Question

A 0.3146-g sample of a mixture of NaCl(s) and KBr(s) was dissolved in water. The resulting solution required 41.10 mL of 0.08765 M AgNO3(aq) to precipitate the Cl–(aq) and Br–(aq) as AgCl(s) and AgBr(s). Calculate the mass percentage of NaCl(s) in the mixture.

Answer 1

The molar masses of NaCl and KBr are 58.5 g/mol and 119.8 g/mol respectively.
Let the mass of NaCl in the mixture be x g. Mass of KBr will be 0.3146-x g
The number of moles of chloride ions and bromide ions will be and respectively
Total number of moles of chloride ions and bromide ions will be ......(1)
The resulting solution required 41.10 mL of 0.08765 M AgNO3(aq) to precipitate the Cl–(aq) and Br–(aq) as AgCl(s) and AgBr(s).
The number of moles of silver ions moles ....(2)
(1) = (2)

The mass percentage of NaCl(s) in the mixture is %