In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon.
Hydrocarbons are one of the Earth's most important (fossil) energy resources.
The predominant use of hydrocarbons is as a combustible fuel source
Hydrocarbons are currently the main source of the world's electric energy and heat sources
(such as home heating) because of the energy produced when burnt.
Often this energy is used directly as heat such as in home heaters,
which use either oil or natural gas.
The hydrocarbon is burnt and the heat is used to heat water,
A similar principle is used to create electric energy in power plants, e.g., steam turbines
driving electric generators..
Common properties of hydrocarbons are the facts that they produce steam,
carbon dioxide and heat during combustion and that oxygen is required
for combustion to take place. The simplest hydrocarbon, methane, burns as follows:
CH4 + 2 O2 ==> 2 H2O + CO2 + Energy
Another example of this property is propane:
C3H8 + 5 O2 ==> H2O + 3 CO2 + Energy
CnH2n+2 + (3n+1)/2 O2 ==> (n+1) H2O + n CO2 + Energy
Hydrocarbons evaporating rather than burned are a precursor to ground-level ozone, a serious air pollutant
in cities across the world. A key component of smog, ground-level ozone is
formed by reactions involving hydrocarbons and nitrogen oxides in the presence of sunlight.
Hydrocarbon emissions result from incomplete fuel combustion and from fuel evaporation.
Today's cars are equipped with emission controls (catalytical converters)
designed to reduce both exhaust and evaporative hydrocarbon emissions.