CAS Registry Number: 74-82-8
Additional Names: Marsh gas; methyl hydride
Molecular Formula: CH4
Molecular Weight: 16.04
Percent Composition: C 74.88%, H 25.14%
Literature References: Widely distributed in nature. American natural gas is about 85% methane. The earth's atm contains 0.00022% by vol. Major constituent of the atm of the outer planets (Jupiter, Saturn, Uranus, Neptune), exact figures in Landolt-Börnstein vol. III (Springer, 6th ed., 1952) p 59; G. P. Kuiper, The Atmospheres of the Earth and the Planets (University of Chicago Press, 1949). Pure carbon combines directly with pure hydrogen at temperatures above 1100° forming methane. Above 1500° amount of methane formed increases with temperature: Pring, J. Chem. Soc. 97, 498 (1910). Can be prepd from sodium acetate and sodium hydroxide, or from aluminum carbide and water: Matthews, J. Am. Chem. Soc. 21, 647 (1899); Carroll, J. Phys. Chem. 22, 148 (1918). Prepd commercially from natural gas or by fermentation of cellulose and sewage sludge: Cost, US 2583090 (1952 to Elliott Co.); Le Paige, de Dommartin, FR 994032 (1951), C.A. 51, 10836i (1957); Oswald, Golueke, Mech. Eng. 86, 40 (1964).
Properties: Colorless, odorless, non-poisonous, flammable gas. Burns with a pale, faintly luminous flame. d40 0.554 (air = 1) or 0.7168 g/liter. mp -182.6°. bp -161.4°. Crit temp -82.25°; crit pressure 45.8 atm. Heat of combustion 978 Btu/cu ft at 25° (a kilogram of CH4 yields 13,300 kcal). Forms exposive mixtures with air, the loudest explosions occur when one vol of methane is mixed with 10 vols of air (or 2 vols of oxygen). Air contg less than 5.53% methane no longer explodes. Air contg more than 14% methane burns without noise. Autoignition temp 650°. Soly in water at 17°: 3.5 ml/100 ml H2O. Sol in alc, ether, other organic solvents.
Melting point: mp -182.6°
Boiling point: bp -161.4°
Density: d40 0.554 (air = 1) or 0.7168 g/liter
CAUTION: Simple asphyxiant.
Use: Constituent of illuminating and cooking gas, in the manuf of hydrogen, hydrogen cyanide, ammonia, acetylene, formaldehyde, in organic syntheses.