Question

A solution is prepared by dissolving calcium chloride in water and diluting to 500.0 mL. If this solution contains 44 ppm chloride ions, the concentration of calcium ions is how many ppm?
a) 44
b) 88
c) 22
d) 11
e) 500

Answer 1

Answer:

The answer is c) 22 ppm

Explanation:

The dissolution of calcium chloride in water as below,

CaCl₂ ⇒ Ca²⁺ + 2Cl⁻

Clearly, in aqueous solution, the concentration of chloride ions always double the concentration of calcium ion. So, in our case, the chloride ions concentration is 44 ppm, the calcium ion will be 22 ppm.

ppm is part per million, which is based on the molecule concentration, so we can quickly use the molar stoichiometry ratio to find out the answer.