help----urgent:(

Hey,

I want to convert micrograms per cubic meter into parts per million, but getting confused with differnt formulas......if anyone can help and asap......thanks

[JohnS]

Originally Posted by Unregistered

Hey,

I want to convert micrograms per cubic meter into parts per million, but getting confused with differnt formulas......if anyone can help and asap......thanks

We need to know context. The usual context is a pollutant gas or dust in air.

If a pollutant gas in air, the micrograms in the numerator need to be converted to micromoles, which requires the molecular weight of the pollutant. The cubic meter of air in the denominator has to be converted to moles, which requires temperature and presure. (EPA and OSHA use 1 atm, 25 °C, where the answer is where the answer is 24.466 L/mol or 40.873 mol/m³), Then you have µmol/mol or ppm. (Gases are expressed as ppm by mole fraction)

Dusts are not converted to ppm, although theoretically it could be expressed as ppm by weight by converting the m³ of air to its weight in kg.