Question

The maximum contaminant level of cyanide (CN−) in drinking water set by the Environmental Protection Agency (EPA) is 0.00020 g/L. Express this concentration in parts per million (ppm). Assume the density of water is 1.00 g/mL.

a) 0.20 ppm
b) 0.002 ppm
c) 0.00020 ppm
d) 0.000002 ppm

Answer 1

The concentration of cyanide in drinking water set by the EPA at 0.00020 g/L is equivalent to 0.20 ppm since 1 ppm is equal to 1 mg in 1 L of water and the density of water is 1.00 g/mL.

Step-by-step explanation:

The maximum contaminant level of cyanide (CN−) in drinking water is set by the Environmental Protection Agency (EPA) at 0.00020 g/L. To express this concentration in parts per million (ppm), we use the density of water, which is 1.00 g/mL. Since 1 ppm is equivalent to 1 mg of solute in 1 L of solution, and 1 L of water weighs 1000 g, we can calculate the concentration in ppm by converting grams to milligrams and dividing by the volume in liters.

0.00020 g/L is the same as 0.20 mg/L since there are 1000 mg in a gram. Therefore, the concentration of cyanide in drinking water is 0.20 ppm.