Continuing my experimentation with bismuth

AI Thread Summary
Bismuth exhibits intriguing properties, particularly its colorful oxides that appear only when the metal is hot and exposed to air. A user polished a bismuth sample with a scouring cream, revealing its shiny, silvery appearance without oxidation, even after contact with air and moisture. This contrasts with its rapid tarnishing when molten. The discussion highlights the role of heat in chemical reactions, clarifying that while both heat and catalysts speed up reactions, they do so through different mechanisms. Additionally, bismuth's unique density properties were noted, as solid bismuth floats on its molten form, and its weak diamagnetism was mentioned, showcasing its repulsion in a magnetic field. The user expressed a desire to maintain the bismuth's luster over time and shared experiences of experimenting with its properties, including the challenges faced during melting.
BetaZeta2016
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The more i study this strange element, the more interesting it becomes.

I found that bismuth only shows it's colorful oxides when exposed to air while hot/molten.

I decided to go outside and polish the sample using an abrasive liquid known in Brazil as "Saponáceo Cremoso".
Don't know what it's called in english-speaking countries.

Edit: It's called "Scouring cream" in english.

Anyway, it's used to polish aluminum cookware as well as any other metal surfaces.

So i took my bismuth sample out and started polishing.

The metal finally showed it's natural appearance: A lustrous, shiny and silvery material that resembles lead or iron.

But something more happened: It didn't oxidize. Even after being exposed to air, water or even the oils from my hand, it's still shiny, without any noticeable color change.

But when molten, it tarnishes instantaneously!

Anyone knows why?
 
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BetaZeta2016 said:
So the heat acts as a catalyst here.

No. Catalyst is a catalyst, heat is a heat. Both speed up the reaction, but for completely different reasons.
 
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Borek said:
No. Catalyst is a catalyst, heat is a heat. Both speed up the reaction, but for completely different reasons.

Oh, nice. Thank you for clarifying :smile:.
 
As you were melting Bismuth and already messing up one pan: Did you observe the solid bismuth to float on the melt? Bismuth is one of the few substances (like water) where the solid is less dense than the melt.
 
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DrDu said:
As you were melting Bismuth and already messing up one pan: Did you observe the solid bismuth to float on the melt? Bismuth is one of the few substances (like water) where the solid is less dense than the melt.

Yes, i did!
While the bismuth was molten, there was a small chunk floating on the top of the liquid.

I won't do it on the kitchen again. One pan just went to the trash because of this hehe. :biggrin:
 
Bismuth is also a relatively strongly diamagnetic substance, i.e. it gets repelled by a magnetic field. If you mount your probe on a string and bring a strong magnet close (best one of these small neodymium magnets) it will turn away.
 
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Cool experiment too! I tried it with some magnets from old hard drives.

Bismuth diamagnetism is very weak.
But still stronger than any other material i have ever seen.
 
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