# DENSITY OF GASES

Density, molecular mass and chemical formula of various gases including air, nitrogen (N2), helium (He), carbon dioxide (CO2) and Methane (CH4) at 25 °C and under 100 kPa pressure are given in the following gas density table.

Gas density is the ratio of its mass to volume,  and gases occupy their entire container, so its density is the mass of the gas divided by the containers volume.

 Density of Gases at 25 °C, 100 kPa ** Gas Chemical Formula Molecular Mass Density (ρ) kg / m3 Steam H2O 18.015 0.0231 Acetylene C2H2 26.038 1.05 Air -- 28.97 1.169 Ammonia NH3 17.031 0.694 Argon Ar 39.948 1.613 Butane C4H10 58.124 2.407 Carbon monoxide CO 28.01 1.13 Carbon dioxide CO2 44.01 1.775 Ethane C2H6 30.07 1.222 Ethanol C2H5OH 46.069 1.883 Ethylene C2H4 28.054 1.138 Helium He 4.003 0.1615 Hydrogen H2 2.016 0.0813 Methane CH4 16.043 0.648 Methanol CH3OH 32.042 1.31 Neon Ne 20.183 0.814 Nitric oxide NO 30.006 1.21 Nitrogen N2 28.013 1.13 Nitrous oxide N2O 44.013 1.775 n-octane C8H18 114.23 0.092 Oxygen O2 31.999 1.292 Propane C3H8 44.094 1.808 R-12 CCL2F2 120.914 4.98 R-22 CHCLF2 86.469 3.54 R-134a CF3CH2F 102.03 4.20 Sulfur dioxide SO2 64.059 2.618 Sulfur trioxide SO3 80.053 3.272

Note: ** Or saturation pressure if it is less than 100 kPa.

### Density of Gas Formula:

The density of gas is calculated with an alternative form of the ideal gas law. This formula is an expression of the ideal gas law in terms of density.

ρ = mP/nRT = MP/RT

where P is the gas pressure, n is mol of gas particles, R is the ideal gas constant, T is the temperature of gas, ρ is the density of gas, m is the mass and M is the molar mass of gas.

### Reference:

• Sonntag.R.E. , Borgnakke.C. , Van Wylen G.J. , (1998) . Fundamentals of Thermodynamics . 5th edition.  John Wiley & Sons Inc., pp 650