VKC ScienceChemistry for written exams Telegram

UPSC Combined Geo-Scientist

Chemist

  • 3 descriptive papers
  • 200 marks each
  • 3 h per paper

Mains Paper I covers inorganic chemistry.

UPSC Combined Geo-Scientist, Mains · 2022 · Mains Paper I

Q8(c). Metal-ion indicators in EDTA titrations

Question

Explain the metal ion-indicator-EDTA reactions. What are the important criteria to be satisfied by metal ion indicator for visual detection of end points?

Answer in brief

The indicator forms a coloured metal complex. Near equivalence EDTA displaces the indicator, exposing its contrasting free colour; the metal-EDTA complex must be sufficiently more stable.

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.

See what is included Already a member? Sign in

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.

The handwritten model answer pages open with the VKC plan.
Read the whole 2022 solution2022 question paper

Topic notes: EDTA titrations, metal-ion indicators and masking, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversmetallochromic indicatorEriochrome Black TEDTA titration end pointmetal ion indicator criteria

All parts of Question 8