Question

The quantity of Cl in a water supply is determined by titrating the sample with Ag^+ Ag^+ (aq) + Cl- (aq) rightarrow AgCI (s) How many grams of Cl- are in a sample of the water if 20.2 mL of 0.1M Ag^+ is needed to react with all the chloride in the sample? If the sample has a mass of 10 g, what percent Cl- does it contain?

Answer 1

A) 20.2 ml = 0.0202 L

No. of mole = molarity $\times$ volume of solution in liter

No. of mole of Ag⁺ = 0.1$\times$0.0202 = 0.00202 mole

According to reaction Ag⁺ and Cl^- react in equimolar proportion thus, to to react 0.00202 mole of Ag⁺ 0.00202 mole of Cl^- must be there

molar mass of Cl = 35.453gm/mole that mean 1 mole of Cl = 35.453 gm then 0.00202 mole Cl = 35.453$\times$0.00202 = 0.071615 gm of Cl

0.071615 gm of Cl in sample

B) 10 gm mass = 100%

then 0.071615 gm = 100$\times$0.071615/10 = 0.71615%

0.71615% of Cl^- in solution.