Treatment of a 0.2500-g sample of impure potassium chloride with an excess of AgNO3 resulted in the for- mation of 0.2912 g of AgCl. Calculate the percentage of KCl in the sample.

Answer 1

KCl + AgNO3 ==> AgCl + KNO3
mols AgCl formed = g/molar mass = 0.2912/143.34 = 0.0020315
The ratio of KCl to AgCl is 1:1; therefore, mols KCl to start must be 0.0020315. Grams KCl = mols KCl x molar mass KCl = ?
% KCl = (grams KCl/mass sample)*100 = ?
Post your work if you get stuck. Check those molar mass and calculations. I tried to do that from memory.

Answer 2

0.0020315*74.5513 = 0.1513
% = 0.1513/0.2500 * 100 =60.52