Chemistry Salt Analysis: Cation Groups (0 to VI)
| Group | Reagents | Cations | Asli Precipitate / Confirmation Test |
|---|---|---|---|
| Grp 0 | NaOH + Heat | NH₄⁺ | NH₃ gas gives brown ppt with Nessler’s Reagent [K₂HgI₄] |
| Grp I | Dilute HCl | Pb²⁺ | White PbCl₂ ppt (soluble in hot water; yellow with KI) |
| Grp II | H₂S gas in Dil HCl | Cu²⁺, As³⁺ | Black CuS (dissolves in HNO₃ to give deep blue with NH₄OH) |
| Grp III | NH₄OH + NH₄Cl | Fe³⁺, Al³⁺ | Red-brown Fe(OH)₃ (blood red with KSCN); White Al(OH)₃ |
| Grp IV | H₂S in NH₄OH | Zn²⁺, Mn²⁺, Ni²⁺, Co²⁺ | White ZnS; Flesh MnS; Black NiS (scarlet red with DMG) |
| Grp V | (NH₄)₂CO₃ + NH₄OH | Ba²⁺, Sr²⁺, Ca²⁺ | BaCrO₄ yellow; SrSO₄ white; CaC₂O₄ white |
| Grp VI | Na₂HPO₄ | Mg²⁺ | White crystalline ppt of Mg(NH₄)PO₄ |
Anion Confirmations & Flame Test Rang
| Anion | Preliminary Test | Confirmatory Test & Pakka Rang |
|---|---|---|
| CO₃²⁻ | Dil. H₂SO₄ → Brisk effervescence (CO₂) | Lime water turns milky; clears on excess CO₂ |
| S²⁻ | Dil. H₂SO₄ → Rotten egg smell (H₂S) | Lead acetate paper turns shiny black (PbS) |
| NO₂⁻ | Dil. H₂SO₄ → Pale blue liquid & brown gas | KI + starch solution turns deep blue |
| Cl⁻, Br⁻, I⁻ | Conc. H₂SO₄ + heat | Cl: White AgNO₃ ppt; Br: Pale yellow; I: Yellow insoluble |
| NO₃⁻ | Conc. H₂SO₄ + Cu turnings | Brown Ring Test: FeSO₄ + conc H₂SO₄ → [Fe(H₂O)₅(NO)]²⁺ |
| SO₄²⁻ | Aqueous solution + BaCl₂ | Thick white BaSO₄ ppt insoluble in conc. HCl |
Flame Colours: Ba²⁺ = Apple Green • Sr²⁺ = Crimson Red • Ca²⁺ = Brick Red • Cu²⁺ = Blue-Green
Experimental Physics Apparatus & Formulas
| Instrument | Key Formula / Principle | Least Count / Galti Ka Point |
|---|---|---|
| Vernier Caliper | Reading = MSR + (VSR × LC) Zero Error: Asli Reading = Observed − Error |
LC = 1 MSD − 1 VSD Typically 0.1 mm or 0.01 cm |
| Screw Gauge | Reading = Pitch Scale + (Circular Scale × LC) Pitch = Distance moved / No. of rotations |
LC = Pitch / Circular Scale Divisions Positive vs negative error dhyan se dekhna |
| Meter Bridge | Unknown Resistance X = R × (100 − l) / l Null point at l cm from left end |
End resistance correction at strips. Null point 40 cm – 60 cm ke beech rakho. |
| Resonance Tube | v = 2f × (l₂ − l₁) End correction: e = (l₂ − 3l₁) / 2 ≈ 0.3d |
Speed of sound in water level. l₁ = λ/4 − e, l₂ = 3λ/4 − e |
| Prism Spectrometer | Refractive index: μ = sin[(A + δm)/2] / sin[A/2] A = prism angle (typically 60°) |
Minimum deviation pe angle of incidence i = emergence e hota hai. |
| Convex Lens Focal Length | 1/f = 1/v − 1/u (Lens Formula) u-v graph rectangular hyperbola hai |
Parallax error object pin aur inverted real image pin ke beech hatana hota hai. |
Organic Functional Group Spot Tests
| Group | Reagent / Test | Asli Observation |
|---|---|---|
| Alcohol (-OH) | Ceric Ammonium Nitrate (CAN) | Red color complex formed instantly |
| Phenol (Ar-OH) | Neutral FeCl₃ solution | Violet / blue-green coloration |
| Aldehyde (-CHO) | Tollens’ Reagent [Ag(NH₃)₂]⁺ | Test tube ki deewar pe silver mirror ban jayega |
| Ketone (CH₃CO-) | I₂ + NaOH (Iodoform Test) | Yellow crystalline ppt of CHI₃ (antiseptic smell) |
| Carboxyl (-COOH) | Aqueous NaHCO₃ | CO₂ gas ki brisk effervescence niklegi |
| Primary Amine (-NH₂) | CHCl₃ + Alc. KOH (Carbylamine) | Extremely foul smell of Isocyanide (R-NC) |