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How do I Calculate Bulk Concentration?

How do I Calculate Bulk Concentration?

How do I Calculate Bulk Concentration?

(OP)
Hello,
I'm trying to calculate the bulk concentration of Oxygen in Air and Hydrogen in pure Hydrogen in mol cm-3.

I have looked on websites but couldn't find any answer.
Can anyone please help.

RE: How do I Calculate Bulk Concentration?


I hope I understood your query.
Consider that 1 mol of an ideal gas at NTP occupies 22.4 L = 22,400 cm3.
NTP is taken at 0oC and 101.3 kPa.

For oxygen at 21% vol in air → 0.21÷22,400   mol/cm3

For hydrogen at 100% vol → 1.0÷22,400   mol/cm3
 

RE: How do I Calculate Bulk Concentration?

(OP)
Thanks a lot for the reply.
I'm sorry for my ignorance in the subject but what does NTP stand for?

RE: How do I Calculate Bulk Concentration?

NTP stands for "Normal Temperature and Pressure".  You will also see STP fairly often in this business.  It stands for "Standard Temperature and Pressure".  Not to overly confuse the issue, but the "definition" of what is normal and what is standard can also vary, depending on the particular industry and depending on whether SI or FPS units are used.
Doug

RE: How do I Calculate Bulk Concentration?

(OP)
Thanks Doug,
The application will be running at 80 C the previously given figures for the bulk concentration were given at a NTP of 0, does this mean that the figures would change?
If so then how would I work it out?

RE: How do I Calculate Bulk Concentration?

The volume of 1 mol of an ideal gas at 1 atm. abs. and 273 K, is computed as follows:

V = nRT/P = (1.0 mol)(8.314J/K.mol)(273 K)÷1.013 ×105 Pa
= 22.4×10-3 m3 = 22.4 L

If the "new" conditions are 1 atm abs (101.3 kPa) and 80oC, and applying the above ideal gas law, the "new" volume would be proportional to the "new" absolute temperature of (273+80=) 353 K.

The "new" volume would be: 22,400 × 353÷273 ~ 29,000 cm3/mol. This fact reduces the number of mols/cm3 accordingly.

Kindly note these molecular gases have been considered ideal. Changes in pressure and temperature removes them from ideality. To get their actual molar volumes at varying conditions you may use the following link:

http://webbook.nist.gov/chemistry/

After writing the gas name point to "fluid properties" and select m3/mol

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