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Analysis of Barium Sulfate (BaSO₄)

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: Insoluble in water

Test of Anion (SO₄²⁻)

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 (Ba²⁺)

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 ppt is formedGroup V cation may be present
Confirmatory Tests
Flame Test
Moisten the salt with conc. HCl and introduce it into a non-luminous flame on a platinum / nichrome wire
Apple-green flameBa²⁺ is confirmed
Potassium Chromate Test
Dissolve the white precipitate in dilute acetic acid and add potassium chromate
Yellow precipitate of barium chromateBa²⁺ is confirmed

Result

The given salt contains Ba²⁺ as the cation (basic radical) and SO₄²⁻ as the anion (acidic radical). The salt is Barium Sulfate (BaSO₄).

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.