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Analysis of Barium Carbonate (BaCO₃)

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 (CO₃²⁻)

ExperimentObservationInference
Take 0.1 g of salt, add 1–2 mL of dilute H₂SO₄Colourless odourless gas is evolved with brisk effervescence; lime water turns milkyCO₃²⁻ may be present
Confirmatory Test
Lime Water Test
Pass the gas through lime water
Lime water turns milky; milkiness disappears on passing excess gas (soluble calcium bicarbonate)CO₃²⁻ 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 CO₃²⁻ as the anion (acidic radical). The salt is Barium Carbonate (BaCO₃).

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.