A colourless and odourless gas, methane, or CH4, is the principle component of natural gas, and is known as a greenhouse gas, according to the Environmental Protection Agency, or EPA. It is a product of anaerobic bacterial environments that release the gas into the atmosphere. This usually occurs underwater in the absence of oxygen, giving methane a different name: marsh gas.
Methane is one part carbon and four parts hydrogen. Its melting point is minus 182.5 degrees Celsius or minus 296.5 degrees Fahrenheit. Methane boils at minus 162 degrees Celsius or 1424 degrees Celsius. Its specific gravity is 0.554, meaning it is lighter than air.
One of methane's properties is its ability to absorb terrestrial infrared radiation in the atmosphere before its exits into space. Anaerobic activities provide the source for the methane in the air. This absorption contributes to the warming of the planet, hence the name greenhouse gas. Methane is approximately 21 more times more powerful at warming the atmosphere than carbon dioxide, according to the EPA. Based upon historical records that rely upon air bubbles trapped in ice sheets, methane levels in the atmosphere are higher than at any time in the last 400,000 years, as of 2011. Methane breaks down after 12 years in the atmosphere, so the levels can drop if less methane is placed into the atmosphere in the future.
Methane ignites easily and is considered to be highly flammable. It burns easily in air and produces a very hot pale flame. Place it in a closed container and it will rupture and explode if exposed to enough heat. Leaks of methane in natural gas present danger for explosions. A mixture of methane and air when methane is between 5 and 14 per cent presents another situation for explosions. That mixture has been the source of several coal mine explosions, according to Encyclopedia Britannica.
At high temperatures, methane and steam yield carbon monoxide and hydrogen. The hydrogen takes part in the making of ammonia for fertilisers and explosives. Other chemicals derived from methane include methanol, chloroform, carbon tetrachloride and nitromethane, as described in the Encyclopedia Britannica. Another product from methane combustion is carbon black, which is used to reinforce rubber in automobile tires.