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Experiment No. N

Analysis of Copper(II) Oxalate (CuC₂O₄)

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 + H₂S gas in presence of dil. HClBlack precipitate of Group-II A is formedGroup-II cation may be present
Confirmatory Test
Potassium Ferrocyanide Test
Dissolve the black precipitate in dilute nitric acid, boil the filtrate and then add potassium ferrocyanide		Chocolate brown precipitatePresence of Cu²⁺ is confirmed

Result

The given salt contains Cu²⁺ ions as cation and C₂O₄²⁻ ions as anion. The salt is CuC₂O₄.

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.