Sciencemadness Discussion Board

What is ppm?

chornedsnorkack - 21-2-2024 at 04:14

Since 1 bar is 100 000 Pa, is 1 Pa partial pressure by definition 10 ppm?

DraconicAcid - 21-2-2024 at 04:58

Only if the total pressure is 1 bar.

Texium - 21-2-2024 at 06:09

1 ppm = 0.0001%

chornedsnorkack - 21-2-2024 at 08:12

Does this depend on molar mass?
Is ppm, as quoted in danger limits, smell thresholds, et cetera, in ml per million ml (m3), thus mPa per kPa? Or is it mg/kg?
When mercury at 20 C has saturated vapour pressure of 0,17 Pa, does it mean saturated mercury fumes are 1,7 ppm? Or are they 12 ppm (because Hg is also about 7 times the molar mass of air)?

Texium - 21-2-2024 at 08:30

For air, I believe ppm is generally defined as volume of selected gas / total volume of air. For liquids, it’s expressed as mg solute / kg solvent (and for dilute aqueous solutions, often serves as a shorthand for mg/L)

barbs09 - 25-2-2024 at 02:27

We use ppm (parts per million) as a useful measure of concentration of gold in ore, which we also interchange with grams per tonne i.e., 1ppm = 1g/tonne i.e there are 1 million grams in a metric tonne.