Gas Concentration: ppm by Volume vs mg/L

[gunnar]

a gas is x ppm by volume
Liquids are mg/L
but what about the gas?

 

[Astronuc]

ppm is a mass ratio -

ppm = parts per million = mg / kg = \mug/g

To get mole fraction, one has to divide by the appropriate molecular mass.

 

[thepatientmental]

Gas concentration is typically measured in parts per million (ppm) by volume, whereas liquids are measured in milligrams per liter (mg/L). This means that for a gas, the concentration is measured in terms of its volume in relation to the total volume of the mixture, while for a liquid, it is measured in terms of the mass of the substance in a given volume of the liquid.

For example, if a gas is 50 ppm by volume, it means that for every 1 million units of the mixture, 50 units are the specific gas. On the other hand, if a liquid has a concentration of 50 mg/L, it means that for every liter of the liquid, there are 50 milligrams of the substance.

It is important to note that ppm by volume and mg/L are not interchangeable units of measurement. They represent different ways of quantifying the concentration of a substance in a mixture. Additionally, the concentration of a gas can vary greatly depending on temperature and pressure, whereas the concentration of a liquid is not affected by these factors.

In summary, while liquids are measured in mg/L, gases are typically measured in ppm by volume. Both units are important for accurately determining the concentration of a substance in a mixture.