Question

The EPA has set the legal limit (known as the maximum contaminant level or MCL) for the concentration of mercury as 0.0020 ppm. What is the concentration in parts per billion (ppb)?The EPA has set the MCL for the concentration of benzene as 5.0 ppb. What is the concentration in parts per million (ppm)?

Answer 1

Ans. 1 ppm = 1 mg of solute / L of solution OR 1 mg of solute / kg of solution

            1 ppb = 1 ug of solute / L of solution OR 1 ug of solute / kg of solution

So,

            1 ppm = 10³ x ppb

            1 ppb = 10^-3 x ppm

#1. 0.002 ppm = 10³ x 0.002 ppb = 2.0 ppb

#2. 5.0 ppb = 5.0 x 10^-3 ppm = 0.005 ppm