10. The Rubens Tube
This is a great way to demonstrate the phenomenon of sound waves. A Rubens Tube is simply a copper tube with a propane feed at one end and an acoustic speaker at the other. Holes are drilled along the top, and when lit with the speaker playing, this gives a graphic equalizer-like appearance to the sound waves. Cancelling or null waves can even be demonstrated with this device, and it also reveals how sound waves create air pressure.
9. Lowering Your Voice Using Sulfur Hexafluoride
Pitch-raising helium has an opposite in the gas sulfur hexafluoride. This gas is inert, denser than air, (that’s what lowers the pitch of your voice) and non-spark conducting, which is where it occasionally finds its use in industrial and lab applications. While safe to breathe like helium, sulfur hexafluoride is also hard to come by and has to be ordered from a scientific supply company.
8. Aluminum Cans in an Acid Versus a Base
This one demonstrates the reactive properties of aluminum (or do you say aluminium?) Place a pair of aluminum soda cans in sodium hydroxide (a strong base) and hydrochloric acid and watch the reaction — under a gas-venting hood, of course. The base reaction will generate sodium aluminate, while the acid reaction releases aluminum chloride and water. The result is not at all what you would expect.
7. Extracting Iron From Breakfast Cereal
Sure, we’ve all heard that cereal is fortified with iron, but have you ever actually seen it? This one only requires a magnet, a mortar and pestle (to pulverize the cereal) plastic bags, and a cereal known to be high in iron. After crushing up the cereal, you should be able to see tiny “flecks” of iron attached to the magnet. (Hint: a strong nickel-iron-boron magnet works best.)
6. Vanishing Dye Demonstration
A reaction between hydrogen peroxide and potassium permanganate (a staple in many high school science labs) is bizarre and fun to watch. Diluted in water, potassium permanganate has a characteristic purple color. When poured into the hydrogen peroxide solution, however, it reacts quicker than it is added in, vanishing as it is being poured. This reaction also releases oxygen in the process.
5. The Exploding Pumpkin
This is a cool one to do around Halloween, but also the most dangerous one on the list. Pre-carve out the face of the pumpkin, add water plus reactant and an ignition source inside, and close the top; the combustion of the resultant acetylene gas will blow out the face of the pumpkin. Drilling a small hole in the back of the pumpkin to stick a long tube barbeque lighter into it can help… again, one that’s to be done under safety supervision only.
4. Measuring the Speed of Light in a Microwave
Here’s a way to measure the cosmological speed limit, right in your own kitchen. Take a chocolate bar (or a row of chocolates) and place them in a microwave. Make sure that the rotation function is turned off, and the chocolate is placed lengthwise in the microwave. Run it just enough that the surface of the bar begins to melt slightly, and measure the distance between the two points of greatest softening. Now multiply that by 2 (to get the wavelength) and then multiply that by the frequency of the microwave, which should be listed on an identification plate located on the oven. And viola, you’ve rediscovered c, the speed of light!
3. The Infamous Vanishing Gallium Spoon
This one used to be a great 18th century pallor trick. Serve up boiling hot tea, and watch the look on the face of your guests as their gallium spoon vanishes in the liquid. This works because the metal gallium has an extremely low melting point, 85.59° Fahrenheit, to be precise. In fact, just holding a piece of pure gallium in your hand can cause it to begin melting! There are even several suppliers of “gallium spoon kits” around the web.
2. Mentos Reacting with Diet Coke
OK, maybe that’s too cliché by now … but the vigorous reaction caused by dropping a roll of Mentos in Diet Coke has been a web sensation and has quickly become a science classic. It’s almost as interesting to note the discussion that this has also sparked as to why this energetic reaction occurs. The carbon dioxide releasing reaction is a result of interaction between the gum arabic and gelatin in the Mentos and the aspartame and the potassium benzoate in the Diet Coke. Mentos is ideal because the surface contains tiny nucleation sites, increasing the surface area and speeding up the reaction.
1. Crush a Can Using Air Pressure
A classic science class experiment. Take an aluminum can, cut off one end, and heat it over a Bunsen burner (a barbecue grill works great, too). While still grasping the can with tongs, rapidly submerge the open end in water and let the air pressure difference inside the rapidly cooling can do the rest. While this experiment can be done in a lab, it can be scaled up too; note that the teacher in the video was brave enough to use a 55-gallon drum, to great effect. Just when the experiment seems doomed, fast forward to the 2:20 mark for the payoff.