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

I want to hear your favorite chemistry demonstrations

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Morgan - 1-1-2024 at 12:45

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...

Yes, that thought came to mind when I first started toying with Trevelyan Rockers. Also this effect as if such a surface might propel a hot bearing ball, in order for it to rock/teeter along in one direction.
https://www.gyroscope.com/d.asp?product=LEIDENFROSTRING
https://www.youtube.com/watch?v=mVhwiQO16VI

[Edited on 2-1-2024 by Morgan]

Morgan - 21-1-2024 at 17:43

From the 1800's, this lecture with illustrations brings to mind the bearing ball motor whatever the case is with that motor.

"Mr. Gore has also obtained the rotation of light balls, by placing them on circular rails of hot copper, the rolling force in this case being the same as the rocking force in the Trevelyan instrument."

A video following his idea.
Tyndall's Heat Considered as a Mode of Motion
https://www.youtube.com/watch?v=2u6yTjKzGpM

As an aside ...
Slow Acceleration of the Trevelyan Rocker Effect
https://www.youtube.com/watch?v=C31kqFgWjjk

6061 Bar Stock Thermal Resonant Feedback
https://www.youtube.com/watch?v=UryWnalrtO0

[Edited on 22-1-2024 by Morgan]

Morgan - 26-1-2024 at 11:29

More on the exploration of the ball bearing motor subject matter trying to see if heat alone could compete with the electromagnetism theory - whether one or the other or both.
Little Wheel Motor or Trevelyan Rocker Roulette
https://www.youtube.com/watch?v=9jKUXVG8duE

[Edited on 26-1-2024 by Morgan]

Morgan - 9-2-2024 at 14:56

The ongoing saga this time with a revolving brass sphere.
A Single Brass Ball Bearing Motor
https://www.youtube.com/watch?v=Se1hlK7twzc

Morgan - 22-2-2024 at 12:30

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

Morgan - 23-2-2024 at 05:56

Another alloy with the hot versus cold metal ringing effect, here discovered searching for a material for a nose cone reentry material.
The Metal That Remembers - Nitinol
https://www.youtube.com/watch?v=0xT2du855mQ&t=79s

Would any rocket scientists know the reason/clarify why ringing would be a desired property of a metal for the nose cone example? Could it be something indicating the metals mixed well?

[Edited on 23-2-2024 by Morgan]

averageaussie - 29-2-2024 at 15:40

Quote: Originally posted by Morgan

Another alloy with the hot versus cold metal ringing effect, here discovered searching for a material for a nose cone reentry material.
The Metal That Remembers - Nitinol
https://www.youtube.com/watch?v=0xT2du855mQ&t=79s

Would any rocket scientists know the reason/clarify why ringing would be a desired property of a metal for the nose cone example? Could it be something indicating the metals mixed well?

[Edited on 23-2-2024 by Morgan]

The ability for nitinol to remember its shape has something to do with crystal structure, and the deformation of it. metal ringing, called a metal cry or twining, also has something to do with crystal structure and the deformation of it.

Morgan - 1-3-2024 at 08:39

Quote: Originally posted by Morgan

Morgan - 1-3-2024 at 08:39

Quote: Originally posted by Morgan

Perhaps homogeneous mixing was one aspect

"Hoping to hear a clear bell-like ring, indicating that the metal had the properties he was hoping for. Instead, it returned a dull thud–similar to dropping a sack of flour on the ground. Worried that the ingot was filled with internal flaws, he dropped one of the ingots that hadn’t cooled yet. This returned a wonderful bell-like ring. However, after the ingot had been cooled in water, it returned a dull, leaden thud, just like the first one. This is the first indication that nitinol had a substantially different double state. Buehler named his alloy nitinol for Nickel-Titanium Naval Ordinance Laboratories"

Gleaned from a viewer comment on this video
https://www.youtube.com/watch?v=8-dCIkJAjyM

Tangent on ringing rocks, maybe of interest ...
"The iron content of the diabase is often identified as the source of the ringing ability. Actual chemical analysis of the Coffman Hill diabase[13] shows that iron content (as ferric oxide) of the rock ranges from 9% and 12%. Although comparatively high for an average igneous rock (3% is typical for granite), it is within the normal range for a basalt. This point suggests that the iron content is not a primary factor in the ringing ability."
https://en.wikipedia.org/wiki/Ringing_rocks

Ringing Rocks Park Bucks County PA
https://www.youtube.com/watch?v=fBiVt1pKnAQ

[Edited on 1-3-2024 by Morgan]

Morgan - 4-3-2024 at 04:36

Perhaps not all that enthralling, but this simple demonstration was an interesting phase change effect.

"Can you hear that?"
How NASA Reinvented The Wheel
https://www.youtube.com/watch?v=vSNtifE0Z2Q&t=900s

Morgan - 12-3-2025 at 17:03

This flask burning methanol was kind of a lively chemistry demonstration of combustion.
Kimax Volumetric Flask Jam Jar Jet Snorkeler
https://www.youtube.com/watch?v=R9GTEybNcQQ

moviez - 12-3-2025 at 20:42

For a more general audience, colored flame is such a visually striking demonstration. All we need is methanol, acetone and several inorganic compounds. See a picture below!

Red: methanol +Lithium nitrate (other lithium salt should work too)
Orange: methanol + calcium chloride
Yellow: acetone
Green: methanol +boric acid
Blue: methanol + copper sulfate
Violet: methanol + potassium chloride

For more science oriented minds, BZ reaction is the way to go. The color change is quite dramatic, and they oscillate, too. Plenty of YouTube videos explains how to do this (some videos in my channel too).

I did both of them with my family a few times and everyone loved it.

moviez - 12-3-2025 at 20:45

Here is the picture of the colored flame demonstration

Quote: Originally posted by SAACS

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?

[Edited on 13-3-2025 by moviez]

Mateo_swe - 17-3-2025 at 05:38

On TV channel Discovery science they do a chemical demonstration as advertising for the channel.
It´s a white powder they set on fire on a stone slab and it expands and rises a black/green snakelike formation.

Looks somewhat like some nitrate/sugar mix when it burns but it must be something else.
Anybody know what this demonstration is and what chemicals they use?

Cathoderay - 17-3-2025 at 06:06

That sounds like Pharaoh's Serpent (mercury thiocyanate).
https://www.youtube.com/watch?v=PSDpgBOtSNY

A very old demonstration, but poisonous.
You need very good ventilation!

Mateo_swe - 18-3-2025 at 04:36

Yes, thats looks very similar.
Only the colors are different, Nilered variant is brown/yellow and the science channel has a black/green snake.
It´s unfortunate that the chemicals used is so poisonous.
Maybee there is some variations of this demonstration with less toxic chemicals and other colors.
I search a bit to see what i can find.

Cathoderay - 18-3-2025 at 06:36

I also found this. Maybe what you saw was a "Sugar Snake".
https://en.wikipedia.org/wiki/Black_snake_(firework)

Mateo_swe - 20-3-2025 at 07:44

Well it looks like Pharaoh's Serpent demonstration.
But a very similar experiment can be done without the mercury by using just soda and sugar (and some similar variants exists).
But it seems the original mercury thiocyanate variant is a bit more spectacular and vigourous.
Strange that the most impressive stuff also has to be the most dangerous, maybe it´s just how life works.

Morgan - 24-3-2025 at 11:17

Maybe of interest
The amazing properties of glass-ceramics
https://www.youtube.com/watch?v=qi8jmEbWsxU

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