Chemistry demonstrations can capture a student's attention and spark an enduring interest in the science. Here's a look at some noteworthy chemistry demos.
Mix metal salts in alcohol. Spritz the liquid onto a flame to change its color. This is a great introduction to the study of emission spectra and flame tests. The colorants are of low toxicity, so this is also a safe demonstration.
Mixing sulfuric acid with sugar is simple, yet spectacular. The highly exothermic reaction produces a steaming black column that pushes itself up from the beaker. This demonstration can be used to illustration exothermic, dehydration, and elimination reactions.
If you breathe sulfur hexafluoride and talk, your voice will be very low. If you breathe helium and talk, your voice will be high and squeaky. This safe demonstration is easy to perform.
Keith Weller, USDA
This simple demonstration can be used to introduce cryogenics and phase changes. The resulting ice cream tastes great, which is a nice bonus since not many things you do in the chemistry lab are edible.
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Three colorless solutions are mixed together. The color of the mixture oscillates between clear, amber, and deep blue. After about 3-5 minutes, the liquid stays a blue-black color.
The Barking Dog chemistry demonstration is based on the reaction between nitrous oxide or nitrogen monoxide and carbon disulfide. Igniting the mixture in a long tube produces a bright blue flash, accompanied by a characteristic barking or woofing sound. The reaction can be used to demonstrate chemiluminescence, combustion, and exothermic reactions.
This color change demonstration is used to introduce pH indicators and acid-base reactions. Phenolphthalein is added to water, which is poured into a second glass containing a base. If the pH of the resulting solution is right, you can make the liquid switch between red and clear indefinitely.
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The red-clear color change of the water into wine or blood demo is classic, but you can use pH indicators to produce other color changes. The blue bottle demonstration alternates between blue and clear. These instructions also include information on performing a red-green demonstration.
Walkerma, Wikipedia Commons
This is a nice phase change demonstration. React a jar of liquid and an apparently empty jar to make smoke. The white smoke chemistry demonstration is easy to perform and visually appealing.
Iodine crystals are reacted with concentrated ammonia to precipitate nitrogen triiodide. The nitrogen triiodide is so unstable that the slightest contact causes it to decompose into nitrogen and iodine gas, producing a very loud 'snap' and a cloud of purple iodine vapor.