ICO Part B (ORI) cheat sheet

Chemical hazard classes: GHS pictograms (flame, skull, corrosion, health hazard, exclamation mark, gas cylinder, exploding bomb, flame over circle, environment).

Flash point: lowest temperature at which a liquid's vapour ignites momentarily; classifies flammable liquids (Category 1 <23°C, Category 2 23–60°C, Category 3 60–93°C).

Fume hood face velocity: typically 0.3–0.5 m/s (80–100 fpm); lower velocities risk escape, higher cause turbulence.

Cryogenic handling: use insulated gloves, face shield, and vented vessels; never seal liquid nitrogen containers (pressure build-up).

Peroxide formers: ethers (diethyl ether, THF, dioxane, isopropyl ether) form explosive peroxides; test with KI/starch or commercial strips before distillation; store over KOH or under argon.

Acid-base spill neutralisation: sodium bicarbonate for acids, dilute acetic acid or citric acid for bases; absorb with inert clay, never paper.

Compressed gas cylinders: secure upright with chain; oxidisers (O2) stored away from flammable gases; regulator not oil-contaminated.

Waste segregation: halogenated vs non-halogenated organic, aqueous heavy-metal, and oxidiser streams kept separate; never mix acids with organic waste.

Crystal field splitting (Δo) increases with ligand field strength: I⁻ < Br⁻ < Cl⁻ < F⁻ < OH⁻ < H2O < NH3 < en < NO2⁻ < CN⁻ ≈ CO.

High-spin vs low-spin: Δo > pairing energy gives low-spin; Δo < pairing energy gives high-spin; 3d metals often high-spin, 4d/5d usually low-spin.

Magnetic moment (spin-only) μ = √(n(n+2)) BM, where n = number of unpaired electrons; compare with measured μ to infer spin state.

Spectrochemical series and Jahn–Teller distortion: d9 (Cu2+) and high-spin d4 octahedral complexes show tetragonal elongation.

Synthesis of metal complexes: metal salt + ligand in suitable solvent; control pH, temperature, and stoichiometry; common methods include direct combination, ligand substitution, and template synthesis.

Characterisation: elemental analysis (C, H, N, metal by AAS/ICP), IR (metal–ligand stretches 400–600 cm⁻¹), UV-Vis (d-d transitions, charge transfer), molar conductance (1:1 electrolyte ~ 100–150 S cm² mol⁻¹ in water).

Coordination number and geometry: 2 linear, 3 trigonal planar, 4 tetrahedral/square planar, 5 trigonal bipyramidal/square pyramidal, 6 octahedral; 4-coordinate Ni2+ often tetrahedral, Pt2+ square planar.

Isomerism in coordination compounds: ionisation, hydrate, linkage, coordination, geometric (cis/trans), and optical isomerism; count using possible ligand arrangements.

Retrosynthetic analysis: break target into synthons; identify functional group interconversions; consider protecting groups (e.g., TBS for alcohols, Boc for amines).

Common C–C bond forming: Grignard addition to carbonyls, aldol condensation, Wittig, Suzuki coupling (Pd catalyst, base, aryl halide + boronic acid), Diels–Alder.

Oxidation: KMnO4 (strong), PCC (mild, primary alcohol → aldehyde), Swern; reduction: LiAlH4 (strong), NaBH4 (mild, aldehydes/ketones only), H2/Pd.

Thin-layer chromatography (TLC): Rf = distance travelled by spot / distance travelled by solvent front; visualise with UV, iodine, ninhydrin, or permanganate.

Column chromatography: stationary phase silica (normal phase) or C18 (reverse phase); eluotropic series: hexane < toluene < dichloromethane < ethyl acetate < acetone < methanol < water.

Recrystallisation: choose solvent where compound is soluble hot, insoluble cold; impurities soluble cold or insoluble hot; slow cooling yields larger crystals.

Melting point: sharp range indicates purity; mixed melting point depression identifies different compounds; eutectic behaviour.

IR and NMR identification: O–H broad 3200–3600 cm⁻¹; C=O 1700 cm⁻¹; 1H NMR chemical shifts: alkyl 0.9–1.5, allylic 1.6–2.0, OCH3 3.3–3.9, aromatic 6.5–8.0, aldehyde 9–10 ppm.

Titration formula: c_analyte × V_analyte × (stoichiometric ratio) = c_titrant × V_titrant; use mole ratio from balanced equation.

Primary standards: high purity, stable, non-hygroscopic, high molar mass (e.g., KHP for base, Na2CO3 for acid, K2Cr2O7 for redox, EDTA for complexometry).

Acid–base indicators: phenolphthalein (pH 8.2–10.0), methyl orange (3.1–4.4), bromothymol blue (6.0–7.6); choose indicator with pKa near equivalence pH.

Redox titration: KMnO4 (self-indicating, acidic medium), iodine/thiosulfate (starch indicator), dichromate (diphenylamine sulfonate).

Complexometric titration: EDTA forms 1:1 complexes with most metal ions; use buffer (pH 10 for Ca2+/Mg2+) and indicator (Eriochrome Black T, murexide).

Gravimetry: mass of analyte = mass of precipitate × (molar mass analyte / molar mass precipitate); examples: BaSO4 for sulfate, AgCl for chloride, Fe2O3 for iron.

Beer–Lambert law: A = εbc; absorbance A = log10(I0/I) = -log T; calibration curve linear at low concentration; deviations at high concentration or polychromatic light.

Spectrophotometric determination: choose λmax, prepare standards, blank with solvent; use quartz cells for UV (<340 nm), glass for visible.

Rate law: rate = k[A]^m[B]^n; order determined experimentally by initial rates or integrated rate laws (zero: [A] = [A]0 - kt; first: ln[A] = ln[A]0 - kt; second: 1/[A] = 1/[A]0 + kt).

Arrhenius equation: k = A exp(-Ea/RT); plot ln k vs 1/T gives slope -Ea/R.

Half-life: first-order t1/2 = ln2/k; second-order t1/2 = 1/(k[A]0); zero-order t1/2 = [A]0/(2k).

Thermodynamics: ΔG = ΔH - TΔS; ΔG° = -RT ln K; ΔG° = -nFE°cell; van't Hoff equation: ln(K2/K1) = -(ΔH°/R)(1/T2 - 1/T1).

Calorimetry: q = mcΔT; bomb calorimetry measures ΔU (constant volume); enthalpy ΔH = ΔU + ΔnRT.

Electrochemistry: Nernst equation E = E° - (RT/nF) ln Q; at 298 K, E = E° - (0.0592/n) log Q; cell potential E_cell = E_cathode - E_anode.

Conductivity: molar conductivity Λm = κ/c; Kohlrausch law: Λm = Λ°m - K√c for strong electrolytes; weak electrolytes have low Λm and increase sharply on dilution.

Kinetic measurement: initial rate method (vary one concentration at a time); isolation method (large excess of other reactants); stopped-flow for fast reactions.

Types of error: systematic (determinate, affects accuracy), random (indeterminate, affects precision), gross (blunders).

Accuracy vs precision: accuracy = closeness to true value; precision = reproducibility; measured by standard deviation (precision) and bias (accuracy).

Mean: x̄ = Σxi/n; standard deviation: s = √[Σ(xi - x̄)²/(n-1)]; relative standard deviation (RSD) = (s/x̄) × 100%.

Confidence interval: x̄ ± t(s/√n), where t depends on degrees of freedom (n-1) and confidence level (e.g., 95%).

Propagation of uncertainty: for addition/subtraction, absolute uncertainties add in quadrature: σ² = σa² + σb²; for multiplication/division, relative uncertainties add in quadrature.

Significant figures: addition/subtraction keep least decimal places; multiplication/division keep least significant figures; logarithms keep as many decimal places as significant figures in the number.

Linear regression: y = mx + c; slope m = Σ[(xi - x̄)(yi - ȳ)]/Σ(xi - x̄)²; intercept c = ȳ - m x̄; correlation coefficient r.

Rejection of outliers: Q-test (Q = |suspect - nearest|/range) compare with critical Q at 90% or 95%; Grubbs test for single outlier.

Degrees of unsaturation (double bond equivalent): DBE = C - H/2 + N/2 + 1 (halogens count as H); each DBE corresponds to a ring or π bond.

IR key stretches: O–H 3200–3600 (broad), N–H 3300–3500, C–H sp3 2850–2960, C≡C 2100–2260, C=O 1650–1750, C=C 1600–1680, aromatic 1450–1600.

1H NMR: integration gives number of protons; multiplicity from n+1 rule (first-order); coupling constants (J) in Hz; aromatic protons 6.5–8.5 ppm, aldehydic 9–10 ppm, carboxylic acid 10–12 ppm.

13C NMR: number of signals = number of non-equivalent carbons; chemical shift ranges: alkyl 0–50, C–O 50–90, aromatic 110–160, carbonyl 160–220 ppm.

Mass spectrometry: molecular ion (M+) gives molecular mass; isotope patterns (M+2 for Cl, Br); fragmentation gives structural clues (e.g., loss of 15 for CH3).

Combining data: determine molecular formula from MS and elemental analysis; calculate DBE; identify functional groups from IR; assemble fragments from NMR; confirm with 2D NMR (COSY, HSQC, HMBC) if available.

UV-Vis: conjugated systems absorb in UV (200–400 nm); λmax increases with conjugation (bathochromic shift); Beer-Lambert for quantitative analysis.

Elemental analysis: %C, %H, %N gives empirical formula; combine with molecular mass from MS to get molecular formula.