Lead Acetate (Pb(CH₃COO)₂) Salt Analysis – CBSE Class 12

1. Preliminary Examination

• Appearance: White, crystalline solid, soluble in water.
• Flame Test: Faint bluish-white flame (not very distinct).

2. Dry Heating Test

• Observation: Decomposes with white fumes (acetic acid smell), black residue of lead oxide (PbO) remains.

3. Action with Dilute and Concentrated H₂SO₄

• With Dilute H₂SO₄: White ppt. of PbSO₄ formed (insoluble in water and acids).
• With Concentrated H₂SO₄: Similar reaction as dilute, more vigorous.

4. Confirmatory Tests for Pb²⁺ (Lead) – with Chemical Reactions

Test	Procedure	Observation	Inference	Chemical Reaction
Potassium Iodide (KI)	Add KI to salt solution.	Bright yellow ppt. of PbI₂	Pb²⁺ confirmed	Pb(CH₃COO)₂ + 2KI → PbI₂↓ (yellow) + 2CH₃COOK
Dilute H₂SO₄	Add dilute H₂SO₄ to salt solution.	White ppt. of PbSO₄	Pb²⁺ confirmed	Pb(CH₃COO)₂ + H₂SO₄ → PbSO₄↓ (white) + 2CH₃COOH
Potassium Chromate (K₂CrO₄)	Add K₂CrO₄ to salt solution.	Yellow ppt. of PbCrO₄	Pb²⁺ confirmed	Pb(CH₃COO)₂ + K₂CrO₄ → PbCrO₄↓ (yellow) + 2CH₃COOK
Ammonium Hydroxide (NH₄OH)	Add NH₄OH dropwise to salt solution.	White ppt. of Pb(OH)₂	Pb²⁺ confirmed	Pb(CH₃COO)₂ + 2NH₄OH → Pb(OH)₂↓ (white) + 2CH₃COONH₄
Dilute HCl (Group I test)	Add dilute HCl to salt solution (then heat).	White ppt. of PbCl₂ (soluble in hot water)	Pb²⁺ confirmed	Pb(CH₃COO)₂ + 2HCl → PbCl₂↓ (white, soluble in hot) + 2CH₃COOH

5. Tests for Anion (CH₃COO⁻: Acetate) – with Chemical Reactions

Test	Procedure	Observation	Inference	Chemical Reaction
Acetic Acid Odor Test	Warm salt with conc. H₂SO₄.	Pungent smell of vinegar (acetic acid vapors).	CH₃COO⁻ confirmed	Pb(CH₃COO)₂ + H₂SO₄ → PbSO₄ + 2CH₃COOH↑
Ferric Chloride (FeCl₃)	Add neutral FeCl₃ to salt solution.	Blood-red coloration (ferric acetate).	CH₃COO⁻ confirmed	6CH₃COO⁻ + 2Fe³⁺ → 2[Fe(CH₃COO)₃]
Ester (Fruity Smell) Test	Warm salt with ethanol and conc. H₂SO₄.	Fruity smell of ethyl acetate.	CH₃COO⁻ confirmed	CH₃COO⁻ + C₂H₅OH + H⁺ → CH₃COOC₂H₅ + H₂O

6. Summary of Identification

• Cation: Pb²⁺ (Lead)
• Anion: CH₃COO⁻ (Acetate)
• Salt: Pb(CH₃COO)₂ (Lead(II) acetate)

7. Key Points for Practical Exam

• Observe color and solubility of precipitates carefully.
• Write balanced chemical reactions for all confirmatory tests.
• Do not forget characteristic odors and solubility properties for acetate and lead compounds.

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