Calculate the mass of KCl that should be dissolved to form a 5 ppm Cl^- ion solution having a total volume of 20 dm^3?

1 Answer
Jul 17, 2015

The mass of KCl is 0.2 g.

Explanation:

"5 ppm" means "5 g of solute" in 10^6 "g of solution".

"Mass of soln" = 20 cancel("dm³ soln") × "1000 g soln"/(1 cancel("dm³ soln")) = "20 000 g soln"

"Mass of Cl"^(-) = 20 000 cancel("g soln") × ("5 g Cl"^-)/(10^6 cancel("g soln")) = "0.10 g Cl"^-

"Mass of KCl" = 0.10 cancel("g Cl⁻")× "74.55 g KCl"/(35.45cancel("g Cl⁻")) = "0.2 g KCl"