-2-2014 at 09:44

Burning Magnesium in Water

MrHomeScientist - 7-2-2014 at 07:28

I actually do a science stage show for the same target audience. We go to local elementary schools and do a 45 minute show to get the kids interested in STEM (Science, Technology, Engineering, and Math) career fields. We have videos and a couple experiment descriptions on our website, www.sciencebrothers.org .

My favorite demonstration of our show is the Barking Dog. Thanks to woelen here on this site, I use a much safer version that produces a green flame instead of the usual blue*. Elephant Toothpaste is probably the most popular with the kids. The chemical traffic light is also pretty good and simple, and by using the same chemicals with a different dye you can change it up and perform the Blue Bottle demo.

I really enjoy doing the show. It's a great feeling to see kids get so excited about science. Good luck with yours!

*Edit: To clarify: it's safer because it replaces carbon disulfide with methanol with a little boric acid dissolved in it. The standard barking dog produces sulfur and sulfur dioxide as products, which make cleaning the tube annoying and produces sore throats, respectively. Using methanol/boric acid instead results in harmless byproducts (boron trioxide, most likely) and the tube cleans out easily with a water rinse.

[Edited on 2-7-2014 by MrHomeScientist]

confused - 7-2-2014 at 07:52

i like the iodine clock reaction, never fails to amaze people

sargent1015 - 7-2-2014 at 10:00

By far my favorite demos are:
1) Hydrogen Balloons
2) Metal salts in a flame
3) Whoosh Jug (Ethanol in a large office water jug, vaporized, and ignited)

-Sarge

Ascaridole - 7-2-2014 at 14:15

1) Oxidation states of Vanadium using amalgamated zinc and Cerium (IV) to re-oxidize it back to its so so yellow: Kinda advanced but shows some nice analytical technique with beautiful color changes especially the 3+ blue… mmmm….ok maybe not for K-5 but hey it hooked me on chemistry….

2) Liquid oxygens paramagnetism and blue color: Nice way to talk about spin and free electrons and the color blue… also good for showing big flames at the end.

3) Thermal decomposition of Iron oxalate to pyrophoric Iron: Fire is always nice, fire is even more fun when all you need is air…. nice way to show how a nail can catch fire if you can smash it up enough. Oh and you can even drop the pyrophoric iron into the liquid oxygen for a big kicks!

Zyklon-A - 7-2-2014 at 19:45

On a related note to 'Burning Magnesium in Water', Al can also react with water in an even more spectacular way than the Mg in the video. Make an un-stoichiometric 'flash powder', by mixing about 1 gram of KClO₃ for every 4.5-6 grams of Al.*
Light it with a fuse and then wait for it to stop burning, then most of the Al will not have burned, but it will still be glowing red hot. Take a syringe (or pipette) full of water and spray a lot of water on the pile of glowing Al. It will instantly burst into a bright white flames as the Al reduces the water to H₂ , and on top of the pile the H₂ will react with more oxygen in the air and give off a nice blue flame, very pretty.

*The reaction looks much better in larger quantities than 1g KClO₃ and ~5g Al. For best results try 3g KClO₃ with ~15g Al. If a lot of water is sprayed on that, it will likely Fizz for a couple seconds then erupt into bright white flames, shooting burning Al in all directions! (looks a lot like fireworks).

Be very carful with this and if you show the reaction to kids, absolutely do not do it inside! Also try it a few times yourself before showing to anyone, just to get the hang of it. And wear all necessary protective clothing, if the reaction goes well, it is worth the effort.

[Edited on 8-2-2014 by Zyklonb]

alexleyenda - 7-2-2014 at 20:08

I'll answer
this : http://www.youtube.com/watch?v=2udiRj6vYag

and this : http://www.youtube.com/watch?v=h4pNXAtPJp8

The first one is way too toxic to be performed without fume hood with kids, but it is so great

The seconth one might be doable outside.

Also, simply "dissolving" styrofoam into acetone can be rather impressive and this one is totally safe! http://youtu.be/6S4zfMdjQxY?t=1m11s

[Edited on 8-2-2014 by alexleyenda]

Zyklon-A - 7-2-2014 at 20:19

Wow! That first video was badass, I've seen both of those reactions, but not at the same time.

alexleyenda - 8-2-2014 at 09:36

Yup both at the same time is really awesome, it looks like the doors of hell opening :p

Chemosynthetic - 14-2-2014 at 19:22

I'm really glad to hear people are still involved in their communities with science outreach. I always liked iodine clock and oscillatory reactions since they really made me see equilibrium in a different manner than prior.

sasan - 22-2-2014 at 22:49

Try a drop of CS2 and let it avaporate in a measuring cylender and ingest N2O with a syrenge into the cylender.there will be very bright blue light and a strange sound,barking dog!!!!

Mailinmypocket - 2-4-2014 at 04:51

This isn't the coolest or my favorite but I did find it original, that's for sure. Blue bottle demo, edible style.

http://www.stevespanglerscience.com/color-changing-powerade

MrHomeScientist - 2-4-2014 at 06:15

That's astonishing. Great find!

The standard blue bottle requires dextrose, sodium hydroxide, and methylene blue. In his version, the dextrose would be from the Sweet N Low and I imagine the dye is in the Powerade. But tonic water is acidic, so there must be something in the cinnamon Altoid, and only the cinnamon variety, that basifies the solution. Very very interesting. I wonder how he discovered something like that; seems like a pretty random combination.

DraconicAcid - 2-4-2014 at 07:28

Quote: Originally posted by sasan

Try a drop of CS2 and let it avaporate in a measuring cylender and ingest N2O with a syrenge into the cylender.there will be very bright blue light and a strange sound,barking dog!!!!

Please note- the word you want is "inject". To ingest something means to eat or drink it. (And I think the barking dog uses NO, not N₂O.)

MrHomeScientist - 2-4-2014 at 08:13

I routinely perform the barking dog with nitrous oxide, N₂O, and it works great. And you need a source of ignition to get the reaction to start - just mixing CS₂ and N₂O in a flask doesn't do anything.

forgottenpassword - 2-4-2014 at 08:24

Would helium affect the pitch of the bark?

DraconicAcid - 2-4-2014 at 09:10

Quote: Originally posted by MrHomeScientist

I routinely perform the barking dog with nitrous oxide, N₂O, and it works great. And you need a source of ignition to get the reaction to start - just mixing CS₂ and N₂O in a flask doesn't do anything.

Okay. I do know that it *does* work with NO- I was shown how to do it, generating NO from copper/nitric acid (and scrubbing the gas well with water to remove NO₂, which would have detonated).

NedsHead - 24-3-2016 at 04:20

I tried to perform the elephant toothpaste reaction many times today without very impressive results,

I first tried 50ml of 50% H₂O₂, 5g potassium iodide solution, 25ml kitchen detergent (poor result) followed by the same amounts but replacing the kitchen detergent with sugar soap ( a little better this time)

Then I tried the same amounts of H₂O₂ and potassium iodide with a much smaller, unmeasured amount of sugar soap but still didn't achieve the impressive expansion of foam expected with this novelty reaction.

I thought it could be an issue with the 2 different bottles of H₂O₂ I tried and have had in storage for a long time so I bought a fresh bottle at the local hydroponic store but still had the same results.

Any ideas what might be going wrong?

MrHomeScientist - 24-3-2016 at 09:22

Three things:
- How concentrated is your "potassium iodide solution"?
- You're using a ton of soap, which I'm sure is diluting and slowing the reaction.
- You can easily check the concentration of your peroxide to make sure it hasn't degraded by measuring the density, and using this calculator.

Our version of elephant toothpaste uses 125mL of 35% H<sub>2</sub>O<sub>2</sub> with maybe < 10mL liquid dish soap, just enough to lightly color the solution and produce bubbles. To this we quickly add a solution of 12g KI in 10mL water (so, a saturated KI solution). This is done in a 1000mL plastic graduated cylinder, and shoots a column of foam out the top several feet in the air.

One time the manufacturer accidentally filled one of our 35% bottles with 50% peroxide, and using the same conditions as above blasted the foam out instantaneously, spraying hot foam onto the presenters. Scary situation. Now we test each new bottle of peroxide before use. Be careful with that strength of peroxide.

Deathunter88 - 24-3-2016 at 10:30

Quote: Originally posted by Mailinmypocket

This isn't the coolest or my favorite but I did find it original, that's for sure. Blue bottle demo, edible style.

http://www.stevespanglerscience.com/color-changing-powerade

Quote: Originally posted by MrHomeScientist

That's astonishing. Great find!

The standard blue bottle requires dextrose, sodium hydroxide, and methylene blue. In his version, the dextrose would be from the Sweet N Low and I imagine the dye is in the Powerade. But tonic water is acidic, so there must be something in the cinnamon Altoid, and only the cinnamon variety, that basifies the solution. Very very interesting. I wonder how he discovered something like that; seems like a pretty random combination.

I hope you guys realise that was an April fools joke and does not actually work. (I admit I got fooled when I watched it the first time

)

[Edited on 24-3-2016 by Deathunter88]

MrHomeScientist - 24-3-2016 at 10:33

Damn! He got me good.

I may actually have a chance to meet him next month, so I'll have to accost him for his treachery!

ave369 - 24-3-2016 at 11:53

Neutralization of sulfuric acid with bicarbonate of soda, with crystal violet added to the acid. Because of it, not only it foams, it displays nice color changes from yellow to violet.

NedsHead - 24-3-2016 at 18:31

MrHomeScientist

My Kl is a saturated solution, I add just enough water to disolv the 5g of Kl,

I also thought the amount of soap could be diluting the reaction but when I used considerably less the reaction improved only slightly,

I did do a quick test of the peroxide by dropping a piece of MnO₂ into a sample of each, the two old bottles of peroxide reacted mildly, the fresh bottle reacted strongly and produces a thick amount of O₂ vapour from the test tube, I'll test the exact concentration of the peroxide like you suggested.

I'll try your measurements and report back

Velzee - 24-3-2016 at 19:25

My favorite demonstrations that my chemistry showed us are: metallic sodium verses water, making/igniting gunpowder, the "screaming" gummy bear, and the power of methanol(shooting a five gallon water jug across the room using only a few drops of methanol). But I honestly can't get enough of the old 'pop!' you get when igniting hydrogen gas in a test tube.

crystal grower - 25-3-2016 at 03:26

Hot ice is simple and nice, thermite reactions of course

, potassium permanganate + sulfuric acid, explosion of plastic bottle filled with dry ice, pyrophoric iron.

brubei - 25-3-2016 at 03:30

yeast fermentation, beer, yogourt

interdisciplinarty is fun too

100PercentChemistry - 25-3-2016 at 09:25

Fascinated by oscillating reactions. So little are known.

Dan Vizine - 31-3-2016 at 12:53

Manganese thermite. Outside and from a distance.

100PercentChemistry - 1-4-2016 at 07:09

Simple yet amazing reacrions.

careysub - 19-4-2016 at 16:52

My favorite demonstration that I have seen (not performed) is the endless nylon rope trick produced from hexamethylenediamine and sebacoyl chloride which I saw performed at the Dow Chemical pavilion at the New York World's Fair in 1964 when I was 7 years old.

I have wanted to get the chemicals to perform this myself, and I have a quote for them. Anyone interested in a getting set up for this demonstration also?

j_sum1 - 19-4-2016 at 17:08

I will be doing that one for my class in the next couple of weeks.
I have not really found it satisfying -- My attempts have consistently turned out clumpy. I thought the chems were old and deteriorated but even buying new ones didn't help. Let's see how we do this year. I might make the solutions more dilute and see how that works.

solitanze - 24-4-2016 at 08:13

Cellulose nitrate, from nitrating cotton balls.
Bleaching a red potato or onion with sulphur dioxide gas (from metabisulphite and dilute acid).
Ammonium dichromate volcano.
Reacting tin sheets with a few mL of bromine in a large test tube. Very strong exotherm. The liquid is impure tin tetrabromide, it solidifies when holding the tube under cold running water.

j_sum1 - 12-5-2016 at 03:09

I have been sitting on these for a while. They contain a number of great and dramatic chemistry demonstrations. many of the are a bit on the dangerous side. Some use chems that are not readily available. But there are a bunch of classics and some lesser-known and very cool reactions.

Enjoy.

These might be suitable for uploading to the SM library.

Attachment: Chemical Demonstrations Resource Book 1.pdf (6.1MB)
This file has been downloaded 5393 times

Attachment: Chemical Demonstrations Resource Book 2.pdf (6MB)
This file has been downloaded 1308 times

skip - 12-5-2016 at 17:18

luminol fountain

JJay - 12-5-2016 at 22:05

Chem Player has done some pretty cool cyanide demonstrations recently

j_sum1 - 7-10-2016 at 22:22

I recently did chlorine / acetylene spontaneous combustion. Nice and dramatic. Procedure in book 2, linked two posts upthread. Experiment 101, page number 164.

Morgan - 8-10-2016 at 06:05

Quote: Originally posted by j_sum1

I have been sitting on these for a while. They contain a number of great and dramatic chemistry demonstrations. many of the are a bit on the dangerous side. Some use chems that are not readily available. But there are a bunch of classics and some lesser-known and very cool reactions.

Enjoy.

These might be suitable for uploading to the SM library.

The lycopodium balloons seemed like a clever way to atomize the powder (page 103 book 1) and enhanced by using oxygen.
Also the other fuels that didn't work for the author but were suggested sounded worth a try or challenge.

PROCEDURE B
Place about 0.5 g (about I teaspoon) of lycopodium powder in each of two like colored balloons, about 1 g (about 1 teaspoon) of corn starch in each of two more balloons. and about 1 g (about 1 teaspoon) of flour in the last two balloons. Inflate one balloon in each pair with compressed air and the other with oxygen. In sequence. place each balloon on a ring attached to a stand and ignite with a candle mounted on a meter stick. Observe each explosion and note the differences in sound intensity and flame size. Note the effect of combustion in the oxygen-filled balloons compared to the air filled
balloons.
Although Reinstein and Shaver [21 suggest using additional solids, such as powdered milk, powdered sugar, and coal (ground with methanol and allowed to dry), we have not had success with these substances.

Also I wonder if a flame of hydrogen and chlorine would emit enough UV light to fire off a vessel of hydrogen and chlorine instead of using a UV LED, magnesium ribbon, sunlight, or 300 watt slide projector bulb. Sort of a variation on a theme of this clip.
https://www.youtube.com/watch?v=dBF3cfsPPOM

Or might the light from these high voltage modules I purchased long ago activate hydrogen and chlorine inside a stoppered quartz tube if held near? They're tiny sparks but kind of bright on the eyes.
https://www.youtube.com/watch?v=d33_Fhgy5Dg

Perhaps if you had a quartz prism and full spectrum light source it might be fun to darken the room and move the test tube of hydrogen and chlorine along the rainbow and try to see if it fires.

[Edited on 8-10-2016 by Morgan]

Morgan - 31-1-2017 at 08:07

Yesterday I was toying with a pale yellow mushroom that forms a sack with a goodly amount of spores inside, the kind that billow a lot of smokey spores when popped. The mushroom wasn't some perfectly round kind you sometimes see but an odd very light weight, pale yellow and brown, elongated bumpy membrane somewhat egg-shaped and it didn't seem to have an pronounced attachment point where it rooted to the ground. So the thought was to see how the spores might burn if held next to a lit Bic lighter.
Surprisingly, when the partially split sac of spores was compressed near a flame the fireball the burning spores made was quite perky, reminiscent of lycopodium powder. So if you had a large amount of these which were collected for their spores, perhaps they'd be a comparable/alternative "dragon's breath" source, slightly quirky or road less traveled.

I wonder if you had someone standing by with a lit propane torch if this puffball spore cloud would burst into flames?
https://www.youtube.com/watch?v=5TeFsg9e-ks

After looking over some photos I think it's possible that the mushroom I found was an earthstar as there were a few dozen banana peel looking things in my lawn that came after some rains. If you look at the 3rd photo that's sort of what my flammable spore ball looked like but more of a potato shape without the perfect round shape with a pointy top.
http://www.realmonstrosities.com/2013/06/earthstar.html
Or it could have been something like this poisonous earthball.
http://www.wildutah.us/html/plants_scenery/h_mushroom_earthb...

[Edited on 31-1-2017 by Morgan]

Chlorine - 31-1-2017 at 13:03

My absolute favorite demonstration is the formation of Aluminium tri Iodide.

3g of Iodine and 4g of powdered aluminum added to a wide mouthed crucible. Once thoroughly mixed, add enough water to wet the mixture. Since the reaction is extremely exothermic the excess iodine sublimes into a beautiful purple vapor.

Melgar - 2-2-2017 at 15:00

Quote: Originally posted by j_sum1

I recently did chlorine / acetylene spontaneous combustion. Nice and dramatic. Procedure in book 2, linked two posts upthread. Experiment 101, page number 164.

Would this work with methylacetylene? A friend borrowed one of those yellow propylene torches from me and used it all up, so he gave me back an old one his dad wasn't using, that actually had real MAPP gas in it. I don't see why it wouldn't work, but don't want to do anything stupid either.

I tend to be biased towards demonstrating reactions I've personally been working on, so showing the reaction between aluminum and galinstan, and then water is always fun.

Methanol + boric acid poured on the sidewalk and set on fire at night is always really cool. Methanol and propylene glycol will both burn with a green flame, but neither isopropanol nor ethanol will.

The haloform reaction can be impressive to some people, although you don't necessarily want to show grade schoolers how to make chloroform.

The three-stage thermite reaction is pretty impressive if you are able to do it outside. Basically, you mix thermite like usual, then mix potassium permanganate with aluminum and put it on top of that. Add a little extra potassium permanganate on top, then drizzle glycerin on top and step back. The KMnO4 will oxidize the glycerin, eventually producing enough heat to cause it to catch on fire. This will set off the flash powder underneath it, which in turn will ignite the thermite. It makes for a pretty dramatic sequence of events.

j_sum1 - 2-2-2017 at 16:19

I think you would get a reaction. But I would try small scale first. Changing your fuel molecule will undoubtedly change the kinetics and you really don't want something too vigorous or getting out of control.
The nice thing about this demo is that the acetylene is produced in situ from solid CaC2 and then reacts with the Cl2. This gives a series of pops and flashes that stay reasonably well contained.

Scalebar - 3-2-2017 at 01:47

I like doing calcium metal in water - it's the about the most reactive things I'm comfortable letting six year olds handle ( with a lot of supervision ), they get to light the hydrogen and no one ever does calcium, plus most kids will tell you 'calcium is bones' - even many adults don't realise it's a soft white metal. You can burn pieces in air as a finish to the session.

j_sum1 - 3-2-2017 at 02:01

I have always had difficulty in getting Ca to ignite.

Melgar - 3-2-2017 at 03:30

Quote: Originally posted by Scalebar

I like doing calcium metal in water - it's the about the most reactive things I'm comfortable letting six year olds handle ( with a lot of supervision ), they get to light the hydrogen and no one ever does calcium, plus most kids will tell you 'calcium is bones' - even many adults don't realise it's a soft white metal. You can burn pieces in air as a finish to the session.

Aluminum/gallium/indium alloy at 96:3:1 is air-stable, reacts vigorously with water to generate hydrogen, can be safely handled with bare hands, as long as they're dry, and even when they're wet, the worst that'd happen is a mild burn from the heat of the reaction. The gallium and indium can be recycled afterwards. Not sure if this information is useful to you or not, but if you're ever in a bind, it could work as a decent stand-in.

Scalebar - 3-2-2017 at 06:35

Quote: Originally posted by Melgar

Is that an alloy that can be home made? I've plenty of gallium and a frankly alarming quantity of aluminum powder.

Re: Igniting calcium - I put three or four pieces on a vermiculite tile and hit it with a pencil blow torch. It does take a couple of minutes to catch but it's lovely shade of red - if 'shade' is the right term for something so bright it's like taking a scarlet hammer to your retinas.

Bezaleel - 3-2-2017 at 16:28

Quote: Originally posted by Chlorine

My absolute favorite demonstration is the formation of Aluminium tri Iodide.

3g of Iodine and 4g of powdered aluminum added to a wide mouthed crucible. Once thoroughly mixed, add enough water to wet the mixture. Since the reaction is extremely exothermic the excess iodine sublimes into a beautiful purple vapor.

Lovely! This was one of the demo experiments at the stsrt of our chemistry class in high school. It didn't ignite well, but after it was aided with a Bunsen burner, it went off with great vigour. Although the fume hood was closed right away, we enjoyed the slowly paling ocre stains on the ceiling for the remainder of that school year

A personal favourite is the chameleon reaction between solutions of Cr(III) and ammonium paramolybdate, which ends in an Er(III) like coloured solution.

What I love to demo is the boiling of tap water when pulling a vacuum. If you pull down to a mbar and wait untill boiling has ceased, the water will be around 15 centigrade. The influence of dissolved salts present in the water on the drop of the bp is just stunning.

NeonPulse - 3-2-2017 at 17:40

Aluminium in bromine looks neat but my favourite demo is sodium and lithium metals into liquid ammonia. I love the way these little blue tendrils reach out from the metal at first and then form that brilliant blue solution of solvated ions. When the metal first begins dissolving it looks awesome and it is equally cool to see a coppery mirror form when enough metal has been used.

Melgar - 4-2-2017 at 23:44

Quote: Originally posted by Scalebar

Quote: Originally posted by Melgar

I've been making this alloy quite a lot recently, to test its usefulness in organic reductions. I just melt down the aluminum with a propane torch, then mix in eutectic gallium/indium (3:1 ratio, 15˚C mp) when it's molten, typically at a ratio of 20:1 or so. When it solidifies, the gallium and indium separate out along grain boundaries, which makes the resulting material very brittle. I can break it using two pairs of pliers easily.

Aluminum powder doesn't work for this though, at least not using the setup I have. The torch would blow your aluminum powder everywhere, and it's really hard to get the particles to melt together anyway. But if you have a kiln or can melt down your aluminum somehow, then it should work fine. However, I've found that 3004 aluminum alloy is much more reactive than every other alloy I've tried, probably because there's a small amount of magnesium in it. This is actually the same alloy that's in soda cans, but it's much easier to melt down those disposable aluminum serving trays, and I can get three 30-gram trays for $1 at my local dollar store. I usually twist them up into a rod shape, as tight as I can get it so that there aren't so many insulating air pockets, then hold the torch at the base while I push the rest of it into the molten aluminum puddle with a pair of pliers. I have a thread with pictures in the prepublication forum.

Incidentally, if you need any indium, I just got over a pound of it, and am selling it here for fifty cents a gram plus shipping from New York City.

[Edited on 2/5/17 by Melgar]

Morgan - 16-8-2017 at 12:55

I did this this morning, didn't amp up or modify the sound in any way yet it's incredible how loud a simple tube with some methanol in it can be. I'd put this up against the typical barking dogs almost, the ones with N2O or NO2 enhanced oxygen sources. It killed my ears even as small as it is. If you listen to it at half speed you can really hear the reverberation.

Barking Dog Chemistry Demonstration With Methanol
https://www.youtube.com/watch?v=gxtllHrFTjU

[Edited on 16-8-2017 by Morgan]

Foeskes - 16-8-2017 at 15:44

Disappearing potassium permanganate:
Add a pitch of KMnO4 to 100 ml of water. Then add 10 ml of vinegar. Now ad some thiosulfate solution while stirring.

nezza - 17-8-2017 at 01:07

Some simple precipitation reactions. Mixing colourless substances to form a coloured precipitate or to give different coloured precipitates. The only problem is the most striking ones use hazardous compounds :-

Lead salts + iodide (colourless) > lead iodide (yellow). This can then be warmed and some lead iodide will dissolve separating out in golden plates as the solution cools.

Silver nitrate + potassium chromate (yellow) > silver chromate (brick red)

Another one is the classic crystal garden setup. Dilute water glass down and drop crystals of coloured salts (copper, cobalt, iron etc) in and "growths" of tubes of silicate will slowly form in the solution.

metalresearcher - 17-8-2017 at 11:44

CaSO4 + aluminum powder is very powerful.
The CaSO4 is obtained from crushed plasterboard which I heated to 400 C te remove all the water and then powdered it.

I tried it yesterday. See here a video which is similar to a reversed rocket engine.

https://www.youtube.com/watch?v=HsZvbJInNCw

[Edited on 2017-8-17 by metalresearcher]

CRUSTY - 18-8-2017 at 19:58

I also do an annual demonstration for K-5 students, and although these aren't my favorites, they're quite popular among my audience:

• Nitrogen triiodide
• Flame color tests of various metal salts (I honestly hate doing this one, but they seemed to like it the year I did it)
• Oscillating iodine reaction (aka "iodine clock"; this on e gets a great reaction, especially the time I didn't get it to initiate and I told them it must not have worked, and it near instantaneously turned back to elemental iodine while my back was turned, which is apparently hilarious to elementary schoolers)
• Electroplating a quarter with copper (Dunno why that's amusing to them)
• Showing the energy in sugar by burning KNO3/Sucrose
Those are pretty consistently a hit, although I only do this once a year.

As for my favorites, ETN synthesis and other nitrations are always fun, and catalytic synthesis of formaldehyde over copper or platinum is fun too.

Morgan - 17-10-2017 at 07:48

A cute little effect. Imagine enhancing it for a toy of some sort.
"I honestly have no idea how I made this. I was just experimenting around with empty tealights and pure ethanol and suddenly it started pulsing."
https://www.youtube.com/watch?v=HxsJna3tMF4

SWIM - 17-10-2017 at 09:38

Never actually seen this one, but it was described in an old Edgar Allan Poe story and I've always wondered if it was for real. Maybe somebody here knows.

Pour sulfuric acid into a red-hot platinum crucible and after a moment add a few drops of water.

The acid is supposed to boil off so rapidly it leaves the water behind as ice which can be quickly dumped out of the crucible before it melts.

I would be very reluctant to try this even if I had a platinum crucible for reasons that must be all too obvious (water poured into hot H2SO4, H2SO4 boiling off in great clouds, etc), but has anybody else heard of this other than from Poe?

Please don't just try this unless you've seen it before or really know what you're doing. It sounds like a recipe for disaster to me and I only have the word of a long-dead mentally unstable alcoholic and opiate enthusiast that it even works. (And even if he was right, some editor might have screwed up the details as this was just part of a short story and not a report in a scientific journal)

The story was: The Thousand and Second Tale of Scheherazaad (sp?)

On re-reading that post I realized something:
Boy, that was one hell of a disclaimer, wasn't it?

Comment added several hours later:
Posting this renewed my curiosity so I checked the original Poe quote and found that he describes Sulfuric acid as, "the most volatile of bodies", which it obviously isn't.

Perhaps he was confusing sulfuric acid with sulfuric ether, an old name for diethyl ether. I suppose ether poured into a red hot crucible might briefly do that thing where it skitters around on a bed of vapor (I forget what it's called technically, but that's what it looks like), and that adding the water might result in a change in surface tension or something that would make it flash off quickly cooling the water to the freezing point.

He does refer to the vapors given off as 'sulphurous', but maybe Poe, being no chemist, just assumed sulfuric ether would boil off into sulfurous fumes of some sort.

Of course he may have just been well into his second pint of Monongahela whiskey and made the whole thing up.

[Edited on 17-10-2017 by SWIM]

[Edited on 17-10-2017 by SWIM]

NEMO-Chemistry - 17-10-2017 at 09:44

Crystal garden in water glass, drop crystals of metal salts into water glass, and watch little towers grow from seemingly very little. Plus you get the different colours, i love colbalt ones but obviously not an environmentally friendly one.

Elephant toothpaste we did, we used 12% peroxide with MnO2 (i think), and just a tiny amount of decent washing up liquid. It was done in a large measuring cylinder and shot all over the place

.

The other one i cant always get to work, is the super cold water in a bottle, (cant remember the term) then bang the bottle on a table and it freezes instantly.

super cooled water
https://www.youtube.com/watch?v=Fot3m7kyLn4
[Edited on 17-10-2017 by NEMO-Chemistry]

[Edited on 17-10-2017 by NEMO-Chemistry]

DraconicAcid - 17-10-2017 at 10:33

Quote: Originally posted by SWIM

Never actually seen this one, but it was described in an old Edgar Allan Poe story and I've always wondered if it was for real. Maybe somebody here knows.

Pour sulfuric acid into a red-hot platinum crucible and after a moment add a few drops of water.

The acid is supposed to boil off so rapidly it leaves the water behind as ice which can be quickly dumped out of the crucible before it melts.

I would be very reluctant to try this even if I had a platinum crucible for reasons that must be all too obvious (water poured into hot H2SO4, H2SO4 boiling off in great clouds, etc), but has anybody else heard of this other than from Poe?

Please don't just try this unless you've seen it before or really know what you're doing. It sounds like a recipe for disaster to me and I only have the word of a long-dead mentally unstable alcoholic and opiate enthusiast that it even works. (And even if he was right, some editor might have screwed up the details as this was just part of a short story and not a report in a scientific journal)

The story was: The Thousand and Second Tale of Scheherazaad (sp?)

On re-reading that post I realized something:
Boy, that was one hell of a disclaimer, wasn't it?

[Edited on 17-10-2017 by SWIM]

I remember reading the story, and figuring that he had no idea what he was talking about.

Morgan - 17-10-2017 at 16:07

I wonder if this property has something to do with the mystery. As an aside, the 1851 text doesn't mention sulfuric acid but rather sulfurous acid. And the boiling point of the said acid is nothing along the lines of sulfuric acid. Couple the below effect with an "insulating" Leidenfrost effect and maybe a frozen mass comes about in this way.

"When trying to concentrate the solution by evaporation to produce waterless sulfurous acid it will decompose (reversing the forming reaction). In cooling down a clathrate SO2 · 5.75 H2O will crystallise which decomposes again at 7 °C. Thus sulfurous acid H2SO3 cannot be isolated."
https://en.wikipedia.org/wiki/Sulfurous_acid

From 1851
https://books.google.com/books?id=PDFRAAAAYAAJ&pg=PA541&...

[Edited on 18-10-2017 by Morgan]

SWIM - 17-10-2017 at 16:19

Quote: Originally posted by Morgan

I wonder if this property has something to do with the mystery. As an aside, the 1851 text doesn't mention sulfuric acid but rather sulfurous acid. And the boiling point of the said acid is nothing along the lines of sulfuric acid

"When trying to concentrate the solution by evaporation to produce waterless sulfurous acid it will decompose (reversing the forming reaction). In cooling down a clathrate SO2 · 5.75 H2O will crystallise which decomposes again at 7 °C. Thus sulfurous acid H2SO3 cannot be isolated."
https://en.wikipedia.org/wiki/Sulfurous_acid

From 1851
https://books.google.com/books?id=PDFRAAAAYAAJ&pg=PA541&...

Thanks, I bet that's the answer.
Even explains the 'sulphurous vapors' line that confused me.

The version I read was probably the result of some editor who didn't know about sulfurous acid assuming it was a typo for sulfuric.

Seems like there are several versions floating around out there for many of poe's stories.

[Edited on 18-10-2017 by SWIM]

Morgan - 17-10-2017 at 17:12

Near the bottom of the page
"*(5) Place a platina crucible over a spirit lamp, and keep it a red heat; pour in some sulphuric acid, which, though the most volatile of bodies at a common temperature, will be found to become completely fixed in a hot crucible, and not a drop evaporates- being surrounded by an atmosphere of its own, it does not, in fact, touch the sides. A few drops of water are now introduced, when the acid, immediately coming in contact with the heated sides of the crucible, flies off in sulphurous acid vapor, and so rapid is its progress, that the caloric of the water passes off with it, which falls a lump of ice to the bottom; by taking advantage of the moment before it is allowed to remelt, it may be turned out a lump of ice from a red-hot vessel."
http://xroads.virginia.edu/~hyper/poe/shehera.html

Summary
https://en.wikipedia.org/wiki/The_Thousand-and-Second_Tale_o...

Melgar - 18-10-2017 at 03:27

Sounds like he could be describing SO3 when he's talking about "sulfurous acid". After all, it's boiling point is what? 45C? This is all pre-IUPAC naming conventions of course, when both pure substances and mixtures could have any of a number of overlapping common names. I could certainly imagine hot SO3 reacting violently when coming in contact with a few drops of water.

SWIM - 18-10-2017 at 08:46

Quote: Originally posted by Melgar

Sounds like he could be describing SO3 when he's talking about "sulfurous acid". After all, it's boiling point is what? 45C? This is all pre-IUPAC naming conventions of course, when both pure substances and mixtures could have any of a number of overlapping common names. I could certainly imagine hot SO3 reacting violently when coming in contact with a few drops of water.

I did wonder about that possibility too, but I had a hard time coming up with a way that that would produce ice. Seems to me the result would more probably be best described as a cloud of agony. Not as bad as the Nazis opening the Ark Of The Covenant in Raiders Of The Lost Ark, but still pretty nasty.

Hell, I've really derailed this thread, sorry. Maybe this Poe stuff should be split off and put somewhere more appropriate.

Melgar - 18-10-2017 at 10:10

Quote: Originally posted by SWIM

Could be sulfuric acid ice. That is, the SO3 is superheated, water is added, which not only adds heat, but messes up the whole superheating phenomenon. All the SO3 boils away at once, removing enough heat from the system to freeze the fraction of the SO3 that has been turned into H2SO4 by the water.

It's weird hearing it described in terms that aren't what anyone would use today, but that seems to be a good contender.

LearnedAmateur - 19-10-2017 at 09:16

Nitrogen triiodide has to be one of my favourite demonstrations. A tiny amount of solid that can detonate simply by dropping a feather on it, releasing a vast purple cloud of iodine vapour. Also along those lines, watching the direct deposition of iodine vapour is also cool. To a beaker is placed a gram or so of iodine and on top, a round bottom flask filled with ice cold water is placed. The iodine is heated so it sublimes, and as it comes into contact with the flask, 'hairs' of crystalline iodine form - this can also be done on a smaller scale using a test tube and boiling tube (image attached). This is also a great way to purify iodine.

[Edited on 19-10-2017 by LearnedAmateur]

NEMO-Chemistry - 19-10-2017 at 20:58

I found a nice demonstration that might be interesting, i intend doing the experiment this weekend. The experiment is from JCE, it uses magnetized bio char to remove Salicylic Acid and 4-Nitroaniline from water. However it might work at removing a food dye instead.

Sounds boring but basically you add the biochar to the coloured water, then use a magnet to remove the biochar and colour from the water.

The reference is
Karunanayake, A. G. et al. (2016) ‘Salicylic Acid and 4-Nitroaniline Removal from Water Using Magnetic Biochar: An Environmental and Analytical Experiment for the Undergraduate Laboratory’, Journal of Chemical Education, 93(11), pp. 1935–1938. doi: 10.1021/acs.jchemed.6b00154.

Might be neat if you can remove say blue dye from water with a magnet and should be cheap.

[Edited on 20-10-2017 by NEMO-Chemistry]

Morgan - 31-1-2018 at 09:18

Bird defeats Einstein
The Engineering of the Drinking Bird
https://www.youtube.com/watch?v=UCKC-QVcVn0

Sulaiman - 31-1-2018 at 10:15

Quote: Originally posted by Morgan

A cute little effect. Imagine enhancing it for a toy of some sort.
"I honestly have no idea how I made this. I was just experimenting around with empty tealights and pure ethanol and suddenly it started pulsing."
https://www.youtube.com/watch?v=HxsJna3tMF4

Congratulations ...you just re-invented https://en.wikipedia.org/wiki/Pulse_detonation_engine

may be a good one to send to the SloMoGuys ?

j_sum1 - 31-1-2018 at 14:12

Quote: Originally posted by Morgan

Bird defeats Einstein
The Engineering of the Drinking Bird
https://www.youtube.com/watch?v=UCKC-QVcVn0

Yay! Someone else is subscribed to engineerguy.
I like his stuff.

Morgan - 31-1-2018 at 15:16

Quote: Originally posted by j_sum1

Quote: Originally posted by Morgan

Bird defeats Einstein
The Engineering of the Drinking Bird
https://www.youtube.com/watch?v=UCKC-QVcVn0

Yay! Someone else is subscribed to engineerguy.
I like his stuff.

Related subject matter maybe of interest ...

"I used ordinary acetone as the working fluid. I also made some "bubblers" that worked at room temperature using evaporative cooling at the top end.
http://nfttu.blogspot.com/2009/04/methylene-chloride-and-dip...

Some sort of something here
https://www.youtube.com/watch?v=b9JFr6pEJco

Vomaturge - 2-2-2018 at 01:46

Potassium permanganate and glycerin, water boiling at room temperature and reduced pressure, hydrogen balloons filled using aluminum and sodium hydroxide.

Morgan - 28-11-2019 at 15:55

Here's an apropos jam jar jet demonstration for the chemistry crowd or stress testing the borosilicate glass.

Erlenmeyer Flask Jam Jar Jet Snorkeler
https://www.youtube.com/watch?v=mDrdUy-LWHY

[Edited on 28-11-2019 by Morgan]

Musical Flames and other excerpts

Morgan - 2-2-2021 at 13:12

From the physicist John Tyndall's book "Sound" in the 1800's.
A long tube in the verticle ...

Fig. 114. Fig. 114.A still more striking effect is obtained with this larger tube, a b, Fig. 114, 15 feet long and 4 inches wide, which was made for a totally different purpose. It is supported by a steady stand, s s′, and into it is lifted the tall burner, shown enlarged at B. You hear the incipient flutter: you now hear the more powerful sound. As the flame is lifted higher the action becomes more violent, until finally a storm of music issues from the tube. And now all has suddenly ceased; the reaction of its own pulses upon the flame has beaten it into extinction. I relight the flame and make it very small. When raised within the tube, the flame again sings, but it is one of the harmonics of the tube that you now hear. On turning the gas fully on, the note ceases—all is silent for a moment; but the storm is brewing, and soon it bursts forth, as at first in a kind of hurricane of sound. By lowering the flame the fundamental note is abolished, and now you hear the first harmonic of the tube. Making the flame still smaller, the first harmonic disappears, and the second is heard. Your ears being disciplined to the apprehension of these sounds, I turn the gas once more fully on. Mingling with the deepest note you notice the harmonics, as if struggling to be heard amid the general uproar of the flame. With a large Bunsen’s rose burner, the sound of this tube becomes powerful enough to shake the floor and seats, and the large audience that occupies the seats of this room, while the extinction of the flame, by the reaction of the Fig. 115. Fig. 115.sonorous pulses, announces itself by an explosion almost as loud as a pistol-shot. It must occur to you that a chimney is a tube of this kind upon a large scale, and that the roar of a flame in a chimney is simply a rough attempt at music.

The action reminds one of the story of the Swiss muleteers, who are said to tie up their bells at certain places lest the tinkle should bring an avalanche down. The snow must be very delicately poised before this could occur. It probably never did occur, but our flame illustrates the principle. We bring it to the verge of falling, and the sonorous pulses precipitate what was already imminent. This is the simple philosophy of all these sensitive flames.

A flame of astonishing sensitiveness now burns before you. It issues from the single orifice of a steatite burner, and reaches a height of 24 inches. The slightest tap on a distant anvil reduces its height to 7 inches. When a bunch of keys is shaken the flame is violently agitated, and emits a loud roar. The dropping of a sixpence into a hand already containing coin, at a distance of 20 yards, knocks the flame down. It is not possible to walk across the floor without agitating the flame. The creaking of boots sets it in violent commotion. The crumpling, or tearing of paper, or the rustle of a silk dress, does the same. It is startled by the patter of a rain-drop. I hold a watch near the flame: nobody hears its ticks; but you all see their effect upon the flame. At every tick it falls and roars. The winding up of the watch also produces tumult. The twitter of a distant sparrow shakes the flame; the note of a cricket would do the same. A chirrup from a distance of 30 yards causes it to fall and roar.

At a distance of 30 yards, for example, the chirrup of a house-sparrow would be competent to throw the flame into commotion.

Curved roofs and ceilings and bellying sails act as mirrors upon sound. In our old laboratory, for example, the singing of a kettle seemed, in certain positions, to come, not from the fire on which it was placed, but from the ceiling. Inconvenient secrets have been thus revealed, an instance of which has been cited by Sir John Herschel.16 In one of the cathedrals in Sicily the confessional was so placed that the whispers of the penitents were reflected by the curved roof, and brought to a focus at a distant part of the edifice. The focus was discovered by accident, and for some time the person who discovered it took pleasure in hearing, and in bringing his friends to hear, utterances intended for the priest alone. One day, it is said, his own wife occupied the penitential stool, and both he and his friends were thus made acquainted with secrets which were the reverse of amusing to one of the party.

The celebrated French philosopher, Biot, observed the transmission of sound through the empty water-pipes of Paris, and found that he could hold a conversation in a low voice through an iron tube 3,120 feet in length. The lowest possible whisper, indeed, could be heard at this distance, while the firing of a pistol into one end of the tube quenched a lighted candle at the other.

[Edited on 2-2-2021 by Morgan]

Morgan - 24-2-2021 at 11:29

Quote: Originally posted by Morgan

Yesterday I was toying with a pale yellow mushroom that forms a sack with a goodly amount of spores inside, the kind that billow a lot of smokey spores when popped. The mushroom wasn't some perfectly round kind you sometimes see but an odd very light weight, pale yellow and brown, elongated bumpy membrane somewhat egg-shaped and it didn't seem to have an pronounced attachment point where it rooted to the ground. So the thought was to see how the spores might burn if held next to a lit Bic lighter.
Surprisingly, when the partially split sac of spores was compressed near a flame the fireball the burning spores made was quite perky, reminiscent of lycopodium powder. So if you had a large amount of these which were collected for their spores, perhaps they'd be a comparable/alternative "dragon's breath" source, slightly quirky or road less traveled.

I wonder if you had someone standing by with a lit propane torch if this puffball spore cloud would burst into flames?
https://www.youtube.com/watch?v=5TeFsg9e-ks

Update
Researching Astraeus hygrometricus recently perhaps it's spores would work as well as lycopodium for some effects if you could gather enough of them. I bought a couple of 3 ounce bottles of lycopodium spores a few years ago, which is fairly bulky like powdered charcoal but not all that inexpensive.
https://youtu.be/rXGy2KjefDw

[Edited on 24-2-2021 by Morgan]

Piroz - 24-2-2021 at 13:35

Burning various compounds in stream of oxygen is nice experiment, I tried this few years ago with some chemicals: sulfur, titanum, aluminium, magnesium, iron, charcoal, wood and sugar:

https://youtu.be/lYtUHB1LtfY

Other amazing experiment that I tried is spectacular autoignition of finely powdered zinc with ammonium nitrate with some ammonium chloride. After add a drop of water it "explodes" with greenish- blue flame:

https://youtu.be/uYjyH1ZQXdI

[Edited on 24-2-2021 by Piroz]

Morgan - 9-4-2021 at 07:29

Here's a clever variation on a theme. Sometimes you see a sleeve over the tube to modulate the pitch like a trombone, but this was amusing.
The world first blowless flute - I play a melody on my thermoacoustic engine
https://youtu.be/Qqk36IZqIgY

Another more basic variant
Singing Test Tubes
https://youtu.be/iN2P6KU9bEg

I was wondering if a battery driven tiny piezo speaker/tone generator placed inside a tube with holes at the end could be played as musical instrument in a band for novelty. It would be funny to see a flute-like instrument but without the need to have it near your mouth or constricted by having a flame tied to it, walking around while you played it.

[Edited on 9-4-2021 by Morgan]

ChemichaelRXN - 9-4-2021 at 10:24

Oil and vinegar

No just kidding...

I liked the video by ChemicalForce where he mixed carbon disulfide and Potassium superoxide. It explodes like it was a high explosive almost. (I dont deal with explosives...laws etc. I just watch youtube)

Morgan - 17-4-2021 at 07:48

I saw this repurposed device that might be handy for some demonstrations. There're some for less than $20.00 on ebay.

Mini Handheld Tesla Coil(Oudin Coil
https://youtu.be/x0QmomYHt_I

Say for things like this or whatever creative use you might think of.
Volta's Pistole,Volta's Pistol
https://youtu.be/WZerYRGU33c

Methanol Cannon
https://youtu.be/Wn5wr9ZAq3s

Morgan - 17-10-2021 at 11:13

Quote: Originally posted by Morgan

Yesterday I was toying with a pale yellow mushroom that forms a sack with a goodly amount of spores inside, the kind that billow a lot of smokey spores when popped. The mushroom wasn't some perfectly round kind you sometimes see but an odd very light weight, pale yellow and brown, elongated bumpy membrane somewhat egg-shaped and it didn't seem to have an pronounced attachment point where it rooted to the ground. So the thought was to see how the spores might burn if held next to a lit Bic lighter.
Surprisingly, when the partially split sac of spores was compressed near a flame the fireball the burning spores made was quite perky, reminiscent of lycopodium powder. So if you had a large amount of these which were collected for their spores, perhaps they'd be a comparable/alternative "dragon's breath" source, slightly quirky or road less traveled.

I wonder if you had someone standing by with a lit propane torch if this puffball spore cloud would burst into flames?
https://www.youtube.com/watch?v=5TeFsg9e-ks

After looking over some photos I think it's possible that the mushroom I found was an earthstar as there were a few dozen banana peel looking things in my lawn that came after some rains. If you look at the 3rd photo that's sort of what my flammable spore ball looked like but more of a potato shape without the perfect round shape with a pointy top.
http://www.realmonstrosities.com/2013/06/earthstar.html
Or it could have been something like this poisonous earthball.
http://www.wildutah.us/html/plants_scenery/h_mushroom_earthb...

[Edited on 31-1-2017 by Morgan]

Having thought puffball spores might make a good substitute for a lycopodium dragon"s breath demo it seems if you worked with the spores a lot or were more allergic than most people for some reason, maybe there could be a slight risk to your health. In the above, there's a guy who runs over a giant puffball with his mower creating a big cloud of spores.

"In one particularly unfortunate case, a group of eight apparently sober teenagers decided it would be a good idea to inhale the spores squeezed from some puffballs they had acquired. After a couple of days, they started to cough, had trouble breathing, ran a fever, and felt generally crappy. Things got so bad that five of the teens were hospitalized, two of them needing to be intubated to help them breathe. Their inflamed lungs were treated with corticosteroids and they all eventually recovered from their illness."

"Lycoperdonosis has also been seen in people who snorted puffball spores as a folk remedy for a nosebleed. Both puffballs and earthstars have killed or seriously injured dogs who disturbed them and inhaled their spores as they ran about or dug holes."
http://www.rosincerate.com/2016/03/how-bacteria-and-fungi-ca...

It seems even lycopodium can be hazardous in some cases.
https://www.sciencedirect.com/topics/pharmacology-toxicology...

[Edited on 18-10-2021 by Morgan]

Plunkett - 17-10-2021 at 14:53

This demonstration is more material science than chemistry, but you take a length of music wire (high carbon steel) and stretch it between two ring stands. Then you pass an electric current through the wire causing it to heat up. As the wire heats up it starts to sag from thermal expansion, but when the wire hits the austenite transition temperature the wire lifts slightly as the body-centered cubic ferrite in the steel is converted to the more densely packed face-centered cubic austenite causing the wire to contract. The wire then starts to sag again as the temperature is increased. The effect is more pronounced in reverse when the wire contracts as it cools, then sags at the phase transition temperature, and contracts as it cools further.
https://youtu.be/W6Pa4n4Abyw

karolus28 - 20-10-2021 at 11:10

maybe not a demonstration but If you mix some glycerol with potassium chlorate and ignite, it burns for a bit and when hot enough it goes うじゅうぅぅ〜〜ん! Big flame upwards - I think it's pretty cool

Morgan - 17-4-2022 at 14:44

Maybe not much chemistry, but some pressure, volume, and temperature gas laws and heat transfer going on. Anyway, just a very simple external combustion toy using a couple of test tubes in a tube. I was initially using the bottom tube to take up volume but found it moved if upturned.
https://youtu.be/EosXGSEvkuU
https://youtu.be/trCiuU69YcE

SWIM - 17-4-2022 at 21:38

If those puffball snorters are the ones I'm thinking about, they thought the puffballs were hallucinogenic.

There were some erroneous reports of puffballs that produced auditory hallucinations in some old popular books on hallucinogens from the 60s or 70s.

I think Schultes may have been involved in these reports but am unsure and don't want to blame a guy who generally did great work. I think they were the species marginata.

The reports weren't about snorting spores, but puffballs are often found when over-ripe, and at that stage they're not like tasty mushrooms but like little leathery sacks of spores.

Edit: I see Dave Aurora believes these reports, but I'm pretty sure they've been discredited. (But If you want to learn US mushrooms Aurora's mushrooms demystified is a great book.)

[Edited on 18-4-2022 by SWIM]

Morgan - 15-2-2023 at 11:03

This is more of a physics demo category, but the way a small sealed volume of heated air can shuttle about was curious to observe. It's just some steel wool and a silicone breast milk pump diaphragm in a clear quartz crucible and then sleeved to a silicone milk bottle cap held to a Euler's disk with a small flat magnet. Maybe of interest.

Stirling Jumper Sounding Like a Euler's Disk When Stopping
https://youtu.be/KfbRd5LtIxc

PS I wonder if there's a way to tell how many Hz it's cycling at just using the sound?

[Edited on 15-2-2023 by Morgan]

Jeeves225 - 16-2-2023 at 04:29

A visually pleasing demonstration I really like is the separation of dyes using column chromatography.

Morgan - 18-2-2023 at 14:29

Here's a pretty simple engine that doesn't take much time to make.

Easy Balloon Three Piece Stirling Hot Air Jumper
https://youtu.be/B547cKwERzI

And a souped-up version. At the 1:14 mark it appears stretched and motionless for a couple of seconds.
https://youtu.be/ciHfynKzFE0

[Edited on 19-2-2023 by Morgan]

Dr.Bob - 18-2-2023 at 19:39

I like the chemistry demos using black powder, fuel, oxidants, and various metals salts organixed into sphers or cylinders, being ignited while in a tight fitting tube. Great way to demonstrate atomic emission spectroscopy, along with redox chemistry and the production of auditory energy from chemicals.

Morgan - 3-12-2023 at 19:48

Trevelyan's Wieger,Wackler,Rocker,Instrument
https://www.youtube.com/watch?v=U23iwbVX-Dk

Trevelyan Rocker
https://www.youtube.com/watch?v=D51nazEkutE

The article is fairly extensive, the various metals, properties and variations that were tried and the accounts of this discovery by Trevelyan and a few others were interesting as they worked to understand the effect.

"In the year 1829 Mr. Arthur Trevelyan was engaged in spreading pitch with a
hot plastering iron, and observing in one instance that the iron was too hot, he laid it slantingly against a block of lead which happened to be at hand. Shortly afterwards he heard a shrill note, resembling that produced on the chanter of the smaller Northumberland pipes, an instrument played by his father’s gamekeeper. Not knowing the cause of the sound he thought that this person might be practising out of doors, but on going out the tone ceased to be heard, while on his return he heard it as shrill as before. His attention was at length attracted to the hot iron, which he found to be in a state of vibration, and thus discovered the origin of this strange music."

After seeing an above video, I gave it a try with a "design" that I arrived at using stuff that I had, trying several things until something worked. Later I found the silver coin would rev up from a standstill, you don't have to start it moving.
Trevelyan Rocker with a Silver Dollar and Stainless Steel
https://www.youtube.com/watch?v=7wzM4iSZyWE

On the Vibrations and Tones produced by the Contact of Bodies having different Temperatures.
https://royalsocietypublishing.org/doi/pdf/10.1098/rstl.1854...

Mechanical Analysis of the Trevelyan Rocker
https://www.nature.com/articles/017242f0

"One of these lead blocks is kept in the refrigerator as the greater the difference in temperature between the block and the rocker the better it works. Another interesting note is that the frequency of the rocker will not descend steadily, but will jump from one harmonic to another."
https://instructional-resources.physics.uiowa.edu/demos/4a30...

The Theory of the Trevelyan Rocker
https://www.tandfonline.com/doi/abs/10.1080/1478644230863631...

[Edited on 4-12-2023 by Morgan]

knowledgevschaos - 4-12-2023 at 01:01

A crystal of potassium chlorate, with a bit of sulfur, wrapped in aluminium foil and hit with a hammer can be a fun demonstration.

Morgan - 11-12-2023 at 17:00

Another variation on the Trevelyan Rocker using a piece of 1/2 inch plumbing pipe. It's just strange to watch with no apparent interaction of the metal surfaces to cause motion on the scale visible to the eye.
Trevelyan Rocker Shower Arm
https://www.youtube.com/watch?v=pyFmHYx8Aik

[Edited on 12-12-2023 by Morgan]

Morgan - 12-12-2023 at 11:09

A coin vibrating making a fair amount of sound. It's interesting from the perspective of the properties of metals, the heat capacity, thermal expansion, thermal conductivity, etc. Around the 1:30 second mark it makes a steady humming sound building feedback in the stainless steel tray.

Trevelyan Rocker High Pitch Resonance with a Kennedy Fifty Cent Piece
https://www.youtube.com/watch?v=7InFwKHOi38

Morgan - 17-12-2023 at 16:12

Thought is copper-magnesium alloy was mildly interesting.

Tim's Amazing Yi Bell
https://www.youtube.com/watch?v=id-u9ro50TM

"The Yi bell is used to demonstrate the relationship between temperature and oscillation damping."
https://www.a3bs.com/product-manual/U30002_EN.pdf

Copper-magnesium eutectic as phase change material for thermal storage applications: Thermophysical properties and compatibility
https://www.sciencedirect.com/science/article/abs/pii/S23521...

[Edited on 18-12-2023 by Morgan]

Morgan - 27-12-2023 at 07:02

An easy to make arrangement for this subject.

"After delivering an authoritative Friday Evening Lecture in the summer of 1853, the Royal Institution offered Tyndall its prestigious chair in natural philosophy, which he held until 1887. Michael Faraday had been influential in this appointment, being impressed with Tyndall’s experimental knowledge and practices, and they collaborated at the Royal Institution until Faraday’s death in 1867. 21 The topic of Tyndall’s career-establishing Friday Evening Lecture had been an acoustic one, examining the sounds produced through heated metals, which Trevelyan, Faraday, and Forbes had investigated during the 1830s."
https://academic.oup.com/chicago-scholarship-online/book/425...

Eye Nut Trevelyan Rocker
https://www.youtube.com/watch?v=Lgc4HgylHJU
1 2 3 Block Springs to Life as a Trevelyan Rocker
https://www.youtube.com/watch?v=eq2KY3BqCv0

Morgan - 30-12-2023 at 18:08

Quote: Originally posted by Morgan

Thought is copper-magnesium alloy was mildly interesting.

Tim's Amazing Yi Bell
https://www.youtube.com/watch?v=id-u9ro50TM

"The Yi bell is used to demonstrate the relationship between temperature and oscillation damping."
https://www.a3bs.com/product-manual/U30002_EN.pdf

Copper-magnesium eutectic as phase change material for thermal storage applications: Thermophysical properties and compatibility
https://www.sciencedirect.com/science/article/abs/pii/S23521...

[Edited on 18-12-2023 by Morgan]

Perhaps this would add to the above demonstrations if a Tibetan cymbal were heated too.

Tibetan Tingsha Cymbals Versus Temperature
https://www.youtube.com/watch?v=4SOyVX4r3MA

wg48temp9 - 1-1-2024 at 05:31

The Trevelyan Rocker reminds of a curious effect with steel ball bearings. If an electric current is passed between the inner race and the outer race via the balls the races will rotate wrt each other after an initial push to get them going.

See: https://www.acorn-ind.co.uk/insight/just-for-fun-the-ball-be...

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