For example, the gases fraction contains hydrocarbons with one to four carbon atoms. These have:
The hydrocarbons in different fractions differ in these properties. For example, the bitumen fraction contains hydrocarbons with more than 35 carbon atoms. These have:
Complete combustion of a hydrocarbon fuel happens when there is a good supply of air. Carbon and hydrogen atoms in the fuel react with oxygen in an exothermic reaction:
In a Bunsen burner, this occurs when the air hole is fully open.
hydrocarbon + oxygen → carbon dioxide + water
Here are the equations for the complete combustion of propane, used in bottled gas:
propane + oxygen → carbon dioxide + water
C3H8 + 5O2 → 3CO2 + 4H2O
Write a balanced equation for the complete combustion of methane, CH4, found in natural gas.
CH4 + 2O2 → CO2 + 2H2O
Incomplete combustion happens when the supply of air or oxygen is poor. Water is still produced, but carbon monoxide and carbon are produced. Less energy is released than during complete combustion.
In a Bunsen burner, incomplete combustion occurs when the air hole is closed.
You will learn more about incomplete combustion in Polluting the atmosphere.