Worksheet: Parts per Million and Parts per Billion

In this worksheet, we will practice calculating the concentrations of mixed or dissolved compounds in units of parts per million and parts per billion.


According to the US Environmental Protection Agency, when the concentration of lead in tap water reaches 15 ppb, certain remedial actions must be taken.

What is this concentration in parts per million?

At this concentration, what mass of lead (µg) would be contained in a typical glass of water (300 mL), assuming a density of 1.0 g/mL?


What is the mass of fish that one would have to consume to obtain a fatal dose of mercury, if the fish contains 30 parts per million of mercury by weight? Assume that all the mercury from the fish is stored as mercury(II) chloride in the body and that a fatal dose is 0.20 g of HgCl2.

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