how to convert 3.1 ppm to mg/l?

Answer 1

You don't have enough information. ppm is "parts per million," and mg/L is "milligrams per liter." ppm refers to numbers of particles (1 particle of the substance of interest for every 999,999 other particles), while mg/L depends on mass and volume. Both are ways of quantifying concentration. Without knowing the mass of the solvent and solute, we cannot convert between the two measurements.

The answer below contains an unsupported generalization. 1 ppm = 1 mg/L only in the specific case of small concentrations in water solutions. 3.1 ppm is a small concentration, but we have no information here that this is a water solution.

Answer 2

David is wrong!!! This is a very simple solution and no Wiki reference is needed :)

Always remember 1 ppm = 1 ug/ml so for that we get:

3.1ppm = 3.1 ug/ml *1000ml/L*1mg/1000ug= 3.1 mg/L so now you know:

1 ppm = 1 ug/ml = 1mg/L

hope that helps!