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Analysis of Sodium Oxalate (Na₂C₂O₄)

Qualitative analysis

Aim

To analyse the given inorganic salt for one acidic and one basic radical.

Preliminary Test

  • Colour: White
  • Odour: Odourless
  • State: Crystalline solid
  • Solubility: Soluble in water

Test of Anion (C₂O₄²⁻)

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 (Na⁺)

ExperimentObservationInference
Flame test in a clean non-luminous flameIntense yellow flameNa⁺ may be present
Confirmatory Test
Zinc Uranyl Acetate Test
Take a filtrate and add zinc uranyl acetate solution
Yellow crystalline precipitateNa⁺ is confirmed

Result

The given salt contains Na⁺ as the cation (basic radical) and C₂O₄²⁻ as the anion (acidic radical). The salt is Sodium Oxalate (Na₂C₂O₄).

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.