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Chemistry · L4 · EDTA Complexometric Titration
EDTA as a hexadentate 'claw' ligand forming an enormous-Kf 1:1 complex with metal ions, how a metal-ion indicator (Eriochrome Black T) gives a sharp visible endpoint, and a full worked calculation turning an EDTA titration into a quantitative water-hardness value in mg/L as CaCO3.