Revision Essentials

Curated 1-mark & 2-mark definitions based on 10-year CBSE analysis. 🎯

65+ Core Definitions
Top 5 Exam Predictions
πŸ”₯ 2026 Exam Predictions

Focus 200% on these: Kohlrausch's Law, Lanthanoid Contraction, Zwitterion structure, Pseudo 1st Order, and Ideal vs Non-Ideal deviations.

πŸ’‘ Exam Hack: The "Exact Word" Policy

CBSE examiners look for specific keywords like "infinite dilution", "per unit volume", or "non-volatile". Using these ensures a full 1 mark even if the grammar is slightly off!

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Solutions Definitions

Molarity (M) V. Imp

Number of moles of solute dissolved in one litre (1L) of solution.

Temp. Dependent M = n/V
Molality (m)

Number of moles of solute dissolved in one kilogram (1kg) of solvent.

Temp. Independent m = n/W(kg)
Raoult's Law Must Know

For a solution of volatile liquids, the partial vapour pressure of each component is directly proportional to its mole fraction.

Mathematical P = PΒ°x
Ideal Solution

A solution that obeys Raoult's law over the entire range of concentrations and shows no change in enthalpy or volume on mixing (\(\Delta H_{\text{mix}} = 0\)).

Azeotropes

Binary mixtures having the same composition in liquid and vapour phase and boil at a constant temperature.

Colligative Properties

Properties that depend only on the number of solute particles and not on their nature.

Electrochemistry Definitions

Molar Conductivity (\(\Lambda_m\))

Conductivity of all the ions produced by dissolving one mole of an electrolyte in a solution.

Kohlrausch's Law Repeated

At infinite dilution, molar conductivity of an electrolyte can be represented as the sum of individual contributions of the anion and cation.

Standard Hydrogen Electrode

A reference electrode used to measure standard electrode potentials, assigned a potential of exactly 0.00 V at all temperatures.

Fuel Cells

Galvanic cells that are designed to convert the energy of combustion of fuels directly into electrical energy.

Corrosion

Slow coating of the surfaces of metallic objects with oxides or other salts of the metal due to interaction with enviornment.

Chemical Kinetics

Order of Reaction

Sum of powers of the concentration of the reactants in the rate law expression.

Made for Ishu ❀️

Molecularity

Number of reacting species taking part in an elementary reaction, which must collide simultaneously.

Rate Constant (k)

Rate of reaction when the concentration of each reactant is unity (1 M).

Activation Energy (\(E_a\))

Minimum extra energy required by a reactant molecule to form an intermediate (activated complex).

Pseudo First Order

Reactions which are not truly of first order but under certain conditions behave as first order (e.g., Inversion of cane sugar).

Surface Chemistry (Definitions Goldmine)

Adsorption Basic

Accumulation of molecular species at the surface rather than in the bulk of a solid or liquid.

Tyndall Effect

Scattering of a beam of light by colloidal particles when passed through a colloidal solution.

Peptization

Process of converting a fresh precipitate into colloidal sol by shaking it with dispersion medium in presence of electrolyte.

Hardy-Schulze Rule Exam Choice

Greater the valence of the flocculating ion added, the greater is its power to cause precipitation.

d & f Block Elements

Lanthanoid Contraction V. Imp

Steady decrease in atomic and ionic radii of lanthanoid elements with increasing atomic number due to poor shielding of 4f electrons.

Transition Elements

Elements which have incompletely filled d-orbitals in its ground state or in any of its oxidation states.

Mischmetall

An alloy which consists of a lanthanoid metal (~ 95%) and iron (~ 5%) and traces of S, C, Ca and Al.

Coordination Compounds

Coordination Sphere

The central metal atom and the ligands that are directly attached to it, enclosed in square brackets.

Ambidentate Ligand

A ligand which can ligate through two different atoms (e.g. \(NO_2^-\) - it can bind through N or O).

Chelate Effect

When a di- or polydentate ligand binds to a metal ion, it forms a ring-like structure; this complex is more stable than others.

Haloalkanes & Haloarenes

Ambident Nucleophiles

Nucleophiles that possess two nucleophilic centers and can attack from either side (e.g. \(CN^-\), \(NO_2^-\)).

Chirality

Property of non-superimposability of an object on its mirror image.

Enantiomers

Stereoisomers related to each other as non-superimposable mirror images.

Alcohols, Phenols & Ethers

Denaturation of Alcohol

Process of making ethyl alcohol unfit for drinking by adding small amounts of poisonous substances like methanol or copper sulphate.

Reimer-Tiemann Reaction

Treatment of phenol with chloroform in the presence of sodium hydroxide to introduce an aldehyde group at the ortho position.

Aldehydes & Ketones

Aldol Condensation

Self-addition of aldehydes or ketones having \(\alpha\)-hydrogen in the presence of dilute alkali to form \(\beta\)-hydroxy carbonyls.

Cannizzaro Reaction

Redox reaction of aldehydes which lack \(\alpha\)-hydrogen on treatment with concentrated alkali.

Carboxylic Acids

Hell-Volhard-Zelinsky (HVZ)

Reaction of carboxylic acids having \(\alpha\)-hydrogen with \(Cl_2\) or \(Br_2\) in presence of red phosphorus to form \(\alpha\)-halo acids.

Decarboxylation

Elimination of a molecule of carbon dioxide from a carboxylic acid to form a hydrocarbon.

Amines

Gabriel Phthalimide Synthesis

A method for the preparation of primary aliphatic amines by the reaction of phthalimide with alkyl halides followed by hydrolysis.

Hinsberg Reagent

Benzenesulphonyl chloride, used for distinguishing between \(1^\circ\), \(2^\circ\) and \(3^\circ\) amines.

Hofmann Bromamide Degradation

Treatment of an amide with bromine and aqueous NaOH to form a primary amine with one carbon atom less.

Biomolecules (Mark Scoring)

Zwitterion Repeated

A dipolar ion formed when the carboxylic group loses a proton and amino group accepts it from within the molecule.

Peptide Linkage

The \(β€”CONHβ€”\) bond formed between two amino acid units through elimination of a water molecule.

Anomers

Cyclic monosaccharides that differ in configuration only at the hemiacetal or hemiketal carbon (C-1).

Denaturation of Protein

Loss of biological activity of protein due to disruption of secondary and tertiary structures by physical or chemical change.

Chemical Distinction Tests (3 Mark Guaranteed)

Lucas Test

Distinguishes 1Β°, 2Β°, 3Β° Alcohols. 3Β° alcohols give turbidity immediately, 2Β° in 5 mins, 1Β° only on heating.

Tollens' & Fehling's Test

Distinguishes Aldehydes from Ketones. Aldehydes give **Silver Mirror** with Tollens' and **Red ppt** with Fehling's (except Benzaldehyde).

Iodoform Test V. Imp

Identifies **Methyl Ketones** (\(CH_3CO-\)) and ethanol/2-propanol. Gives **Yellow ppt** (\(CHI_3\)).

Carbylamine Test

Only for **Primary Amines** (Aliphatic/Aromatic). Gives **foul-smelling** isocyanides.

Organic Conversion Hacks

Step-Up (Increase Carbon)

Use \(KCN\) followed by hydrolysis (\(\to\) acid) or reduction (\(\to\) amine). Wurtz reaction is also an option for alkanes.

Step-Down (Decrease Carbon)

Use **Hofmann Bromamide Degradation** (Amide \(\to\) Amine) or **Decarboxylation** (Acid \(\to\) Alkane).

The Diazonium Highway

Convert everything to **Benzene Diazonium Chloride** (\(C_6H_5N_2^+Cl^-\)) to reach phenol, haloarenes, or benzonitrile easily.