Question

Enter your answer in the provided box. Mercury (Hg) is present in trace amounts in coal, ranging from 50 to 200 ppb. A typical power plant burns 1.4 million tons of coal per year. Calculate tons of mercury in the coal based on the lower (50 ppb) and higher (200 ppb) concentrations.

Answer 1

Concentration of mercury in ppb (parts per billion) is given as

={Mass of mercury (tons)/Mass of coal (tons)}x10⁹

i.e. Mass of mercury

={(Concentration of mercury in ppb)x(Mass of coal (tons)}/10⁹

Given that mass of coal=1.4 million tons=1.4x10⁶ tons (1 million=10⁶)

So when concentration=50 ppb

Mass of mercury=(50 ppb)x(1.4 x 10⁶)/10⁹=0.07 tons

When concentration=200 ppb

Mass of mercury=(200 ppb)x(1.4x10⁶)/10⁹=0.28 tons