Answer to Question #95046 in Organic Chemistry for Vijay Yadav

Question

Explain the theory of EDTA titration with supporting equation . Also give the structure of M-EDTA COMPLEX

Answer 1

Ethylenediaminetetraacetic acid, or EDTA, is an aminocarboxylic acid. EDTA is a Lewis acid with six binding sites—four negatively charged carboxylate groups and two tertiary amino groups—that can donate six pairs of electrons to a metal ion. The resulting metal–ligand complex is very stable. The actual number of coordination sites depends on the size of the metal ion, however, all metal–EDTA complexes have a 1:1 stoichiometry.

To illustrate the formation of a metal–EDTA complex, let’s consider the reaction between Cd2+ and EDTA: Cd²⁺(aq) + Y⁴⁻(aq) ⇌ CdY²⁻(aq), where Y^4– is a shorthand notation for the fully deprotonated form of EDTA.

References:

1.         Chemistry: LibreTexts [Electronic resource] : supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. - Mode of access: https://chem.libretexts.org/Bookshelves/Analytical_Chemistry/Book%3A_Analytical_Chemistry_2.0_(Harvey)/09_Titrimetric_Methods/9.3%3A_Complexation_Titrations. – Date of access: 22.09.2019.