Question

Parts per million (ppm) is a common way to express small concentrations of a solute in water. A sample of tap water that is 25 ppm Cl−Cl− contains 25 grams of Cl−Cl− for every 1,000,000 grams of water. Which units are numerically equal to ppm for dilute aqueous solutions?

A. μg/L
B. cg/L
C. ng/L
D. mg/L
E. g/L

Answer 1

Answer:

Option D = mg /L

Explanation:

25 ppm of Cl = 25 g / 1000,000 g of water

we will convert g into Kg,

1000,000 / 1000 = 1000 kg

25 ppm of Cl = 25 g/ 1000 Kg

we know that 1Kg = 1L  that's why 1000 Kg = 1000 L

25 ppm of Cl = 25 g /1000 L

25 ppm = 0.025 g/ L

0.025 g could be written in term of Kg as follow,

0.025 × 1000  = 25 mg

25 ppm = 25 mg / L