Convert Mass Flow Rate to Molar Flow Rate

[vishnu123]

TL;DR Summary

can someone tell me the relation between the molar flow rate and density with respect to mass flow rate?

how can i convert mass flow rate into molar flow rate using density of the gas.

 

[Chestermiller]

You can't do it using density. Just divide the mass flow rate by the molecular weight to get the molar flow rate.

 

[Dullard]

Mass flow may be described with a number of different units. I infer from your question that you may be starting with 'SLPM' or 'SCCM' - these are common mass flow meter units.

Chestermiller is correct, but getting from SLPM to the mass/time units does require the gas density. Specifically, it requires the 'standard' gas density assumed in the 'SLPM' units. In practice, everyone (who manufactures MFMs) uses their own version of 'standard' - mostly 0C vs 25C vs 70F reference temperature - it's an almost 10% error waiting to happen.

 

[vishnu123]

Thank you Chestermiller and Dullard for clarifying the doubt.

 

[FluidDroog]

Mass flow may be described with a number of different units. I infer from your question that you may be starting with 'SLPM' or 'SCCM' - these are common mass flow meter units.

Chestermiller is correct, but getting from SLPM to the mass/time units does require the gas density. Specifically, it requires the 'standard' gas density assumed in the 'SLPM' units. In practice, everyone (who manufactures MFMs) uses their own version of 'standard' - mostly 0C vs 25C vs 70F reference temperature - it's an almost 10% error waiting to happen.

You should use the standard ideal molar volume to convert the flow rate from molar units to standard cubic centimeters per minute (sccm). The standard conditions are defined as P= 101325 Pa, T=273.15 K and Z=1.

https://physics.nist.gov/cgi-bin/cuu/Value?mvolstd|search_for=molar+volume

From NIST, 1 sccm is approximately 0.74358 µmol/s.
https://tsapps.nist.gov/publication...4154&msclkid=d34cae6cabff11ec8093320a4d23498a