Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

Air - Diffusion Coefficients of Gases in Excess of Air

Diffusion coefficients (D12) for gases in large excess of air at temperatures ranging 0 - 400 °C.

Sponsored Links

Fick's first law states that a substance will flow from a region with high concentration to a region of low concentration. Fick's law can be expressed as

J = -D*dφ/dx                                  [1]


J = diffusion flux - the amount of substance that flows through an unit area per unit time [mass or mol /(m2 s)]
D = diffusion coefficient [m2/s]
dφ = change in concentration of substance [mass or mol/m3]
dx = change in length [m]

For simple one-dimensional transport, the diffusion coefficient describes the time–rate of change of concentration. The diffusion coefficient varies from substance to substance and with temperature and pressure.

Figure and table below shows the diffusion coefficients, D12, for binary gas mixtures where air is in large excess.

See also Air Composition and molecular weightDensity at varying pressure, Density and specific weight at varying temperature, Diffusion coefficients for gases in airDynamic (absolute) and kinematic viscosity, Prandtl Number, Specific heat at varying temperature and Specific heat at varying pressureThermal conductivityThermal diffusivity, Properties at gas-liquid equilibrium conditions and Air properties, for other properties of air, as well as Diffusion coefficients of gases in water and Carbon dioxide concentrations in rooms with people

Diff coeff gas air temperature C

Gases in large excess of air Diffusion coefficient, D12, [cm2/s]
at atmospheric pressure and given temperatures
0 °C 20 °C 100 °C 200 °C 300 °C 400 °C
Name Formula 32 °F 68 °F 212 °F 392 °F 572 °F 752 °F
Argon Ar 0.167 0.189 0.289 0.437 0.612 0.81
Methane CH4 0.21 0.321 0.485 0.678 0.899
Carbon monoxide CO 0.208 0.315 0.475 0.662 0.875
Carbon dioxide CO2 0.16 0.252 0.39 0.549 0.728
Hydrogen H2 0.668 0.756 1.153 1.747 2.444 3.238
Water vapour H2O 0.219 0.242 0.399 0.638 0.873 1.135
Helium He 0.617 0.697 1.057 1.594 2.221 2.933
Sulfur hexafluoride SF6 0.15 0.233 0.329 0.438
Sponsored Links

Related Topics

Related Documents

Sponsored Links

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro .Add the Engineering ToolBox extension to your SketchUp from the SketchUp Pro Sketchup Extension Warehouse!

About the Engineering ToolBox!


We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.


This page can be cited as

  • Engineering ToolBox, (2018). Air - Diffusion Coefficients of Gases in Excess of Air. [online] Available at: [Accessed Day Mo. Year].

Modify access date.

. .


3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Scientific Online Calculator

Scientific Calculator

3 30

Sponsored Links