Methanol Cannon

Purpose:

A corked, 1 liter plastic bottle is clamped into position on a ring stand or buried in the ground with the cork up. An electric spark is applied with a Tesla coil or igniter from a gas grill causing a loud explosion to occur and propelling the cork from the mouth of the bottle. Wear goggles and use only a small amount of alcohol.

Materials:

• methanol (methyl alcohol) or ethanol (ethyl alcohol)

  Cork and 1 liter plastic bottle (shampoo or juice work best). You can reinforce the bottle with tape.

  igniter for a gas grill or Tesla coil

  two long nails (#8 up to #16)

  ring stand with a ring and testube holder or hole in the ground

Procedure:

1. Prepare the cannon by inserting the two nails into the sides of the heavy plastic bottle the points of which are 1/4 inch apart.

   Add 1 ml of methanol and no more, to the bottle and put the cork in, but not too tight.

   Shake the bottle to vaporize the alcohol.

   Securely fasten the bottle on the ring stand with a ring on the base and testube holder on the neck so the bottle cannot take off. If you are using the igniter from a gas grill then connect the wires to the nails (one wire per nail) now OR bury the bottle half way into the ground. Direct the cork away from people or breakable things.

   Allow a spark from a Tesla coil to contact one of the nails OR push the igniter.

   A loud explosion occurs and the cork will shoot out rapidly.

Another alternative is to use an empty Pringles can with the top on and poke a small hole about one inch from the bottom. Use an eyedropper to squirt some acetone or alcohol through the hole forcefully. Allow several minutes for the alcohol vapor to disperse. Get behind a lexon shield and bring a burning match to the hole. The explosion will send the top to the ceiling. If you do not wait long enough then the vapor will not mix properly with the air and no explosion will occur. Proper ratios are important.

Discussion:

The alcohol reacts quickly with the oxygen in the air when ignited by a spark. An exothermic reaction occurs that produces carbon dioxide and water. If this is done in a dark environment a blue flame will be seen.

2 CH₃OH_(l) + 3 O₂ --> 2 CO_{2 (g)} + 4 H₂O_(l)

An interesting alternative is to use 3 gram of calcium carbide in 2 cm of water to produce acetylene gas. A hole is needed in the side of the bottle where the burning match can be held. After a few seconds try igniting the mixture. If the gas just burns at the hole and no explosion occurs then too much gas was produced. Reduce the amount of carbide. The reactions are:

CaC_{2 (s)} + 2 H₂O_(l) ---> C₂H_{2 (g)} + Ca(OH)_{2 (aq)}

Combustion of acetylene is:

2 C₂H_{2 (g)} + 5 O_{2 (g)}---> 4 CO_{2 (g)} + 2 H₂O_(g)

Another similar experiment follows:

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