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Experiment No. N

Analysis of Iron(III) Oxalate ((Fe)₂(C₂O₄)₃)

Aim

To determine the presence of anion and cation in the given salt

Preliminary Test

  • Odor: Odorless
  • Texture: Crystalline
  • Color: White
  • Solubility: Slightly soluble in water

Test of Anion

ExperimentObservationInference
Take 0.1 g salt and add conc. H₂SO₄Colourless gases are evolved. On testing further, CO₂ and CO are evolvedC₂O₄²⁻ may be present
Confirmatory Tests
Calcium Chloride Test
Acidify extract with acetic acid and add calcium chloride		White precipitate of calcium oxalate is obtainedC₂O₄²⁻ is confirmed
KMnO₄ Test
Filter and add dilute H₂SO₄ to the precipitate, then dilute KMnO₄ and warm		KMnO₄ pink colour is dischargedC₂O₄²⁻ is confirmed

Test of Cation

ExperimentObservationInference
Original solution + NH₄OH solutionReddish-brown precipitateGroup-III cation may be present
Confirmatory Tests
Potassium Ferrocyanide Test
Dissolve the precipitate in dilute HCl, divide into two parts and add potassium ferrocyanide to one part		Blue/Prussian blue precipitateFe³⁺ is confirmed
Potassium Thiocyanate Test
To second part add potassium thiocyanate solution		Blood-red colouration is formedFe³⁺ is confirmed

Result

The given salt contains Fe³⁺ ions as cation and C₂O₄²⁻ ions as anion. The salt is (Fe)₂(C₂O₄)₃.

Precautions

  1. Handle the chemicals with care.
  2. Don't use excess of chemicals.
  3. Keep the mouth of the test tube away from the face.