Molecular Weight - Gases and Vapors

Molecular mass of common gases and vapors

The molecular weight of a substance, also called molecular mass, is the mass of one molecule of that substance, relative to the unified atomic mass unit u equal to 1/12 the mass of one atom of carbon-12.

Gas or VaporMolecular Weight
(kg/kmole)
Acetylene, C2H2 26.04
Air 28.966
Ammonia (R-717) 17.02
Argon, Ar 39.948
Benzene 78.11
N-Butane, C4H10 58.12
Iso-Butane (2-Metyl propane) 58.12
Butadiene 54.09
1-Butene 56.108
cis -2-Butene 56.108
trans-2-Butene 56.108
Isobutene 56.108
Carbon Dioxide, CO2 44.01
Carbon Disulphide 76.13
Carbon Monoxide, CO 28.011
Chlorine 70.906
Cyclohexane 84.16
Deuterium 2.014
Ethane, C2H6 30.070
Ethyl Alcohol 46.07
Ethyl Chloride 64.515
Ethylene, C2H4 28.054
Fluorine 37.996
Helium, He 4.002602
N-Heptane 100.20
Hexane 86.17
Hydrochloric Acid 36.47
Hydrogen, H2 2.016
Hydrogen Chloride 36.461
Hydrogen Sulfide 34.076
Hydroxyl, OH 17.01
Krypton 83.80
Methane, CH4 16.044
Methyl Alcohol 32.04
Methyl Butane 72.15
Methyl Chloride 50.488
Natural Gas 19.00
Neon, Ne 20.179
Nitric Oxide, NO2 30.006
Nitrogen, N2 28.0134
Nitrous Oxide 44.012
N-Octane 114.22
Oxygen, O2 31.9988
Ozone 47.998
N-Pentane 72.15
Iso-Pentane 72.15
Propane, C3H8 44.097
Propylene 42.08
R-11 137.37
R-12 120.92
R-22 86.48
R-114 170.93
R-123 152.93
R-134a 102.03
R-611 60.05
Sulfur 32.02
Sulfur Dioxide (Sulphur Dioxide) 64.06
Sulfuric Oxide 48.1
Toluene 92.13
Xenon 131.30
Water Vapor - Steam, H2O 18.02

Related Topics

  • Material Properties - Material properties - density, heat capacity, viscosity and more - for gases, fluids and solids

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