Question

How do we measure the concentration of a solution in `"parts per million"`?

Answer 1

You need the concentration in `g*L^-1`, and convert this to `"ppm"`. How?

Explanation:

`"ppm"` as you know is parts per million; literally `"milligrams per litre"`, i.e. `10^(-3) g*L^-1` (ppm because there are a million mg in `1*L` of water). It is typically used for trace quantities, and the density of the solvent (usually water) is almost identical to that of the pure solvent.