A sample of soil if found to contain 125 mg per kilogram of

A sample of soil if found to contain 12.5 mg per kilogram of soil of lead.  What is the concentration of lead in ppm and ppb for this sample?

Solution

Mass of lead = 12.5 mg

Mass of soil = kg = 10³ g = 10⁶ mg

Concentration of lead (ppm) = (mass of lead/mass of soil)x10⁶

= ( 12.5 mg/10⁶ mg)x10⁶

= 12.5 ppm

Concentration of lead (ppb) = (mass of lead/mass of soil)x10⁹

= (12.5 mg/10⁶ mg)x10⁹

= 12500 ppb