Methane is a colorless, odorless, inflammable, and tasteless gas that is the primary component of natural gas.
Because CH4 is present naturally in the atmosphere, the general public may be exposed to very low levels when
breathing in air. Methane is lighter than air and has a specific gravity of 0.554. Methane gas density is 0.717
kg·m
−3
, melting point is −187˚C (86 K), boiling point −161˚C (112 K). This gas is only poorly soluble in water,
but is soluble in organic solvents. Naturally occurring methane is mainly produced by the process of methanogenesis [35]. This multistep process is used by microorganisms as an energy source. The reaction is:
CO2 + 8H
+
+ 8e
−→ CH4 + 2H2O