BSEH SS Chemistry study guide
BSEH SS Chemistry · Work through your exam, one topic at a time.
BSEH Senior Secondary Chemistry is the Class XII chemistry paper set by the Board of School Education, Haryana for candidates completing the senior secondary stage at affiliated schools. It is taken mainly by science-stream students - medical and non-medical - who need the subject for the school-leaving certificate, for university admission, and for eligibility in professional entrance examinations. The BSEH SS Chemistry study guide has 13 sections and about 3,991 words.
01Solid State and Solutions
This domain is examined as two linked numerical clusters: unit-cell and defect reasoning, then concentration and colligative-property calculations. fcc/ccp: Z = 4, coordination number 12, packing efficiency 74%, r = a/(2√2) bcc: Z = 2, CN 8, 68%, r = √3a/4 simple cubic: Z = 1, CN 6, 52.4% density d = ZM/(a³N A); convert pm to cm before substituting Schottky: a cation–anion pair is missing; density falls (NaCl, KCl) Frenkel: a cation moves to an interstitial site; density unchanged (AgCl, ZnS) F-centre: an electron trapped in an anion vacancy gives colour, e.g.
339 words, about 2 min02Electrochemistry
Electrochemistry questions combine cell EMF calculations, conductance relations, and applied cells such as lead storage and fuel cells. E°cell = E°cathode − E°anode, both written as reduction potentials ΔrG° = −nFE°cell and log K = nE°cell/0.0591 at 298 K Nernst equation: E = E° − (0.0591/n)·log Q, where Q uses products/reactants of the cell reaction κ = 1/ρ; molar conductivity Λm = 1000κ/c (S cm² mol⁻¹) strong electrolytes: Λm = Λ°m − A√c weak electrolytes: α = Λm/Λ°m and Ka = cα²/(1 − α); Λ°m comes from Kohlrausch's law of independent migration Dry cell: zinc anode, MnO2/carbon cathode, paste of NH4Cl and ZnCl2; not rechargeable Lead storage: Pb anode and PbO2 cathode in ~38% H2SO4; both plates become PbSO4 on discharge and are regenerated on charging H2–O2 fuel cell: high efficiency, product is only water Rusting needs both oxygen and water; iron acts as the anode and is oxidised For Zn Zn²⁺(0.10 M) Cu²⁺(0.010 M) Cu with E° = 1.10 V: n = 2, Q = [Zn²⁺]/[Cu²⁺] = 10.
303 words, about 2 min03Chemical Kinetics
Chemical Kinetics tests order determination, integrated rate laws, half-life, and Arrhenius reasoning. rate = k[A]^m[B]^n; order is experimental and is not read off the balanced equation molecularity belongs to an elementary step and is always a small whole number zero order: [A] = [A]0 − kt, t½ = [A]0/2k (depends on initial concentration) first order: k = (2.303/t)log(a/(a − x)), t½ = 0.693/k (independent of concentration) units of k: mol L⁻¹ s⁻¹ (zero), s⁻¹ (first), L mol⁻¹ s⁻¹ (second) k = A·e^(−Ea/RT); log(k2/k1) = Ea/2.303R × (1/T1 − 1/T2) a plot of log k against 1/T has slope −Ea/2.303R temperature coefficient is roughly 2–3 per 10 K for many reactions a catalyst lowers Ea and speeds both directions; it does not shift K or ΔH A first-order reaction is 75% complete in 60 min.
299 words, about 1 min04Surface Chemistry
Surface Chemistry covers adsorption isotherms, catalysis, and colloid behaviour, with the colloid part dominating objective questions. physisorption: van der Waals forces, ΔH about 20–40 kJ mol⁻¹, multilayer, reversible, decreases with temperature chemisorption: chemical bonding, ΔH about 80–240 kJ mol⁻¹, monolayer, often irreversible, needs activation energy Freundlich isotherm: x/m = k·p^(1/n) with 0 < 1/n < 1; a plot of log(x/m) against log p gives slope 1/n and intercept log k; the isotherm fails at high pressure Langmuir model assumes a saturated monolayer of identical sites homogeneous (same phase) versus heterogeneous (surface reaction) promoters increase activity (Mo in Fe for Haber); poisons destroy it (CO on Pt) enzymes are highly specific and work best at an optimum pH and temperature particle size 1–1000 nm; Brownian motion, Tyndall scattering, electrophoresis coagulation: Hardy–Schulze rule states that the ion carrying charge opposite to the sol is effective, and effectiveness rises steeply with its charge - Al³⁺ ≫ Ca²⁺ Na⁺ for a negative sol gold number measures protective power of a lyophilic colloid; a lower value means better protection dialysis removes crystalloids through a membrane, not the colloid As2S3 forms a negatively charged sol.
318 words, about 2 min05General Principles and Processes of Isolation of Elements
This domain tests the logic of the metallurgical flow sheet: concentrate, convert to oxide, reduce, then refine. froth flotation for sulphide ores, using pine oil or xanthate collectors magnetic separation for magnetic gangue such as Fe3O4 Bayer process for bauxite: hot NaOH dissolves alumina as Na[Al(OH)4]; Al(OH)3 is precipitated and calcined cyanide leaching for gold and silver, giving [Au(CN)2]⁻ roasting: sulphide to oxide in excess air, releasing SO2 calcination: carbonate or hydrated ore to oxide in limited air, releasing CO2 Ellingham diagrams plot ΔG° of oxide formation against temperature; a metal line lying below another oxide line can reduce it carbon reduces oxides above the temperature at which the C→CO line crosses the metal-oxide line; below that, CO is the better reductant thermite: Cr2O3 + 2Al → Al2O3 + 2Cr, strongly exothermic Hall–Héroult: Al2O3 in molten cryolite plus CaF2, carbon anodes; cryolite lowers the melting point and improves conductivity Mond process for nickel via Ni(CO)4; van Arkel for Ti and Zr via iodides zone refining for Si and Ge; liquation for Sn and Pb electrolytic refining of copper in acidified CuSO4 with pure copper cathodes and impure anodes; gold and silver collect as anode mud Zinc can be extracted from ZnO by carbon, but alumina cannot be reduced by carbon at practical temperatures, because the Al2O3 line in the Ellingham diagram lies far below the C→CO line, so aluminium oxide is far more stable and aluminium is won electrolytically instead.
361 words, about 2 min06p-Block Elements
p-Block questions focus on periodic trends, anomalous behaviour of the first member, and the shapes and oxoacids of the heavier elements. N2 is inert: triple bond, small size, no dipole NH3 is basic and hydrogen-bonded; HNO3 is a strong oxidiser white phosphorus (P4) is reactive and soluble in CS2; red phosphorus is polymeric and less reactive H3PO3 is dibasic while H3PO4 is tribasic NCl3 hydrolyses to NH3 and HOCl ozone is bent and diamagnetic, and liberates iodine from acidified KI (a quantitative estimation) H2O2 acts as oxidant and reductant; it titrates against acidified KMnO4 SO2 bleaches by reduction (temporary), Cl2 bleaches by oxidation H2SO4 is both an oxidising agent and a dehydrating agent; contact process gives it Cl2 with cold dilute NaOH gives NaCl and NaOCl; with hot concentrated NaOH it gives NaClO3 acid strength: HClO4 HClO3 HClO2 HOCl, because extra oxygen atoms delocalise and stabilise the conjugate base XeF2 is linear, XeF4 square planar, XeF6 a distorted octahedron inert pair effect stabilises lower oxidation states down groups: Tl(I), Pb(II), Bi(III) Comparing HOCl and HClO4: both have an O–Cl bond, but perchlorate has four oxygens.
313 words, about 2 min07d- and f-Block Elements and Coordination Compounds
This is the largest inorganic area: electronic configurations, magnetic and colour properties, and coordination compound structure, naming and isomerism. Cr is [Ar]3d⁵4s¹ and Cu is [Ar]3d¹⁰4s¹ (extra stability) variable oxidation states, catalytic activity, coloured ions, paramagnetism, alloy formation colour arises from d–d transitions; Sc³⁺ (d⁰) and Mn²⁺ (d⁵, high spin) are colourless or very pale magnetic moment μ = √(n(n+2)) BM for n unpaired electrons oxidation state x = total complex charge − sum of ligand charges CFSE and the spectrochemical series: CO ≈ CN⁻ en NH3 H2O F⁻ Cl⁻ strong-field ligands give low spin; tetrahedral complexes are essentially always high spin isomerism: geometrical (square planar and octahedral), optical, ionisation, hydrate, linkage (NO2⁻, SCN⁻) chelating ligands such as en give extra stability lanthanoid contraction makes Zr and Hf nearly identical in size and chemistry actinoids show more variable oxidation states and are radioactive [Fe(CN)6]³⁻: Fe is +3, so d⁵.
300 words, about 2 min08Haloalkanes and Haloarenes
Questions here turn on substitution versus elimination, SN1 versus SN2, and the special inertness of aryl halides. SN2: backside attack, second order, inversion of configuration, favoured by 1° halides and polar aprotic solvents SN1: carbocation intermediate, first order, racemisation, favoured by 3° halides and polar protic solvents SN1 reactivity: 3° 2° 1°; SN2 reactivity: 1° 2° 3° allyl and benzyl halides are fast by both routes; vinyl and aryl halides are inert Finkelstein: R–I from R–X with NaI in dry acetone Swarts: R–F with AgF or Hg2F2 Wurtz: R–R using Na in dry ether (symmetrical alkanes only) Sandmeyer: Ar–Cl/Br from diazonium salt with Cu2Cl2/Cu2Br2 and HX Grignard formation requires dry ether nucleophilic substitution is difficult because of partial double-bond character, but is enabled by o/p electron-withdrawing groups such as NO2, or by harsh conditions through a benzyne intermediate 2-Bromo-2-methylpropane with aqueous KOH reacts quickly by SN1: the tertiary carbocation is well stabilised, so the rate is first order and the product can be racemic if the carbon becomes chiral.
271 words, about 1 min09Alcohols, Phenols and Ethers
This domain tests acidity differences, distinguishing tests, dehydration and oxidation sequences, and named phenol reactions. Grignard addition: HCHO gives a primary alcohol, other aldehydes secondary, ketones tertiary dehydration order 3° 2° 1°, via carbocation stability oxidation: 1° alcohol → aldehyde → carboxylic acid; 2° → ketone; 3° resists oxidation Lucas test: 3° alcohol gives immediate turbidity, 2° after about five minutes, 1° no reaction at room temperature Victor Meyer test distinguishes 1°, 2° and 3° alcohols by colour acidic enough to react with NaOH but not with Na2CO3; Ka around 10⁻¹⁰ versus 10⁻¹⁶ for alcohols the phenoxide ion is resonance-stabilised electron-withdrawing groups raise acidity: p-nitrophenol o-nitrophenol m-nitrophenol phenol (ortho is weakened by intramolecular hydrogen bonding) Reimer–Tiemann gives salicylaldehyde; Kolbe gives salicylic acid; coupling with diazonium salts gives azo dyes Williamson synthesis works best with a primary halide; tertiary halides give elimination instead cleavage with HI: primary and secondary ethers react by SN2 giving iodomethane and an alcohol; aryl ethers give phenol and an alkyl iodide Zeisel method estimates methoxy groups To distinguish propan-1-ol, propan-2-ol and 2-methylpropan-2-ol, add Lucas reagent.
292 words, about 1 min10Aldehydes, Ketones and Carboxylic Acids
Expect nucleophilic addition reasoning, distinguishing tests, named reactions dependent on α-hydrogens, and acidity trends of substituted acids. nucleophilic addition order: HCHO RCHO R2CO (steric and electronic reasons) addition of HCN gives cyanohydrins; Grignard reagents give alcohols Tollens' reagent (ammoniacal AgNO3) oxidises aldehydes, giving a silver mirror; ketones do not react Fehling's solution gives a red Cu2O with aliphatic aldehydes, but aromatic aldehydes fail it iodoform test: CH3CO– or CH3CH(OH)– groups give yellow CHI3 aldol condensation needs dilute NaOH and an α-hydrogen Cannizzaro reaction needs concentrated NaOH and no α-hydrogen (HCHO, benzaldehyde) Clemmensen (Zn–Hg/HCl) and Wolff–Kishner (NH2NH2/KOH) both reduce C=O to CH2 HVZ reaction: carboxylic acids with Cl2/red P give α-halo acids acidity: Cl3CCOOH Cl2CHCOOH ClCH2COOH HCOOH CH3COOH, because –I groups stabilise the anion; alkyl groups are electron-releasing benzoic acid is stronger than acetic acid soda lime decarboxylation removes CO2 and gives one carbon fewer A compound gives a yellow precipitate with I2/NaOH and a silver mirror with Tollens' reagent.
274 words, about 1 min11Amines
Amines questions concentrate on basicity trends, preparative routes that control the degree of substitution, and diazonium chemistry. in the gas phase, more alkyl groups mean higher basicity (electron-releasing +I effect) in water, solvation and steric hindrance compete; for ethylamines the order is Et2NH EtNH2 Et3N NH3 aromatic amines are much weaker: the lone pair is delocalised into the ring; aniline is weaker than ammonia and methylamine electron-withdrawing groups reduce basicity: p-nitroaniline < aniline Hofmann bromamide: amide + Br2/KOH gives a primary amine with one carbon fewer Gabriel phthalimide synthesis gives pure primary amines but fails for aryl amines reduction of nitriles gives primary amines; reduction of amides or nitro compounds also works reductive amination of aldehydes/ketones gives 2° amines carbylamine test: primary amines with CHCl3/KOH give foul-smelling isocyanides Hinsberg test with benzenesulfonyl chloride separates 1°, 2° and 3° amines diazotisation: aniline with NaNO2 + HCl at 273–278 K coupling with phenol gives p-hydroxyazobenzene dye; Sandmeyer gives aryl halides Why is aniline a weaker base than ethylamine?
306 words, about 2 min12Biomolecules
Biomolecules questions check structures of sugars, the peptide and nucleic-acid backbone, and the vocabulary of denaturation, anomers and reducing sugars. glucose is an aldohexose; fructose is a ketohexose; both exist mainly as cyclic hemiacetals anomers differ only at the anomeric carbon (C1 of glucose, C2 of fructose) mutarotation is the change in specific rotation as α- and β-forms equilibrate in solution reducing sugars have a free anomeric hydroxyl: glucose, fructose, maltose, lactose sucrose is non-reducing because its glycosidic bond links C1 of glucose to C2 of fructose; hydrolysis gives glucose and fructose (invert sugar) amino acids are zwitterionic near neutral pH; the isoelectric point is the pH of zero net charge the peptide bond is an amide linkage formed by condensation; primary structure is the sequence, secondary structure includes α-helix and β-pleated sheet denaturation destroys secondary and tertiary structure but not the primary sequence enzymes are specific biocatalysts; a competitive inhibitor resembles the substrate DNA: deoxyribose, thymine, double helix with A–T and G–C base pairs RNA: ribose and uracil, usually single-stranded purines are adenine and guanine; pyrimidines are cytosine, thymine and uracil Sucrose does not reduce Tollens' or Fehling's reagent, yet after boiling with dilute acid the solution does.
327 words, about 2 min13Polymers and Chemistry in Everyday Life
This domain pairs polymer classification and named industrial polymers with the pharmacology vocabulary of everyday chemicals. addition polymers form by chain growth: polyethene, PVC, polystyrene, teflon condensation polymers form by step growth with loss of a small molecule: Nylon-6,6, PET, Bakelite homopolymer versus copolymer; elastomers versus fibres versus thermosetting plastics free-radical polymerisation: initiation, propagation, termination (benzoyl peroxide initiator) Ziegler–Natta catalysts give stereoregular polymers; Buna-S and Buna-N are copolymers natural rubber is cis-polyisoprene; vulcanisation with sulphur creates cross-links and raises strength starch, cellulose, proteins and nucleic acids are biopolymers biodegradable polymers include PHBV and Nylon-2-nylon-6 analgesics: aspirin, paracetamol; antibiotics: penicillin, chloramphenicol; antiseptics: dettol, bithional artificial sweeteners: saccharin, aspartame, sucralose soaps are sodium salts of fatty acids and precipitate scum in hard water; synthetic detergents avoid this Nylon-6,6 is made from adipic acid (hexanedioic acid) and hexamethylenediamine.
288 words, about 1 min