You are performing a method validation experiment using a potentiometric AgNO3 titration. A dried pure salt (MCl), where M is a +1 cation, is placed in the Erlenmeyer flask and the AgNO3 solution is placed in the burette. The reaction stoichiometry is as follows: MCl + AgNO3 -> AgCl + MNO3 If the mass of the salt is 0.111 grams and the endpoint of the titration is 21.21 mL and concentration of AgNO3 = 0.098 mol/L,

what is the %w/w Cl in the MCl salt?