Methane

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Figure 1. Space filling model of methane; the white spheres represent hydrogen atoms and the black spheres represent carbon atoms.[1]

Methane is an alkane with the chemical formula CH4. As a hydrocarbon, it can undergo hydrocarbon combustion which gives off heat. Methane is the main hydrocarbon component of natural gas, which is a type of fossil fuel.[2]

At typical temperatures and pressures it is a gas and makes up around 95% of the content of liquefied natural gas, and around 80-90% of natural gas.[3] Methane is also a greenhouse gas, like carbon dioxide (CO2). It has a shorter atmospheric lifetime than CO2, at 12 years,[4] but this is "balanced" by the fact that it is more effective at trapping heat than CO2, as methane has a GWP (Global warming potential) of 21.[5]

Methane combustion (see simulation at bottom of page) provides a significant fraction of the world's primary energy, and is used for home heating, cooking food, heating water, and electrical generation. It can even provide energy for transportation. However, this means that it is also a significant contributor to climate change since this methane produces a fair amount of the carbon dioxide that humans emit into the atmosphere.

Properties

Below is a table of some of the basic properties of methane.

Chemical formula CH4
Molar mass 16.04 grams/mole
Energy density[6] 55.5 MJ/kg
Melting point -183oC[7]
Boiling point -164oC[7]
GWP 21
Atmospheric lifetime 12 years

Combustion Animation

Methane releases its chemical energy by undergoing hydrocarbon combustion. Below is a hydrocarbon combustion animation showing the net reaction that occurs when methane combines with oxygen.

CH4 + 2O2 → CO2 + 2H2O Heat Energy (Enthalpy)

The hydrocarbon combustion reaction releases heat energy and is an example of an exothermic reaction. The reaction also has a negative enthalpy change (ΔH) value.

For Further Reading

References

  1. (2014, Dec. 12). Methane-3D-space-filling [Online]. Available: http://commons.wikimedia.org/wiki/File:Methane-3D-space-filling.svg#mediaviewer/File:Methane-3D-space-filling.svg
  2. “NATURAL GAS FAQs,” Pacific Northern Gas RSS. [Online]. Available: http://www.png.ca/natural-gas-faqs/. [Accessed: 24-May-2017]
  3. (2014, Jun. 10). Composition of Natural Gas and LNG [Online]. Available: http://www.beg.utexas.edu/energyecon/lng/LNG_introduction_07.php
  4. (2014, Jun. 10). Direct Global Warming Potentials [Online]. Available: http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2-10-2.html
  5. Direct Global Warming Potentials [Online]. Available: http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2-10-2.html [Accessed: 24-May-2017.
  6. (2014, Dec. 12). Chemical Potential Energy [Online]. Available: http://physics.info/energy-chemical/
  7. 7.0 7.1 (2015, Jan. 29). Boiling Points And Structures Of Hydrocarbons [Online]. Available: http://www.elmhurst.edu/~chm/vchembook/501hcboilingpts.html

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Authors and Editors

Semaa Amin, Allison Campbell, Jordan Hanania, James Jenden, Kailyn Stenhouse, Daniel Suchet, Jason Donev
Last updated: June 25, 2018
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