Water hardness by EDTA titration
EDTA binds Ca²⁺ and Mg²⁺ one-to-one. With Eriochrome Black T the flask stays wine red while free metal remains, then snaps to blue at the endpoint.
EDTA binds Ca²⁺ and Mg²⁺ one-to-one. With Eriochrome Black T the flask stays wine red while free metal remains, then snaps to blue at the endpoint.