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Experiment No. N

Analysis of Calcium Sulfate (CaSO₄)

Aim

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

Preliminary Test

  • Odor: Odorless
  • Texture: Crystalline
  • Color: White
  • Solubility: Soluble in water

Test of Anion

ExperimentObservationInference
Confirmatory Tests
If no earlier anion test is positive, acidify the extract with dilute HCl and add BaCl₂ solutionWhite precipitate of barium sulphate, insoluble in conc. HCl or conc. HNO₃ is obtainedSO₄²⁻ may be present
Lead Acetate Test
Acidify the solution with acetic acid and add lead acetate solution		White precipitate appearsPresence of SO₄²⁻ is confirmed

Test of Cation

ExperimentObservationInference
Original solution + Dilute HClNo reactionGroup I cation is absent
Original solution + Dilute HCl + H₂S gas (with NH₄Cl)No reactionGroup II cation is absent
Original solution + Dilute HCl + NH₄Cl solid + NH₄OHNo reactionGroup III cation is absent
Original solution + NH₄Cl + NH₄OH + (NH₄)₂CO₃White precipitate is formedGroup V cation may be present
Confirmatory Test
Ammonium Oxalate Test
Dissolve white precipitate in dilute acetic acid and add ammonium oxalate solution		White precipitateCa²⁺ is confirmed

Result

The given salt contains Ca²⁺ ions as cation and SO₄²⁻ ions as anion. The salt is CaSO₄.

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.