For EDTA titrations the titration reaction is Mⁿ⁺ + EDTA ⇋ MY^n-4.Which statements are true for EDTA titration curves?
I At the equivalence point,there is exactly as much EDTA in solution as metal.[Mⁿ⁺] is calculated from the dissociation of MY^n-4 formed.
II After the equivalence point,the concentration free EDTA equals excess EDTA and virtually all metal ion is in the form MY^n-4.[Mⁿ⁺] is calculated from the dissociation of MY^n-4.
III Before the equivalence point,free [Mⁿ⁺] equals excess unreacted Mⁿ⁺ after EDTA has been consumed.Dissociation of MY^n-4 is negligible.
IV pM is plotted on the y-axis and milliliters EDTA solution added on the x-axis.

Question

Quizplus · Accepted Answer

EDTA titrations involve the complexation of metal ions by EDTA. At the equivalence point, the amount of EDTA added is stoichiometrically equivalent to the amount of metal ions present, making statement I true. After the equivalence point, the concentration of free EDTA equals the excess EDTA, with virtually all metal ions complexed by EDTA, making statement II true. Before the equivalence point, the concentration of free metal ions equals the excess unreacted metal ions, as the EDTA added has been fully complexed, making statement III true. The titration curve typically plots pM (negative logarithm of the metal ion concentration) against the volume of EDTA added, making statement IV true.

For EDTA Titrations the Titration Reaction Is Mn+ + EDTA

For EDTA Titrations the Titration Reaction Is Mⁿ⁺ + EDTA