hi
i want to calculate the gas concentration, in ppm, in the closed chamber of volume 1025 cm3. i have a cylinder of mixture of NH3 and air with the 10 and 90% ratio respectively. we are flowing this gas mixture to the chamber at flow rate of 100 sccm. now how can i calculate the NH3 concentration in ppm inside the closed chamber ??
Hi Kaleem,
the concentration in ppm does not depend on flow rate or volume as long as the chamber has been evacuated before you introduce the mixture of NH3/air. The ppm measure simply says how many µg/g (weight) or molecules per million molecules (molar ratio) of NH3 there are in the mix.
Assuming that your 1:10 mix is calculated in weight, the concentration is 100,000 µg/g or ~170000 molecules/1,000,000 molecules of mix. The latter, higher molecular ratio arises from the fact that the molar mass of NH3 is lower than the average for air, i.e. per unit weight there are more molecules of NH3 than of the gas mix that makes up air.
If your gas mix of 1:10 is in molecules/molecules (partial pressures), the concentration of NH3 is ~59,000 µg/g or 100,000 molecules/1,000,000 molecules of mix.
Hope I got your question right...
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