Chemistry Component

Balanced Ethanol Combustion:

C₂H₆O + 3O₂ > 3H₂O + 2CO₂

The concept behind these cannons firing is Gay-Lussac’s Gas Law, which states that pressure and temperature are directly related, or when temperature rises, so does the pressure.

The force that will (hopefully) shoot the cannonball is the increased pressure in the can due to the heat generated from an ethanol combustion. A few grams of ethanol in liquid form will be placed in the barrel. Ethanol has a low evaporation pressure so it will quickly turn to a gas. The gas with then be lit on fire and the heat from the combustion should increase the pressure so the cannonball fires.

The way we used this in our design is we also considered the effect volume has on pressure. Volume and pressure are inversely related, which means when one goes up, the other goes down. Since the same amount of ethanol will be used in each cannon, we made our barrel shorter than most by a little bit less than two inches. This change will hopefully increase the pressure in the barrel and make the ball shoot farther.