Difference between revisions of "Chemical demonstrations"
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==Alkali metals== | ==Alkali metals== | ||
===In the presence of water=== | ===In the presence of water=== | ||
| − | [[Lithium]] will effervesce strongly | + | [[Lithium]] will effervesce strongly and may ignite; |
| − | [[Sodium]] will do so more strongly and | + | [[Sodium]] will do so more strongly and more often than not catches fire, potentially exploding when in large amounts; |
| − | [[Potassium]] catches fire | + | [[Potassium]] catches fire and almost always explodes; |
| − | [[Rubidium]] and [[caesium]] will explode. | + | [[Rubidium]] and [[caesium]] will explode unless added in tiny amounts. |
[https://www.youtube.com/watch?v=uixxJtJPVXk Video: Alkali metals reaction with water] | [https://www.youtube.com/watch?v=uixxJtJPVXk Video: Alkali metals reaction with water] | ||
Latest revision as of 20:04, 16 October 2022
Chemical demonstrations that are amusing or impressive to watch.
Contents
Energetic materials
Explosive decomposition of Para-nitroaniline
Para-nitroaniline explodes, leaving an impressive mount of carbon behind under the attack of hot concentrated sulfuric acid.
Video: P-nitroaniline's decomposition demonstration
Mercury thiocyanate ("Pharaoh's serpent")
Mercury(II) thiocyanate burns forming residues looking like tentacles growing from the ground.
Video: mercury thiocyanate's combustion demonstration
Ammonium dichromate ("Volcano")
When ammonium dichromate burns, it looks like an erupting volcano.
Video: ammonium dichromate's combustion demonstration
Iodine and aluminium
When aluminium and iodine are combined in the presence of a small amount of water, they react to produce thick purple smoke and leaves a metallic coating on the glass.
Video: Iodine and aluminium demonstration
Color changes
Briggs-Rauscher oscillator
Very pronounced and rapid color changes repeating again and again and again.
Video: iodine oscillator demonstration
Iodine clock reaction
Colorless solutions becoming deep blue/black almost instantaniously after a small delay.
video: iodine clock demonstration and theory
Chameleon
5 vivid color changes in a row while the reaction passes through the many different oxidation states of manganese.
Video: Chameleon demonstration
Light emission
Fluorescent pH indicator
Pyranine, present in highlighter fluid, will fluoresce different colors in different levels of acidity.
Smash-glow crystals
Sugar will emit ultraviolet light when crushed. When a fluorescent dye such as methyl salicylate is used, the fluorescence is made much brighter.
Miscellaneous
Elephant toothpaste
The rapid decomposition of hydrogen peroxide with a catalyst (usually potassium iodide or yeast) in soapy water generates a huge amount of hot foam due to oxygen generation.
Video: Elephant toothpaste demonstration
Carbon snake
Materials needed: granular sugar and concentrated (98%) sulfuric acid, acid resistant gloves
Procedure: Pour concentrated sulfuric acid directly onto sugar.
Result: a tower of porous carbon forms after a delay period.
Video: carbon snake demonstration
Alkali metals
In the presence of water
Lithium will effervesce strongly and may ignite;
Sodium will do so more strongly and more often than not catches fire, potentially exploding when in large amounts;
Potassium catches fire and almost always explodes;
Rubidium and caesium will explode unless added in tiny amounts.
Video: Alkali metals reaction with water
