A solution contains 15 ppm of benzene. The density of the solution is 1.00 g/mL. This means that
A) there are 15 mg of benzene in 1.0 L of this solution
B) 100 g of the solution contains 15 g of benzene
C) 100 g of the solution contains 15 mg of benzene
D) the molarity of the solution is 15
E) the solution is 15% by mass of benzene

Question

Quizplus · Accepted Answer

ppm (parts per million) is a unit of concentration, which represents the number of parts (in this case, benzene) per million parts of solution. Therefore, 15 ppm of benzene means that there are 15 mg of benzene in 1.0 L (or 1000 mL) of the solution. Since the density of the solution is 1.00 g/mL, 1 L (or 1000 mL) of the solution weighs 1000 g (or 1 kg). Therefore, there are 15 mg of benzene in 1.0 L (or 1000 mL or 1000 g) of the solution, which is the same as 15 mg/L or 15 mg/kg or 15 mg/g.

A Solution Contains 15 Ppm of Benzene