Take a shot at the fire triangle

Shooting, although now a sport, was born out of an activity that was not created for recreational purposes. The activity itself was developed for two primary reasons. The first was to provide a mechanism to aid hunting and thus the provision of food and the second was as an offensive and defensive weapon to increase a society’s chance of survival.  

The link between shooting and chemistry is really in the chemical reaction that takes place when gunpowder ignites producing the energy needed to propel a bullet out of a gun. However before we explore gunpowder in more detail it is worth reminding ourselves of the fire triangle and combustion reactions. 

You may remember that the fire triangle is an inter-related set of three requirements for a fire to take place.  First there must be a source of fuel to burn – this will most commonly contain carbon. Second there must be oxygen present to allow the fuel to burn and for the carbon in the fuel to react with the oxygen, normally forming carbon dioxide, although other compounds including carbon monoxide are often also formed.

Finally there must be a heat source or ignition source which starts the reaction off. This is commonly a flame or a spark but it can be caused by electrical energy, amongst other things.   The energy which is given off, once the fuel has started to burn, then supplies the heat source or ignition source needed for continued reaction. The fire will only go out once either the oxygen supply or fuel supply is removed. Fire is an example of a combustion reaction. 

Combustion reactions are reactions with oxygen which are normally accompanied by a release of energy. Typically heat energy and light energy are produced when a combustion reaction is taking place. When something is on fire we normally associate that with heat and light being produced and fire is the most widely recognised visual example of a combustion reaction taking place. A coal or log fire is a great example of this where one can feel the heat and see the flames of the fire. Many of the combustion reactions we come across in our daily lives are as a result of a fuel being burnt in oxygen.

Carbon is often present in the fuel and is normally what is being burnt in the combustion reactions we encounter. In our earlier examples of a log or coal fire both the logs and coal have an extremely high percentage content of carbon. It is the carbon which is present in gunpowder which is the main fuel source of the combustion reaction which takes place, ultimately resulting in a bullet being propelled out of the gun barrel.