If I titrate a sample containing Ammonium Sulphide with a 0.05m Cadmium chloride until an end point is reached, how do I calculate the % sulphide in the sample
I will assume you don't know any better and wrote m when you intended to write M. m = molality; M = molarity. Big difference.
(NH4)2S + CdCl2 ==> CdS + 2NH4Cl
mols CdCl2 = M x L = ?
The equation tells you that 1 mol CdCl2 = 1 mol S.
g S = mols S x atomic mass S.
%S in sample = (g S/mass sample)*100 = ?