Q8(a). Conditional Fe(III)-EDTA stability
Write the formation constant (Kf) and conditional formation constant (K′f) for metal-EDTA complex. Calculate the conditional (effective) formation constant for Fe³⁺ in a solution of 0.10 M FeY⁻ at pH 4.00 and at pH = 1.00. (Given: Kf for FeY⁻ is 1.3 × 10²⁵; αY⁴⁻ at pH 4.00 is 3.8 × 10⁻⁹; αY⁴⁻ at pH 1.00 is 1.9 × 10⁻¹⁸)
Answer in brief
K′f = αY⁴⁻·Kf: at pH 4.00, 4.94 × 10¹⁶; at pH 1.00, 2.47 × 10⁷.
Part of VKC Basic
Read the key points and the full model answer with VKC Basic
VKC Basic (₹999 for 6 months) opens every solved answer, the notes, the handbook and the daily answer archive. Every Mains test series includes it.
The full model answer
As written for the answer booklet: the diagram carries the working, the lines stay short. Read here only; it is not offered as a download.
Coversconditional formation constantEDTA alpha fractionFe-EDTAmetal-EDTA stability constant
All parts of Question 8
- 8(a) Conditional Fe(III)-EDTA stability10 marks
- 8(b) Stepwise formation of diamminesilver(I)10 marks
- 8(c) Metal-ion indicators in EDTA titrations10 marks