Why is PbCl₂ only slightly soluble?

It is the Group I chloride. Hot water dissolves it; it re-ppts on cooling.

AgNO₃ on a lead chloride salt?

Still positive for Cl⁻ on the soda extract. Cation tests use dilute HCl / KI / chromate.

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Class 12 Chemistry Practical

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

Experiment	Observation	Inference
Physical examination	White solid; odourless	Not acetate
Solubility	Sparingly soluble in cold water; soluble in hot water	Characteristic of PbCl₂
Dry heating	May melt; no sublimate of NH₄Cl; no brown NO₂	Not ammonium chloride / lead nitrate
Dilute H₂SO₄	White ppt of PbSO₄ may form; no CO₂	Not carbonate
Conc. H₂SO₄	HCl gas (from chloride) on heating	Cl⁻ may be present
Flame test	No apple-green / brick-red	Not Ba / Ca

Experiment	Observation	Inference
Heat a pinch of salt with conc. H₂SO₄	Colourless gas with a pungent smell; dense white fumes with NH₄OH	Cl⁻ may be present
Confirmatory Tests
MnO₂ / conc. H₂SO₄ Heat the salt with conc. H₂SO₄ and a pinch of MnO₂	Greenish-yellow chlorine gas is evolved	Cl⁻ is indicated
Silver nitrate Acidify the soda extract with dilute HNO₃ and add AgNO₃, then NH₄OH	Curdy white ppt of AgCl, soluble in NH₄OH, reappears with dilute HNO₃	Cl⁻ is confirmed
Chromyl chloride Heat salt + K₂Cr₂O₇ + conc. H₂SO₄. Pass vapours into NaOH; acidify with acetic acid and add lead acetate	Yellow chromyl chloride vapours; yellow ppt of PbCrO₄	Cl⁻ is confirmed (chromyl chloride test)

Experiment	Observation	Inference
To the original solution add dilute HCl	White ppt of PbCl₂, soluble in hot water, reappears on cooling	Group I (Pb²⁺) may be present
Confirmatory Tests
Potassium iodide To the hot solution of the ppt add KI	Yellow ppt of PbI₂ (golden spangles on cooling)	Pb²⁺ is confirmed
Potassium chromate To the acidified solution add K₂CrO₄	Yellow ppt of PbCrO₄, insoluble in acetic acid	Pb²⁺ is confirmed

The given salt contains Pb²⁺ as the cation (basic radical) and Cl⁻ as the anion (acidic radical). The salt is Lead Chloride (PbCl₂).

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

Why dissolve in hot water?
Solubility of PbCl₂ rises sharply with temperature.
Why golden spangles with KI?
PbI₂ crystallises as shining yellow plates.
Why chromyl chloride can still work?
The salt contains chloride.
How is this different from NH₄Cl?
No ammoniacal smell, no sublimation, Group I lead tests instead of Nessler.
Why might original solution be made in hot water?
Cold water does not dissolve enough PbCl₂.
Why yellow with chromate?
PbCrO₄.
Why not Group II after this?
Lead is already confirmed in Group I (though Pb²⁺ can also ppt as PbS later if missed).
Is the formula Pb(Cl)₂?
No. Write PbCl₂.