Density of some common Gases
Densities and molecular weights of common gases like acetylene, air, methane, nitrogen, oxygen and others.
Densities, molecular weight and chemical formulas of some common gases can be found in the table below:
| Gas | Formula | Molecular weight | Density (kg/m3) | Density (lb/ft3) |
|---|---|---|---|---|
| Hydrogen | H2 | 2.016 | 0.08992 | 0.00562 |
| Helium | He | 4.02 | 0.16641 0.17852 |
0.010391 0.0111432 |
| Methane | CH4 | 16.043 | 0.6681 0.7172 |
0.04171 0.04472 |
| Ammonia | NH3 | 17.031 | 0.7171 0.7692 |
0.04481 0.04802 |
| Water Vapor, steam | H2O | 18.016 | 0.804 | 0.048 |
| Natural gas | 19.5 | 0.7 – 0.92 | 0.044 – 0.0562 | |
| Neon | Ne | 20.179 | 0.89992 | 0.0561792 |
| Acetylene (ethyne) | C2H2 | 26 | 1.0921 1.1702 |
0.06821 0.07292 |
| Carbon monoxide | CO | 28.01 | 1.1651 1.2502 |
0.07271 0.07802 |
| Nitrogen | N2 | 28.02 | 1.1651 1.25062 |
0.07271 0.0780722 |
| Ethylene | C2H4 | 28.03 | 1.2602 | 0.07862 |
| Air | 29 | 1.2051 1.2932 |
0.07521 0.08062 |
|
| Nitric oxide | NO | 30.0 | 1.2491 | 0.07801 |
| Ethane | C2H6 | 30.07 | 1.2641 | 0.07891 |
| Oxygen | O2 | 32 | 1.3311 1.42902 |
0.08311 0.0892102 |
| Methyl Alcohol | 32.04 | |||
| Sulfur | S | 32.06 | 0.135 | |
| Hydrogen Sulfide | H2S | 34.076 | 1.4341 | 0.08951 |
| Hydrochloric Acid | 36.47 | 1.632 | ||
| Hydrogen Chloride | HCl | 36.5 | 1.5281 | 0.09541 |
| Argon | Ar | 39.948 | 1.6611 1.78372 |
0.10371 0.1113532 |
| Propene (propylene) | C3H6 | 42.1 | 1.7481 | 0.10911 |
| Carbon dioxide | CO2 | 44.01 | 1.8421 1.9772 |
0.11501 0.12342 |
| Nitrous Oxide | N2O | 44.013 | 0.1141 | |
| Propane | C3H8 | 44.09 | 1.8821 | 0.11751 |
| Nitrogen Dioxide | NO2 | 46.006 | ||
| Ethyl Alcohol | 46.07 | |||
| Ozone | O3 | 48.0 | 2.142 | 0.125 |
| Sulfuric Oxide | SO | 48.063 | ||
| Methyl Chloride | 50.49 | |||
| Butylene (Butene) | C4H8 | 56.11 | 2.504 | 0.1482 |
| Butane | C4H10 | 58.1 | 2.4891 2.52 |
0.15541 0.1562 |
| Nitrous Trioxide | NO3 | 62.005 | ||
| Sulfur Dioxide | SO2 | 64.06 | 2.2791 2.9262 |
0.17031 0.18282 |
| Ethyl Chloride | 64.52 | |||
| Chlorine | Cl2 | 70.906 | 2.9941 | 0.18691 |
| Methyl Butane | 72.15 | |||
| N-Pentane | 72.15 | |||
| Iso-Pentane | 72.15 | |||
| Carbon disulphide | 76.13 | |||
| Benzene | C6H6 | 78.11 | 3.486 | 0.20643 |
| Sulfur Trioxide | SO3 | 80.062 | ||
| Cyclohexane | 84.16 | |||
| Hexane | 86.17 | |||
| R-22 | 86.48 | |||
| Toluene | C7H8 | 92.141 | 4.111 | 0.2435 |
| N-Heptane | 100.20 | |||
| R-134a | 102.03 | |||
| N-Octane | 114.22 | |||
| R-12 | 120.92 | |||
| R-11 | 137.37 | |||
| R-123 | 152.93 | |||
| R-114 | 170.93 | |||
| Blast furnace gas | 1.2502 | 0.07802 | ||
| Carbureted Water Gas | 0.048 | |||
| Coal gas | 0.582 | |||
| Coke Oven Gas | 0.0342 | |||
| Combustion products | 1.112 | 0.0692 | ||
| Digester Gas (Sewage or Biogas) | 0.062 | |||
| Krypton | 3.742 | |||
| Sasol | 0.032 | |||
| Water gas (bituminous) | 0.054 | |||
| Xenon | 5.862 |
1. NTP – Normal Temperature and Pressure – is defined as 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 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.