Hydrocarbons ability to combust, or burn, depends on the amount of oxygen available.
They can undergo complete combustion or incomplete combustion.
Complete combustion occurs when there is a plentiful supply of oxygen. The carbon and hydrogen atoms react with oxygen in an exothermic reaction.
hydrocarbon + oxygen → carbon dioxide + water
Here are the equations for the complete combustion of propane, which is used in bottled gas.
propane + oxygen → carbon dioxide + water
C3H8 + 5O2 → 3CO2 + 4H2O
Incomplete combustion occurs when there is a limited supply of oxygen.
Problems with incomplete combustion
Carbon monoxide is a poisonous gas. It binds with haemoglobin in red blood cells and prevents them from carrying oxygen. It is colourless and odourless, so it is difficult to tell if you are breathing it in – electronic detectors are often fitted near home boilers and gas fires.
Particulate (minute, separate particles) carbon can cause health problems. It irritates the lungs’ lining, making asthma worse and causing cancer. It also causes global dimming, which may reduce rainfall and limits light.