A wax fire is created when melted or boiling

wax Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to give low ...

is doused with water. The ensuing reaction creates a large fireball or dramatically enlarges the flame of the already existing

fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction Product (chemistry), products. At a certain point in the combustion reaction, called the ignition ...

. Only a small amount of wax and water is needed to create a wax fire.

Chemistry behind the reaction

Following the basic rules of the

fire triangle The fire triangle or combustion triangle is a simple model for understanding the necessary ingredients for most fires. The triangle illustrates the three elements a fire needs to ignite: heat, fuel, and an oxidizing agent (usually oxygen). A fir ...

, for a reaction to take place, three ingredients are required:

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

, fuel, and heat. In the case of wax melted down, only the top surface has access to oxygen, so the fire progresses slowly. When water is added to the wax, two things happen. Firstly, the water — being denser than wax — sinks to the bottom of the container. Secondly, as burning wax quickly reaches a temperature of well over 200 degrees C, the water instantly vapourises. When water changes from a liquid to a gas, there is more than a thousand-fold increase in volume. The water expands violently, and throws the hot wax layer above it into the air as small droplets. The wax now has a much bigger surface area exposed to oxygen so combustion takes place very quickly. For similar reasons, water should never be used to extinguish burning grease or fat, which both behave similarly to wax. Water is ineffective at putting out other flammable liquid fires, but in most liquids (e.g. petrol), the water remains as a liquid, and spreads the fire by allowing the liquid to float and burn on top of it. Baking soda more effectively extinguishes a wax fire.

External links

{{Commonscat *http://www.physicsforums.com/archive/index.php/t-83794.html *http://www.angliacampus.com/education/fire/secondar/fire.htm Articles containing video clips Types of fire *

Chemistry behind the reaction

See also

External links