Shown here are four representations chemists use for methane. In the colored models, carbon is light gray and hydrogen is white.
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Windows to the Universe original artwork by Randy Russell.
Methane - CH4
Methane is gas
that is found in small quantities in Earth's
atmosphere. Methane is the simplest hydrocarbon,
consisting of one carbon atom and four hydrogen atoms.
Methane is a powerful greenhouse
Methane is flammable, and is used as a fuel worldwide. It is a principal component
of natural gas. Burning methane in the presence of oxygen
releases carbon dioxide
and water vapor:
CH4 + 2 O2 → CO2 + 2 H2O
Although the concentration of methane in Earth's atmosphere is small (around
1.8 parts per million), it is an important greenhouse
gas because it is such a potent heat absorber. The concentration of methane
in our atmosphere has risen by about 150% since 1750, apparently largely due
to human activities. Methane accounts for about 20% of the heating effects by
all of the greenhouse gases combined. Both natural and human sources supply
methane to Earth's atmosphere.
Major natural sources of methane include emissions from wetlands and oceans,
and from the digestive processes of termites. Sources related
to human activities include rice production, landfills, raising cattle and
other ruminant animals (cow burps!), and energy generation.
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