Question: a sample is to be analyzed for its chloride content by the precipitation and weighing of silver chloride. what mass of the sample should be used so that the mass of the precipitate will be equal to the percent of chloride in the sample.

Question

How would you go about figuring that out?

Answer 1

How would you set up for the percent?
%Cl = [(Mass AgCl ppt)*(1 mol AgCl/molar mass AgCl)*(atomic mass Cl^-/1 mol Cl^-)/mass sample]*100 = ??
Now you want mass ppt to equal %Cl.
It looks confusing on the board but write it out on a sheet of paper and you will see it.
Solve the above equation for mass sample, then cancel mass ppt with percent Cl^- (mass ppt will be in the numerator and mass sample in the denominator and the number you get will be the mass of the sample to be used. I get something like 25 or so. Check my work.