A mixture contains Fe 2 + , Fe 3 + , and Cr 3 + . On treatment with NaOH: • Fe²⁺ → green ppt, oxidizes to brown • Fe³⁺ → brown ppt • Cr³⁺ → green ppt, soluble in excess NaOH Determine a sequence to se

Question

A mixture contains Fe 2 + , Fe 3 + , and Cr 3 + . On treatment with NaOH: • Fe²⁺ → green ppt, oxidizes to brown • Fe³⁺ → brown ppt • Cr³⁺ → green ppt, soluble in excess NaOH Determine a sequence to separate these three cations.

TestHub · Accepted Answer

Question Explanation:

Separation of transition metal cations using solubility.

Concept:

Separation of Group III Basic Radicals

Solution:

• Fe³⁺ forms a brown precipitate immediately, so it can be removed first.

• Fe²⁺ forms a green precipitate, which is oxidized later to Fe³⁺.

• Cr³⁺ forms a green precipitate, which is soluble in excess NaOH. It is removed last via selective complexation.

Final Answer: Fe³⁺ → Fe²⁺ → Cr³⁺

Chemistry - Salt Analysis Question with Solution | TestHub

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