intro chemistry

Question

The maximum contaminant level of copper (Cu) in drinking water as set by the the Environmental Protection Agency (EPA) is 0.0013 g⋅L−1. Express this concentration in parts per million (ppm). Assume the density of water is 1.00 g/mL.

Answer 1

Parts per million (ppm) is another way of saying milligrams per liter (mg/L). They are the same and are equal.

We are given the number of grams which we will convert to mg.

We are given the number of liters which we will leave as is.

Number of mg = 0.0013 g x 1000 mg/g = 1.3 mg

Number of literes = 1 liter

mg/L = ppm = 1.3 mg/1 L = 1.3 ppm

(note: the density of water isn't necessarily used unless you want to report the level of copper as mg per 1000 mg of water instead of mg per 1000 ml (1 L) of water. The answer will be the same, ie 1.3 ppm)