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Analysis of Barium Nitrate (Ba(NO₃)₂)

Class 12 Chemistry Practical

How to do salt analysis · Viva · Quiz

Aim

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

Preliminary Test

ExperimentObservationInference
Physical examinationWhite crystalline solid; odourlessNot copper
SolubilitySoluble in waterNitrate
Dry heatingCrackling possible; brown fumes of NO₂; residue related to BaONitrate of an alkaline earth
Flame testApple-green flameBa²⁺
Dilute H₂SO₄White ppt of BaSO₄; no CO₂Not carbonate; sulphate forms from the acid
Conc. H₂SO₄ + CuBrown NO₂ fumesNO₃⁻ may be present

Test of Anion (NO₃⁻)

ExperimentObservationInference
Heat the salt with conc. H₂SO₄ and copper turningsBrown fumes of NO₂; solution often turns blue with CuNO₃⁻ may be present
Confirmatory Test
Brown ring
To 1 mL of the solution add freshly prepared FeSO₄, then pour conc. H₂SO₄ slowly down the side		Brown ring at the junction of the two layers (nitroso-ferrous sulphate)NO₃⁻ is confirmed

Ionic equations

  • 2NO₃⁻ + 4H₂SO₄ + 6Fe²⁺ → 2NO + 6Fe³⁺ + 4SO₄²⁻ + 4H₂O
  • FeSO₄ + NO → [Fe(H₂O)₅NO]SO₄ (brown ring)

Test of Cation (Ba²⁺)

ExperimentObservationInference
Groups I-IV reagents (dil. HCl, H₂S / acid, NH₄Cl + NH₄OH, H₂S / alkaline) give no pptNo precipitate in Groups I-IVGroups I-IV cations are absent
To the ammoniacal solution add (NH₄)₂CO₃White ppt of BaCO₃Group V may be present
Confirmatory Tests
Flame test
Flame test of the salt moistened with conc. HCl		Apple-green flameBa²⁺ is confirmed
Potassium chromate
Dissolve the carbonate ppt in acetic acid and add K₂CrO₄		Yellow ppt of BaCrO₄Ba²⁺ is confirmed

Ionic equations

  • Ba²⁺ + CrO₄²⁻ → BaCrO₄ ↓

Result

The given salt contains Ba²⁺ as the cation (basic radical) and NO₃⁻ as the anion (acidic radical). The salt is Barium Nitrate (Ba(NO₃)₂).

Precautions

  1. Use small quantities of salt and reagents; do not use excess.
  2. Keep the mouth of the test tube away from the face while heating.
  3. Use freshly prepared FeSO₄ for the brown ring test.
  4. Nessler’s reagent is toxic (mercury); handle with care and do not pipette by mouth.

Viva voce

  1. Why apple-green and brown ring together?

    Cation Ba²⁺, anion NO₃⁻.

  2. Why brown fumes on heating?

    Decomposition of nitrate to NO₂.

  3. Why BaSO₄ with dilute H₂SO₄?

    Barium salts + sulphate ions ppt BaSO₄. Not a carbonate test.

  4. Why K₂CrO₄?

    Confirmatory for barium in Group V.

  5. Why freshly prepared FeSO₄?

    Brown ring fails with oxidised ferrous sulphate.

  6. Flame wire?

    Conc. HCl, non-luminous flame, clean nichrome / platinum.

  7. Group?

    V.

  8. Difference from BaCl₂?

    Anion tests: brown ring vs chloride tests.

Related salts