1. The problem statement, all variables and given/known data Mercury poisoning is a debilitating disease that is often fatal. In the human body, mercury reacts with essential enzymes leading to irreversible inactivity of these enzymes. If the amount of mercury in a polluted lake is 0.4 μg Hg/mL, what is the total mass in kilograms of mercury in the lake? (The lake has a surface area of 100 mi2 and an average depth of 20 ft.) 2. Relevant equations mass = density * volume 3. The attempt at a solution I tried converting the density to Kg and the volume to cm3 = mL Mass = density * volume = ( (0.4 μg)(1 g/ 106 μg) (10-3 kg / 1 g) ) * ( (100 mi2)(52802 ft2 / 1 mi2)(30.482 cm2 / 1 ft2) (20 ft)(30.48 cm / 1 ft) ) My answer is 6 x 105 kg however the textbook says it's 7 x 105 kg.