What is Methane?
Methane is a chemical compound with the chemical formula CH4.
Methane is a colorless, odorless gas with a wide distribution in nature. It is the principal component of natural gas, a mixture containing about:
- 75% methane (CH4)
- 15% ethane (C2H6), and
- 5% other hydrocarbons - such as propane (C3H8) and butane (C4H10).
Anaerobic bacterial decomposition of plant and animal matter produces marsh gas which is also methane. In its natural state, methane is found both below ground, and under the sea floor. Methane is used in industrial chemical processes and may be transported as a refrigerated liquid (liquefied natural gas, or LNG). While leaks from a refrigerated liquid container are initially heavier than air due to the increased density of the cold gas, the gas at ambient temperature is lighter than air.
At room temperature, methane is a gas less dense than air. It melts at –183°C and boils at –164°C. It is not very soluble in water. Methane is combustible, and mixtures of about 5% to 15% in air are explosive. Methane is not toxic when inhaled, but it can produce suffocation by reducing the concentration of oxygen inhaled. A trace amount of smelly organic sulfur compounds (tertiary-butyl mercaptan, (CH3)3CSH and dimethyl sulfide, CH3–S–CH3) is typically added to give commercial natural gas a detectable odor. This is done to make gas leaks easily detectible. An undetected gas leak could result in an explosion or asphyxiation.
The principal use of methane is as a fuel. The combustion of methane is highly exothermic:
CH4(g) + 2O2(g) ------ CO2(g) + 2H2O(l)
