Gases - Densities

Densities and molecular weights of some common gases - acetylene, air, methane, nitrogen, oxygen and many others ..

Densities, molecular weight and chemical formulas of some common gases can be found in the table below:

GasFormulaMolecular
weight
Density - ρ -
(kg/m3) (lb/ft3)
Acetylene (ethyne) C2H2 26 1.0921)
1.1702)
0.06821)
0.07292)
Air 29 1.2051)
1.2932)
0.07521)
0.08062)
Ammonia NH3 17.031 0.7171)
0.7692)
0.04481)
0.04802)
Argon Ar 39.948 1.6611)
1.78372)
0.10371)
0.1113532)
Benzene C6H6 78.11 3.486 0.20643
Blast furnace gas 1.2502) 0.07802)
Butane C4H10 58.1 2.4891)
2.52)
0.15541)
0.1562)
Butylene (Butene) C4H8 56.11 2.504 0.1482)
Carbon dioxide CO2 44.01 1.8421)
1.9772)
0.11501)
0.12342)
Carbon disulphide 76.13
Carbon monoxide CO 28.01 1.1651)
1.2502)
0.07271)
0.07802)
Carbureted Water Gas 0.048
Chlorine Cl2 70.906 2.9941) 0.18691)
Coal gas 0.582)
Coke Oven Gas 0.0342)
Combustion products 1.112) 0.0692)
Cyclohexane 84.16
Digester Gas (Sewage or Biogas) 0.062
Ethane C2H6 30.07 1.2641) 0.07891)
Ethyl Alcohol 46.07
Ethyl Chloride 64.52
Ethylene C2H4 28.03 1.2602) 0.07862)
Helium He 4.02 0.16641)
0.17852)
0.010391)
0.0111432)
N-Heptane 100.20
Hexane 86.17
Hydrogen H2 2.016 0.08992) 0.00562)
Hydrochloric Acid 36.47 1.632)
Hydrogen Chloride HCl 36.5 1.5281) 0.09541)
Hydrogen Sulfide H2S 34.076 1.4341) 0.08951)
Krypton 3.742)
Methane CH4 16.043 0.6681)
0.7172)
0.04171)
0.04472)
Methyl Alcohol 32.04
Methyl Butane 72.15
Methyl Chloride 50.49
Natural gas 19.5 0.7 - 0.92) 0.044 - 0.0562)
Neon Ne 20.179 0.89992) 0.0561792)
Nitric oxide NO 30.0 1.2491) 0.07801)
Nitrogen N2 28.02 1.1651)
1.25062)
0.07271)
0.0780722)
Nitrogen Dioxide NO2 46.006
N-Octane 114.22
Nitrous Oxide N2O 44.013 0.114
Nitrous Trioxide NO3 62.005
Oxygen O2 32 1.3311)
1.42902)
0.08311)
0.0892102)
Ozone O3 48.0 2.142) 0.125
N-Pentane 72.15
Iso-Pentane 72.15
Propane C3H8 44.09 1.8821) 0.11751)
Propene (propylene) C3H6 42.1 1.7481) 0.10911)
R-11 137.37
R-12 120.92
R-22 86.48
R-114 170.93
R-123 152.93
R-134a 102.03
Sasol 0.032
Sulfur S 32.06 0.135
Sulfur Dioxide SO2 64.06 2.2791)
2.9262)
0.17031)
0.18282)
Sulfur Trioxide SO3 80.062
Sulfuric Oxide SO 48.063
Toluene C7H8 92.141 4.111 0.2435
Water Vapor, steam H2O 18.016 0.804 0.048
Water gas (bituminous) 0.054
Xenon 5.862)

1) NTP - Normal Temperature and Pressure - is defined as air at 20oC (293.15 K, 68oF) and 1 atm ( 101.325 kN/m2, 101.325 kPa, 14.7 psia, 0 psig, 30 in Hg, 760 torr)

2) STP - Standard Temperature and Pressure - is defined as air at 0oC (273.15 K, 32oF) and 1 atm (101.325 kN/m2, 101.325 kPa, 14.7 psia, 0 psig, 30 in Hg, 760 torr)

  • 1 lbm/ft3 = 16.018 kg/m3
  • 1 kg/m3 = 0.0624 lbm/ft3

Note that even if pounds per cubic foot is often used as a measure of density in the U.S., pounds are really a measure of force, not mass. Slugs are the correct measure of mass. You can divide pounds per cubic foot by 32.2 for a rough value in slugs.

Related Topics

  • Gas and Compressed Air - Gas properties, capacities of pipelines, sizing of relief valves - air, LNG, LPG and more
  • Material Properties - Material properties - density, heat capacity, viscosity and more - for gases, fluids and solids

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