density of gas mixtures

[JamieMassie]

Hi

I need to calculate the density of a gas mixture
(60% oxygen/40% nitrogen) 20 deg C, 1 ata.

Is it as simple as using the densities of the individual gases and the proportions or are there other effects to take into account.

thanks

Jamie

 

[yates]

Provided there is no chemical interaction between the two gases to form a third substance, density of resulting mixture is in proportion to the concentration of each gas and its individual density.

 

[aviat]

You may have to account for RH (water vapor) because it will make mixture lighter. If it is a dry gas then disregard.

 

[TheTick]

Remember that nitrogen and oxygen combine into N2 and O2, so their respective molecular weights are double.

 

[TD2K]

Density = P * MW / ( Z * R * T) for a gas mixture.

Z is the compressibility factor for the mixture. You can take as 1.0 for your mixture and P and T.

MW is the molecular weight of the mixture. I'll assume the 60/40 split is on a vol or mol basis so the density of the mixture is 0.6 * 32 + .4 * 28 (these are approximate MW for O2 and N2, you can use more precise ones if you need.

Density is in lb/ft3
R is the gas constant, 10.73 psia*ft3/lbmole deg R
T is the temperature in deg R
P is the pressure in psia.