Question

A silver coin weighing 11.34 g was dissolved in nitric acid. When sodium chloride was added to the solution all the silver (present as AgNO₃) was precipitated as silver chloride. The weight of the precipitated silver chloride was 14.35 g. Calculate the percentage of silver in the coin - 

(A) 4.8 % 

(B) 95.2% 

(C) 90 % 

(D) 80%

Answer 1

Correct Answer is: (B) 95.2% 

Ag + 2HNO₃ → AgNO₃ + NO₂ + H₂O 108

AgNO₃ + NaCl → AgCl + NaNO₃ 143.5

∴ 143.5 gm of silver chloride would be precipitated by 108 g of silver.

or 14.35 g of silver chloride would be precipitated 10.8 g of silver.

∵ 11.34 g of silver coin contain 10.8 g of pure silver.

∴ 100 g of silver coin contain 10.8/11.34 x 100 = 95.2 %