Principles Related to Practical Chemistry – JEE Main Formula Sheet & Class 12 Notes | Qualitative & Quantitative Analysis

Qualitative Analysis — Preliminary Tests and Flame Test in Practical Chemistry

Why Preliminary Tests and Flame Colours Are Direct JEE Main One-Mark Questions on Practical Chemistry

Qualitative analysis in practical chemistry begins with preliminary observations before any reagents are added. These preliminary tests in practical chemistry provide immediate clues about which cation and anion are present in the salt.

Colour of the salt (preliminary test in practical chemistry): White salts — carbonates, sulphates, chlorides, nitrates of most metals. Coloured salts indicate transition metal ions: CuSO₄ (blue — Cu²⁺), FeSO₄ (light green — Fe²⁺), Fe₂(SO₄)₃ (yellow — Fe³⁺), MnSO₄ (light pink — Mn²⁺), NiSO₄ (green — Ni²⁺), CoCl₂ (blue anhydrous, pink hydrated — Co²⁺), K₂Cr₂O₇ (orange — Cr⁶⁺), KMnO₄ (purple — Mn⁷⁺).

Dry heating test in practical chemistry: Heating a small quantity of the salt in a dry test tube — observe colour change, gas evolution, residue colour. Carbonates: CuCO₃ → CuO (black residue) + CO₂; ZnCO₃ → ZnO (yellow hot, white cold). Nitrates (preliminary test — practical chemistry): Cu(NO₃)₂ → CuO (black) + NO₂ (brown) + O₂; Pb(NO₃)₂ → PbO (yellow) + NO₂ + O₂; AgNO₃ → Ag (grey) + NO₂ + O₂; Ba(NO₃)₂, NaNO₃ → nitrite + O₂ (no coloured gas). Sulphates of heavy metals decompose on strong heating to give SO₃.

Flame test in practical chemistry for cation identification: Na → golden yellow (the most intense, persistent flame colour in practical chemistry); Li → crimson red; K → lilac/violet (seen through blue cobalt glass to mask Na); Ca → brick red; Sr → crimson red (deeper than Li); Ba → apple green; Cu → blue-green or emerald green; Pb → greyish blue. The flame test in practical chemistry is performed by dipping a platinum wire in the salt and holding it in the flame. Download the Free PDF for practical chemistry principles including the complete flame test colour table for JEE Main.

Systematic Cation Analysis — Group Separation in Practical Chemistry

Why Systematic Cation Group Analysis Is a Must-Know Practical Chemistry Framework for JEE Main

The systematic qualitative analysis of cations in practical chemistry divides cations into six groups based on their behaviour with specific group reagents added in sequence. This systematic analysis of cations in practical chemistry is the backbone of inorganic salt analysis in JEE Main and board exams.

Group I cations in practical chemistry (group reagent: dil. HCl): Pb²⁺, Ag⁺, Hg₂²⁺ — precipitate as white chlorides (PbCl₂, AgCl, Hg₂Cl₂). PbCl₂ dissolves in hot water (distinguishes Pb²⁺ from Ag⁺ and Hg₂²⁺). AgCl dissolves in NH₃ solution (forms [Ag(NH₃)₂]⁺ — a coordination compound). Hg₂Cl₂ turns black with NH₃ (disproportionation: Hg₂Cl₂ + 2NH₃ → Hg + HgNH₂Cl + NH₄Cl).

Group II cations in practical chemistry (group reagent: H₂S in acidic medium, dilute HCl): Cu²⁺, Pb²⁺ (if passed Group I), Bi³⁺, Cd²⁺, As³⁺, Sb³⁺, Sn²⁺ — precipitate as coloured sulphides. CuS (black), PbS (black), Bi₂S₃ (black), CdS (yellow — JEE Main favourite), As₂S₃ (yellow), Sb₂S₃ (orange), SnS (dark brown). Subgroup IIA (not soluble in yellow ammonium sulphide — Cu²⁺, Pb²⁺, Bi³⁺, Cd²⁺). Subgroup IIB (soluble in yellow ammonium sulphide — As, Sb, Sn).

Group III cations in practical chemistry (group reagent: NH₄OH + NH₄Cl buffer to maintain pH ~9): Fe³⁺, Al³⁺, Cr³⁺ — precipitate as hydroxides. Fe(OH)₃ (reddish brown), Al(OH)₃ (white gelatinous), Cr(OH)₃ (greyish green). Confirmatory test in practical chemistry for Fe³⁺: potassium thiocyanate gives blood red [Fe(SCN)]²⁺. For Al³⁺: lake test — Al(OH)₃ + litmus/aluminom gives bright red-pink lake. For Cr³⁺: fusion with Na₂O₂ gives CrO₄²⁻ (yellow), confirmed by lead acetate giving yellow PbCrO₄ precipitate.

Group IV cations in practical chemistry (group reagent: H₂S in NH₄OH, alkaline medium): Zn²⁺, Mn²⁺, Co²⁺, Ni²⁺ — precipitate as sulphides. ZnS (white), MnS (buff/salmon pink), CoS (black), NiS (black). Confirmatory test for Zn²⁺: white precipitate ZnS dissolves in HCl; zinc is confirmed by blue-white ring in cobalt nitrate test. For Mn²⁺: pink precipitate MnS; confirmatory — Mn²⁺ + NaBiO₃ (sodium bismuthate) + dil. HNO₃ → MnO₄⁻ (pink-violet). For Co²⁺: in ammonium thiocyanate + acetone → intense blue [Co(SCN)₄]²⁻ (distinguishes from Ni²⁺). For Ni²⁺: Dimethylglyoxime (DMG) + Ni²⁺ in NH₃ → bright red precipitate (Ni-DMG chelate).

Group V cations in practical chemistry (group reagent: (NH₄)₂CO₃ in NH₄OH): Ba²⁺, Sr²⁺, Ca²⁺ — precipitate as white carbonates. Confirmed by flame test — Ba (green), Sr (crimson), Ca (brick red). BaSO₄ is insoluble in HCl (confirmed by H₂SO₄ giving white BaSO₄ precipitate). SrSO₄ sparingly soluble. CaSO₄ soluble in excess water (slight solubility).

Group VI cations in practical chemistry (no group reagent — remain in solution after Groups I–V): Na⁺, K⁺, NH₄⁺ — confirmed by specific tests. NH₄⁺: warm with NaOH → NH₃ gas (turns moist red litmus blue, or gives white fumes with HCl, or gives brown precipitate with Nessler's reagent — K₂[HgI₄] in KOH: 2K₂HgI₄ + NH₃ + 3KOH → Hg₂NI·H₂O↓(brown) + 7KI + 2H₂O). Na⁺: yellow flame; confirmed by zinc uranyl acetate reagent giving yellow precipitate. K⁺: lilac flame; confirmed by platinic chloride giving yellow precipitate or cobalt nitrite giving yellow precipitate [K₂Na[Co(NO₂)₆]] (sodium cobaltnitrite test). Download the Free PDF for the complete systematic cation analysis chart for practical chemistry JEE Main.

Anion Identification in Practical Chemistry — Systematic Tests for JEE Main

Why Anion Identification Tests in Practical Chemistry Are Direct JEE Main One-Mark Questions

Anion analysis in practical chemistry is less systematic than cation analysis but equally important for JEE Main. The anions are identified through their reaction with dilute H₂SO₄ (dilute acid test in practical chemistry), concentrated H₂SO₄ (concentrated acid test), and specific confirmatory reagents.

Dilute H₂SO₄ test in practical chemistry (anion analysis): CO₃²⁻: brisk effervescence of colourless CO₂ (turns lime water milky). SO₃²⁻: pungent smell of SO₂ (turns acidified K₂Cr₂O₇ green). S²⁻: rotten egg smell of H₂S (blackens lead acetate paper). NO₂⁻: pale yellow gas and blue colour with starch-iodide paper (evolution of NO₂ and NO). CH₃COO⁻ (acetate): vinegar smell of CH₃COOH.

Concentrated H₂SO₄ test in practical chemistry (anion analysis): Cl⁻: HCl gas (pungent, white fumes with NH₃, turns moist blue litmus red). Br⁻: HBr + Br₂ (reddish brown bromine fumes — more reducing than Cl⁻, reduces H₂SO₄ to SO₂). I⁻: HI + I₂ (violet iodine fumes — strongest reductant of halides, also gives H₂S and H₂S₂O₃). NO₃⁻: brown NO₂ gas (HNO₃ produced, decomposes to NO₂ in hot conc. H₂SO₄; also Cu + H₂SO₄ + NO₃⁻ → blue solution + brown fumes).

Confirmatory tests for specific anions in practical chemistry: SO₄²⁻: add BaCl₂ in dil. HCl → white BaSO₄ precipitate insoluble in HCl (distinguish from BaSO₃ which dissolves in HCl). Cl⁻: add AgNO₃ → white AgCl precipitate, soluble in NH₃. Br⁻: add AgNO₃ → pale yellow AgBr precipitate, slightly soluble in NH₃ (solubility in NH₃: AgCl > AgBr > AgI). I⁻: add AgNO₃ → yellow AgI precipitate, insoluble in NH₃. Confirm halides with chloroform and fresh Cl₂ water — Br⁻ → orange CHCl₃ layer; I⁻ → violet CHCl₃ layer. NO₃⁻ — brown ring test in practical chemistry: dilute solution in FeSO₄, pour conc. H₂SO₄ carefully — brown ring at junction due to [Fe(H₂O)₅NO]²⁺ complex (nitrosonium ferrous complex). PO₄³⁻: add ammonium molybdate in HNO₃ → yellow precipitate (ammonium phosphomolybdate). C₂O₄²⁻ (oxalate): dissolves BaSO₄ in acidified solution; in HCl gives CO₂ + CO with conc. H₂SO₄; confirmed by CaCl₂ → white CaC₂O₄ (insoluble in CH₃COOH). Download the Free PDF for the complete anion identification test chart for practical chemistry JEE Main.

Acid-Base Titrations in Practical Chemistry — Indicators, Formula, and Calculations

Why Titration Principles and the N₁V₁ = N₂V₂ Formula Are Core JEE Main Practical Chemistry Content

Acid-base titrations in practical chemistry (also called acidimetry and alkalimetry) involve neutralisation reactions between acids and bases. The key formula for all titration calculations in practical chemistry is: N₁V₁ = N₂V₂ (at the equivalence point, the milliequivalents of acid = milliequivalents of base). Here N = normality (equivalents per litre) and V = volume in mL or L (must be consistent). This formula is the foundation of all volumetric practical chemistry calculations in JEE Main.

Relationship between normality and molarity in practical chemistry: N = n × M, where n = n-factor (number of H⁺ ions donated per molecule for acid, or OH⁻ ions produced per molecule for base, or electrons transferred per molecule for redox). For HCl: N = M (n=1). For H₂SO₄: N = 2M (n=2). For H₃PO₄: N = 3M for triprotic titration (n=3). For NaOH: N = M (n=1). For Ca(OH)₂: N = 2M (n=2). For Na₂CO₃ (titrated against strong acid to give NaCl + H₂O + CO₂): n = 2, so N = 2M. For NaHCO₃ (titrated against strong acid): n = 1, so N = M.

Indicators in practical chemistry acid-base titrations: The choice of indicator depends on the nature of the salt formed at equivalence point. Strong acid + Strong base (e.g., HCl + NaOH) → neutral salt → use any indicator — phenolphthalein (range pH 8.3–10, colourless → pink) or methyl orange (range pH 3.1–4.4, red → yellow). Strong acid + Weak base (e.g., HCl + NH₄OH) → acidic salt → equivalence point pH < 7 → use methyl orange (changes in acidic range). Weak acid + Strong base (e.g., CH₃COOH + NaOH) → basic salt → equivalence point pH > 7 → use phenolphthalein (changes in basic range). Weak acid + Weak base → cannot be titrated accurately with simple indicators (equivalence point not sharp). Back titration in practical chemistry: used when the analyte is insoluble or reacts too slowly for direct titration. An excess of known reagent is added, the reaction is allowed to complete, and the excess is titrated back.

Calculations in practical chemistry JEE Main: Using N₁V₁ = N₂V₂: if 25 mL of H₂SO₄ solution is neutralised by 30 mL of 0.1 N NaOH, then: N(H₂SO₄) × 25 = 0.1 × 30 → N(H₂SO₄) = 3/25 = 0.12 N → M(H₂SO₄) = 0.12/2 = 0.06 M. Download the Free PDF for practical chemistry titration formula examples and n-factor calculations for JEE Main.

Redox Titrations in Practical Chemistry — KMnO₄ and K₂Cr₂O₇

Why Redox Titration Principles Are High-Frequency JEE Main Practical Chemistry Questions

Redox titrations in practical chemistry involve oxidation-reduction reactions where electrons are transferred. The n-factor for redox reactions in practical chemistry = number of electrons transferred per formula unit (change in oxidation state × number of atoms involved). Equivalents = moles × n-factor. At equivalence point: meq of oxidant = meq of reductant.

KMnO₄ titration in practical chemistry (permanganometry): KMnO₄ is a self-indicator — no external indicator needed (KMnO₄ is intense purple; endpoint = faint pink persisting for 30 seconds). In acidic medium (dil. H₂SO₄ always preferred in permanganometry — HCl oxidised by KMnO₄, HNO₃ itself is oxidising agent): MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O → n-factor for KMnO₄ in acidic medium = 5. Key reactions in acidic KMnO₄ titration in practical chemistry JEE Main: titration of oxalate (C₂O₄²⁻ → CO₂, n-factor = 2 per oxalate since each C goes from +3 to +4 = 2e⁻ per C, 4e⁻ total per C₂O₄²⁻... actually 2 carbons each go from +3 to +4 → 2e⁻ × 2 C = 2e⁻ total per oxalate? No — oxalate: C is +3, CO₂ C is +4, so each C loses 1e⁻, 2 C atoms → 2e⁻ per oxalate, n-factor = 2); titration of Fe²⁺ to Fe³⁺ (n-factor Fe²⁺ = 1); titration of H₂O₂ to O₂ (O is –1 → 0, 2 O → 2e⁻ per H₂O₂ molecule, n-factor H₂O₂ = 2).

K₂Cr₂O₇ titration in practical chemistry (dichromatometry): n-factor for K₂Cr₂O₇ = 6 (each Cr goes from +6 to +3 = 3e⁻ per Cr, 2 Cr atoms → 6e⁻ per Cr₂O₇²⁻). K₂Cr₂O₇ is NOT a self-indicator — requires an external redox indicator such as diphenylamine (changes from colourless to violet at endpoint) or N-phenylanthranilic acid. Advantage of K₂Cr₂O₇ over KMnO₄ in practical chemistry: it is a primary standard (can be accurately weighed to make standard solutions directly; KMnO₄ is not a primary standard — absorbs moisture and reacts with organic matter). Titration of Fe²⁺ with K₂Cr₂O₇ in practical chemistry: Cr₂O₇²⁻ + 14H⁺ + 6Fe²⁺ → 2Cr³⁺ + 6Fe³⁺ + 7H₂O. Download the Free PDF for redox titration calculations and n-factor tables in practical chemistry JEE Main.

Iodometric and Iodimetric Titrations in Practical Chemistry

Why Iodo-Titrations Are a Unique Practical Chemistry Section Tested in JEE Main

Iodine-based titrations in practical chemistry are divided into two types based on the role of iodine. Understanding the difference between iodometric and iodimetric titrations is a direct JEE Main practical chemistry question.

Iodometric titrations in practical chemistry (indirect method): An oxidising agent liberates iodine from excess KI solution in acidic medium. The liberated I₂ is then titrated against standard Na₂S₂O₃ (sodium thiosulphate) solution using starch solution as indicator (starch + I₂ → blue-black complex; endpoint = blue-black to colourless). The oxidising agent is indirectly estimated. Examples in practical chemistry JEE Main: CuSO₄ + KI → Cu₂I₂ (white ppt) + I₂ liberated → Na₂S₂O₃ titration: 2Cu²⁺ + 4I⁻ → Cu₂I₂ + I₂; I₂ + 2S₂O₃²⁻ → 2I⁻ + S₄O₆²⁻. K₂Cr₂O₇ + KI + H₂SO₄ → Cr³⁺ + I₂; I₂ titrated with Na₂S₂O₃. KMnO₄ + KI + H₂SO₄ → Mn²⁺ + I₂; I₂ titrated with Na₂S₂O₃. H₂O₂ + KI + H₂SO₄ → I₂ + H₂O; I₂ with Na₂S₂O₃.

Iodimetric titrations in practical chemistry (direct method): The analyte (a reducing agent) is titrated directly with standard I₂ solution. I₂ is the titrant and is used directly. The starch indicator turns blue-black at the endpoint (first excess I₂). Examples: Na₂S₂O₃ (sodium thiosulphate) titrated with I₂: 2S₂O₃²⁻ + I₂ → S₄O₆²⁻ + 2I⁻ (thiosulphate is oxidised to tetrathionate). Ascorbic acid (Vitamin C) titrated directly with I₂. Na₂SO₃ titrated with I₂. Distinction in practical chemistry: iodometry = iodine liberated then titrated with Na₂S₂O₃ (oxidising agent estimated); iodimetry = direct titration with I₂ (reducing agent estimated). Download the Free PDF for all iodometric and iodimetric reactions with balanced equations for practical chemistry JEE Main.

Lassaigne's Sodium Fusion Test — Detection of N, S, Halogens in Organic Compounds

Why Lassaigne's Test Reactions Are Direct JEE Main Practical Chemistry Formula Questions

Lassaigne's sodium fusion test (also called sodium fusion extract or sodium extract) is used in practical chemistry to detect the presence of nitrogen, sulphur, and halogens in organic compounds. The organic compound is fused with sodium metal in a dry ignition tube — sodium converts the organic elements into water-soluble ionic compounds that can be detected by standard inorganic tests. This is the starting point of all organic qualitative analysis in practical chemistry JEE Main.

Principle of Lassaigne's test in practical chemistry: Organic compound + Na (excess) → Na + organic C, H, N, S, halogen → NaCN (from N), Na₂S (from S), NaX (from halogen X). The fused mass is extracted with distilled water to give the sodium fusion extract (Lassaigne's extract). Tests on the sodium fusion extract in practical chemistry:

Test for nitrogen (Lassaigne's test, practical chemistry): To the sodium extract, add FeSO₄ solution and boil. Add Fe₂(SO₄)₃ or FeCl₃ and acidify with dil. H₂SO₄. A Prussian blue or green precipitate/colour of Prussian blue (Fe₄[Fe(CN)₆]₃) confirms nitrogen. Reactions: Na + C + N → NaCN; NaCN + FeSO₄ → Fe(CN)₂; 3Fe(CN)₂ + 2Fe₂(SO₄)₃ → Fe₄[Fe(CN)₆]₃↓ (Prussian blue). If no precipitate but a blood red colour, the compound may contain nitrogen in a form like –NH₂.

Test for sulphur (Lassaigne's test, practical chemistry): Sodium extract + lead acetate solution → black precipitate of PbS confirms sulphur. Alternatively, sodium extract + sodium nitroprusside (Na₂[Fe(CN)₅NO]) → violet/purple colour confirms S²⁻ (most sensitive test for sulphur in practical chemistry JEE Main). Reaction: Na + S → Na₂S (in fusion); Na₂S + Pb(CH₃COO)₂ → PbS↓ (black) + 2CH₃COONa.

Test for halogens (Lassaigne's test, practical chemistry): Sodium extract acidified with dil. HNO₃ + AgNO₃ solution. White precipitate (AgCl, soluble in NH₃) = Cl; Pale yellow precipitate (AgBr, slightly soluble in NH₃) = Br; Yellow precipitate (AgI, insoluble in NH₃) = I. Special cases in practical chemistry: if both N and S are present → NaCNS (sodium thiocyanate) forms → extract must be boiled with dil. HNO₃ (to decompose CN⁻ and S²⁻) before adding AgNO₃ for halogen test. Download the Free PDF for all Lassaigne's test reactions and colour observations for practical chemistry JEE Main.

Detection of Functional Groups in Organic Compounds — Practical Chemistry Tests for JEE Main

Why Organic Functional Group Tests Are a Guaranteed Marks Section in Practical Chemistry JEE Main

After detecting elements (N, S, halogens by Lassaigne's test), practical chemistry proceeds to identify the functional group present in the organic compound. Each functional group gives a characteristic reaction with specific reagents in practical chemistry. These functional group tests in practical chemistry are direct one-mark questions in JEE Main and important descriptive answers in CBSE Class 12 boards.

Detection of unsaturation in organic compounds (practical chemistry): Baeyer's test — add 1% alkaline KMnO₄ solution (Baeyer's reagent) to the compound → immediate decolourisation of pink/purple colour = positive test for C=C (alkene) or C≡C (alkyne) double/triple bond. Used to distinguish alkanes (no decolourisation) from alkenes/alkynes (decolourisation). Bromine water test (alternative) — decolourisation of brown Br₂ water also confirms unsaturation in practical chemistry.

Detection of aldehyde functional group in practical chemistry: Fehling's test — add Fehling's solution A (CuSO₄) + Fehling's solution B (sodium potassium tartrate in NaOH) and warm → brick-red/orange-red precipitate of Cu₂O confirms aldehyde (RCHO). Ketones do NOT give Fehling's test (except methyl glyoxal and some α-hydroxy ketones). Tollens' test (silver mirror test) — add ammoniacal silver nitrate (Tollens' reagent, [Ag(NH₃)₂]⁺) and warm in water bath → silver mirror on inner surface of test tube confirms aldehyde (RCHO + 2[Ag(NH₃)₂]OH → RCOONH₄ + 2Ag↓ + 3NH₃ + H₂O). Formic acid (HCOOH) and formate also give Tollens' test (not typical aldehydes but contain –CHO group effectively). Schiff's base test — fuchsin-sulphurous acid (Schiff's reagent) turns pink/magenta with aliphatic aldehydes but not ketones (aromatic aldehydes sometimes give faint colour). 2,4-DNP test — 2,4-dinitrophenylhydrazine gives yellow-orange precipitate (2,4-DNP derivative) with both aldehydes and ketones — used to confirm carbonyl group (C=O) presence, not to distinguish aldehyde from ketone.

Detection of ketone functional group in practical chemistry: Ketones do NOT give Fehling's test or Tollens' test. They give positive 2,4-DNP test and sodium nitroprusside test. Legal's test for methyl ketones — sodium nitroprusside in NaOH → red colour with methyl ketones (CH₃CO–). Iodoform test in practical chemistry: compound + I₂ + NaOH → yellow precipitate of CHI₃ (iodoform, antiseptic smell). Positive iodoform test: CH₃CHO (acetaldehyde), CH₃COCH₃ (acetone), CH₃CH(OH)R (methyl secondary alcohols), CH₃OH (methanol does NOT give), C₂H₅OH (ethanol gives). Iodoform test identifies: CH₃CO– or CH₃CH(OH)– groups in practical chemistry.

Detection of carboxylic acid functional group in practical chemistry: Litmus test — turns blue litmus red (acidic). Sodium bicarbonate test — RCOOH + NaHCO₃ → RCOONa + H₂O + CO₂↑ (brisk effervescence — the most important test for –COOH, distinguishes from phenol which does NOT give CO₂ with NaHCO₃). Ester formation — RCOOH + ROH/H₂SO₄ → fruity smell. Carboxylic acids react with Na₂CO₃ and NaHCO₃; phenols react with Na₂CO₃ but NOT with NaHCO₃ — this distinction in practical chemistry is a JEE Main favourite.

Detection of phenol (–OH attached to benzene ring) in practical chemistry: FeCl₃ test — phenol + FeCl₃ solution → violet/purple colour (phenolate complex with Fe³⁺). Most phenols give violet; catechol gives dark green; resorcinol gives dark violet. Does NOT give CO₂ with NaHCO₃ (distinguishes phenol from carboxylic acid in practical chemistry). Bromine water test — phenol decolourises Br₂ water AND gives white precipitate of 2,4,6-tribromophenol (tri-substitution without catalyst — confirms activated aromatic ring).

Detection of primary alcohol (–OH aliphatic) in practical chemistry: Lucas test — ZnCl₂ + conc. HCl (Lucas reagent): 3° alcohol → immediate turbidity (3° carbocation forms instantly); 2° alcohol → turbidity in 5 minutes; 1° alcohol → no turbidity at room temperature (needs heat). Victor Meyer test in practical chemistry — distinguishes 1°, 2°, 3° alcohols by reaction with PCl₅ then AgNO₂ then FeCl₃: 1° → red (nitrous ester); 2° → blue; 3° → colourless (no reaction with AgNO₂). Ceric ammonium nitrate test — positive for all alcohols (red colour) — distinguishes OH-containing compounds from non-OH compounds.

Detection of amines in practical chemistry — Primary, Secondary, Tertiary: Litmus test: all amines turn red litmus blue (basic). Carbylamine (isocyanide) test in practical chemistry: 1° amine + CHCl₃ + alc. KOH → foul-smelling isocyanide (carbylamine). Positive only for primary amines (both aliphatic and aromatic) — 2° and 3° amines do NOT give carbylamine test. Hinsberg's test in practical chemistry: benzene sulphonyl chloride (C₆H₅SO₂Cl) + amine: 1° amine → sulphonamide soluble in NaOH; 2° amine → sulphonamide insoluble in NaOH; 3° amine → no reaction. Nitrous acid test in practical chemistry: 1° aliphatic amine → unstable diazonium salt → N₂↑ + alcohol; 1° aromatic amine → stable diazonium salt at 0–5°C (used in dye synthesis); 2° amine → yellow oily N-nitrosoamine; 3° amine → no reaction. Download the Free PDF for the complete organic functional group detection table for practical chemistry JEE Main.