Explosion in a Bottle

In this experiment, you can create a small explosion contained in a bottle (most of the time. I never had the bottle explode itself...yet). All you have to do is save a soda bottle (plastic) and obtain some calcium carbide. Calcium carbide can be found at some hardware stores, and it is what is used in "Big Bang Cannons". It can also be found inside of CRTs, at the end of the electron gun. In CRTs it is used to absorb the remaining gases left after it is evacuated, but there is not much there so it may take a few CRTs to get enough calcium carbide for a small soda bottle. When calcium carbide mixes with water, it produces acetylene, a gas that is used in welding and cutting torches. This gas is what will be used as the explosive.

First you need to make a detonator out of the cap of the bottle. All you need to do is punch two holes in the top, put some wires through, and connect the wires to a heating element, or even a piece of steel wool. Or you could separate the wires and form a spark gap (this is what I use) which will require a high voltage power supply to create a spark (you can use the piezo ignitor from a grill, or one of the ignition coil high voltage generators). Then put silicone sealant around the wires where they go through the cap to form an air tight seal (you need this to hold the gas in).

After that, wrap the calcium carbide in toilet paper, twist the ends, and tape it closed. Next, pour some water in the bottle (not a lot, just enough to get the calcium carbide wet) and figure out a way to wedge the toilet paper with the calcium carbide in it between the two wires on the cap (when using the low voltage method with a heating element or a strand of steel wool, you will need to supply a little extra wire to wedge the toilet paper between. When using the high voltage method, you can just shove it between the spark gap for the time being). Then screw the lid on tight, and tap the bottle until the toilet paper falls in the water. Give it a minute to soak up the water and react to it. When you think its ready, turn on the power for the heating element, spark gap, etc... and if you got it right, you will get an explosion in a bottle (or even better, have the bottle explode). Just give yourself some wire from the bottle to where you will set it off, just in case the bottle does explode.

If when you set it off, it makes a very small explosion or nothing at all, and if the cap heated up/produced a spark, you may need to use more calcium carbide (also, make sure the calcium carbide you got is still active by pouring water on some of the grains. If it bubbles and makes a little gray smoke, it is active). Or if the bottle fills up with smoke and soot, you used too much calcium carbide. I am not exactly sure of the air to water to calcium carbide ratio for maximum combustion, but if anyone else does, please mail me.

The picture above is of a bottle after the explosion took place inside of it. This is my best one so far.

This is how I set up the bottle with everything in it (but there is no water it it, and the bottle wouldn't be deformed yet). You can see the toilet paper between the spark gap at the top, inside the bottle.

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