Conversions between PPM and density (mg/m3), mole fraction (mol%), and volume fraction
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May I ask how PPM is converted to density (mg/m3), mole fraction (mol%), and volume fraction? The conversion formula between ppm and mg/m3 is: mg/m3 = (M/22.4)×××ppm. Is this formula correct (according to Baidu Baike)? Compare this with a formula derived solely from order-of-magnitude considerations: mg/m3 = Vm/Ma × ppm. Which one is correct and which one is incorrect?
In general industrial conversions, temperature and pressure are not taken into account; PPM = mg/m3 * 22.4 / M.
The milligrams per cubic meter here should represent the mass concentration
This post was last edited by qugd on 2020-7-30 09:31. For gases, the basic principle is that the volume ratio is equal to or approximately equal to the molar ratio; in addition, actual ratio conversions are carried out based on dimensional units, and density and molecular weight are generally involved in such calculations. Once you master this principle, calculation becomes quite easy. For solutions, it is necessary to consider whether the units of the solute and the solvent need to be standardized; ratios, percentages, and parts per million all require taking into account the conversion relationships between different units. Additionally, factors such as density and molecular weight (atomic weight for ions) also need to be considered.
I didn’t take that into account when I was calculating: L
That makes sense; the solution indeed deserves more consideration