Question

Based on your titration of the 150ppm standard solution of Ca2+ calculate the molarity of the EDTA solution we used, which is

Ca2+ + EDTA4- ----> [CA(EDTA)]2-

Answer 1

IF your equation is correct (and I don't think it is) then 150 ppm is 150 mg/L or 0.150 g/L = (0.150/atomic mass Ca) mols/L = approx 0.00375M.

Then M standard soln x mL = ? millimoles.
mmols EDTA = twice that
M EDTA = mmols/mL.
I was under the impression that EDTA complexed almost all metals 1:1