If a source of drinking water is contaminated with 5.1 PPM by mass of lead, and you drink a 1 kg of it, how many grams of lead have you consumed?

Question

If a source of drinking water is contaminated with 5.1 PPM by mass of lead, and you drink a 1 kg of it, how many grams of lead have you consumed?

Answer 1

5.1 PPM means that there are 5.1 x 10^-6 kg of lead in 1 kg of water. Alternatively, you can think of it as 5.1 mg of lead per kg of water (since 1 mg = 10^-6 kg). Therefore, the answer to this problem is (5.1 mg/kg)(1kg) = 5.1 mg of lead.