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Combustion of hydrocarbon fuels

can undergo complete or incomplete combustion, depending on the amount of oxygen available.

happens when there is a good supply of air. Carbon and hydrogen atoms in the hydrocarbon fuel react with oxygen in an reaction:

  • and water are produced
  • is given out

Carbon dioxide is an atmospheric . Incomplete combustion produces other pollutants.

Incomplete combustion

happens when the supply of air or oxygen is poor. Water is still produced, but and carbon are produced. Less energy is released than during complete combustion.

For example, here is one possible equation for the incomplete combustion of propane:

propane + oxygen 鈫 carbon + carbon monoxide + water

C3H8 + 3O2 鈫 C + 2CO + 4H2O

Soot

The carbon is released as fine black . We see this in smoky flames, and it is deposited as . Soot can cause breathing problems and it blackens buildings. It may block boilers and other appliances, or cause a fire.

Incomplete combustion produces smoke and invisible carbon monoxide
Image caption,
Incomplete combustion produces smoke and invisible carbon monoxide

Carbon monoxide

Carbon monoxide is a gas. It is absorbed in the lungs and binds with the in the . This reduces the capacity of the blood to carry oxygen. Carbon monoxide causes drowsiness, and affected people may fall unconscious or even die.