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UPSC Combined Geo-Scientist

Chemist

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

Mains Paper III covers analytical and organic chemistry.

UPSC Combined Geo-Scientist, Mains · 2023 · Mains Paper III

Q4(b). Alumina in bauxite by EDTA back-titration

Question

Briefly outline the complexometric method for determining alumina content in a bauxite ore.

Answer in brief

Back-titration: Al³⁺, separated from Fe and Ti, is boiled with a measured excess of EDTA; the unused EDTA is titrated with standard Zn²⁺ at pH 5–5.5 (xylenol orange).

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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.

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Topic notes: analysis of ores, alloys, petroleum, coal and coke (dolomite, bauxite, brass, Ni in steel, aniline point, proximate and ultimate analysis, calorific value), with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversbauxite analysisEDTA back-titrationcomplexometric titrationalumina estimationxylenol orange

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