CBSE Class 12 Chemistry All Formulas and Reactions List 2027

In short: This is the complete reference list of all formulas, named reactions, and key equations for CBSE Class 12 Chemistry 2027. Physical Chemistry has about 25 key formulas. Organic Chemistry has 20+ named reactions. Inorganic Chemistry has important compound preparations and properties. Bookmark this page for daily revision in the last month before your board exam.

How to Use This List

Physical Chemistry formulas: Memorize and practice in numerical problems. These carry 15-20 marks.
Organic named reactions: Write each reaction with reagents and conditions. These are tested in every paper.
Inorganic Chemistry: Focus on preparation methods, properties, and trends.
Revise daily: Spend 20 minutes each day going through one section.

Physical Chemistry Formulas

Solutions (Chapter 2)

Raoult's Law: p = p°₁x₁ + p°₂x₂

For a solution of non-volatile solute: p = p°₁x₁ (where x₁ = mole fraction of solvent)

Relative lowering of vapour pressure: (p° - p)/p° = x₂ = n₂/(n₁ + n₂)

Elevation in boiling point: ΔTb = Kb × m

Where: Kb = molal elevation constant, m = molality

Depression in freezing point: ΔTf = Kf × m

Osmotic pressure: π = CRT = (n/V)RT

Where: C = molar concentration, R = gas constant, T = temperature in K

Van't Hoff factor: i = observed colligative property / calculated colligative property i = 1 + (n-1)α (for dissociation) i = 1 - (1 - 1/n)α (for association)

Mole fraction: x₁ = n₁/(n₁ + n₂) Molality: m = moles of solute / kg of solvent Molarity: M = moles of solute / litres of solution

Electrochemistry (Chapter 3)

Nernst Equation: E_cell = E°_cell - (RT/nF) ln Q E_cell = E°_cell - (0.0591/n) log Q (at 298 K)

Standard cell potential: E°_cell = E°_cathode - E°_anode

Relation between ΔG° and E°: ΔG° = -nFE°_cell

Conductance: G = 1/R = κ(A/l)

Where: κ = conductivity, A = area, l = distance

Molar conductivity: Λm = κ × 1000/M (if M is in mol/L)

Kohlrausch's Law: Λ°m(electrolyte) = Σλ°(cations) + Σλ°(anions)

Degree of dissociation: α = Λm / Λ°m

Faraday's Laws: m = ZIt = (M × I × t)/(n × F)

Where: F = 96485 C/mol, n = number of electrons

Chemical Kinetics (Chapter 4)

Rate of reaction: Rate = -d[R]/dt = d[P]/dt

Rate law: Rate = k[A]^x[B]^y

Integrated rate law (First order): k = (2.303/t) log([A]₀/[A])

Half-life (First order): t₁/₂ = 0.693/k

Integrated rate law (Zero order): [A] = [A]₀ - kt, t₁/₂ = [A]₀/2k

Arrhenius Equation: k = Ae^(-Ea/RT) log(k₂/k₁) = (Ea/2.303R)(1/T₁ - 1/T₂)

Solid State (Chapter 1)

Density of unit cell: d = (Z × M)/(a³ × Nₐ)

Where: Z = number of atoms per unit cell, a = edge length, Nₐ = Avogadro's number

Packing efficiency:

Simple cubic: 52.4%
BCC: 68%
FCC/CCP: 74%

Relationship between radius (r) and edge length (a):

Simple cubic: a = 2r
BCC: a = 4r/√3
FCC: a = 2√2 r

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Organic Chemistry: Named Reactions

Haloalkanes and Haloarenes (Chapter 10)

Wurtz Reaction: 2R-X + 2Na → (dry ether) → R-R + 2NaX

Finkelstein Reaction: R-Cl + NaI → (acetone) → R-I + NaCl

Swarts Reaction: R-Cl + AgF → R-F + AgCl

Fittig Reaction: 2C₆H₅Cl + 2Na → (dry ether) → C₆H₅-C₆H₅ + 2NaCl

Wurtz-Fittig Reaction: C₆H₅Cl + CH₃Cl + 2Na → (dry ether) → C₆H₅CH₃ + 2NaCl

Alcohols, Phenols, Ethers (Chapter 11)

Williamson Synthesis: R-ONa + R'-X → R-O-R' + NaX

Kolbe's Reaction (Phenol): C₆H₅ONa + CO₂ → (high P, T) → C₆H₄(OH)(COONa) → (acid) → Salicylic acid

Reimer-Tiemann Reaction: Phenol + CHCl₃ + NaOH → Salicylaldehyde (ortho-hydroxybenzaldehyde)

Aldehydes, Ketones, Carboxylic Acids (Chapter 12)

Aldol Condensation: 2CH₃CHO → (dilute NaOH) → CH₃CH(OH)CH₂CHO (aldol) On heating → CH₃CH=CHCHO + H₂O (crotonaldehyde)

Cannizzaro Reaction: 2HCHO + conc. NaOH → HCOONa + CH₃OH (disproportionation)

Clemmensen Reduction: R-CO-R' + Zn(Hg)/conc. HCl → R-CH₂-R'

Wolff-Kishner Reduction: R-CO-R' + NH₂NH₂ + KOH → (ethylene glycol, heat) → R-CH₂-R'

Tollens' Test (Silver Mirror Test): RCHO + 2[Ag(NH₃)₂]⁺ + 3OH⁻ → RCOO⁻ + 2Ag↓ + 4NH₃ + 2H₂O

Fehling's Test: RCHO + 2Cu²⁺ + 5OH⁻ → RCOO⁻ + Cu₂O↓(red) + 3H₂O

Hell-Volhard-Zelinsky (HVZ) Reaction: R-CH₂-COOH + Br₂ → (Red P) → R-CHBr-COOH + HBr (alpha halogenation)

Rosenmund Reduction: RCOCl + H₂ → (Pd-BaSO₄) → RCHO + HCl

Stephen Reduction: RCN + SnCl₂/HCl → RCH=NH → (hydrolysis) → RCHO

Etard Reaction: C₆H₅CH₃ + CrO₂Cl₂ → (CS₂) → C₆H₅CHO

Gattermann-Koch Reaction: C₆H₆ + CO + HCl → (AlCl₃) → C₆H₅CHO

Amines (Chapter 13)

Hofmann Bromamide Reaction: RCONH₂ + Br₂ + 4NaOH → RNH₂ + Na₂CO₃ + 2NaBr + 2H₂O

Gabriel Phthalimide Synthesis: Phthalimide + KOH → Potassium phthalimide + RX → N-alkyl phthalimide → (NaOH/H₂O) → Primary amine

Diazotisation: C₆H₅NH₂ + NaNO₂ + 2HCl → (0-5°C) → C₆H₅N₂⁺Cl⁻ + NaCl + 2H₂O

Sandmeyer Reaction: C₆H₅N₂⁺Cl⁻ + CuCl/HCl → C₆H₅Cl + N₂ C₆H₅N₂⁺Cl⁻ + CuBr/HBr → C₆H₅Br + N₂ C₆H₅N₂⁺Cl⁻ + CuCN/KCN → C₆H₅CN + N₂

Coupling Reaction: C₆H₅N₂⁺Cl⁻ + C₆H₅OH → (alkaline) → p-hydroxyazobenzene (orange dye)

Carbylamine Reaction (Isocyanide test): R-NH₂ + CHCl₃ + 3KOH → R-NC + 3KCl + 3H₂O (foul smell = primary amine)

Inorganic Chemistry: Key Reactions and Compounds

p-Block Elements (Chapter 7)

Preparation of ammonia: 2NH₄Cl + Ca(OH)₂ → CaCl₂ + 2NH₃ + 2H₂O

Ostwald Process (HNO₃): 4NH₃ + 5O₂ → (Pt catalyst, 500°C) → 4NO + 6H₂O 2NO + O₂ → 2NO₂ 3NO₂ + H₂O → 2HNO₃ + NO

Contact Process (H₂SO₄): S + O₂ → SO₂ 2SO₂ + O₂ → (V₂O₅) → 2SO₃ SO₃ + H₂SO₄ → H₂S₂O₇ (oleum) H₂S₂O₇ + H₂O → 2H₂SO₄

Preparation of ozone: 3O₂ → (UV/electrical discharge) → 2O₃

Coordination Compounds (Chapter 9)

IUPAC Naming Rules:

Cation first, then anion.
Ligands in alphabetical order.
Anionic ligands end in -o (chlorido, hydroxido, cyanido).
Neutral ligands: aqua (H₂O), ammine (NH₃), carbonyl (CO).
Metal oxidation state in Roman numerals in parentheses.

d-Block Elements (Chapter 8)

Preparation of KMnO₄: 2MnO₂ + 4KOH + O₂ → 2K₂MnO₄ + 2H₂O 3K₂MnO₄ + 2CO₂ → 2KMnO₄ + MnO₂ + 2K₂CO₃

Preparation of K₂Cr₂O₇: 4FeCr₂O₄ + 8Na₂CO₃ + 7O₂ → 8Na₂CrO₄ + 2Fe₂O₃ + 8CO₂ 2Na₂CrO₄ + H₂SO₄ → Na₂Cr₂O₇ + Na₂SO₄ + H₂O

Quick Revision Checklist

Must-know for the exam:

For chapter-wise marks distribution, see our CBSE Class 12 Chemistry marks weightage guide. For Physics, see the CBSE Class 12 Physics derivations list.

Frequently Asked Questions

How many named reactions are there in CBSE Class 12 Chemistry?

There are approximately 20-25 named reactions across Organic Chemistry chapters. The most frequently tested are: Aldol condensation, Cannizzaro, Clemmensen, Wolff-Kishner, Sandmeyer, Hofmann bromamide, Williamson synthesis, Reimer-Tiemann, Kolbe, and HVZ reaction.

Which formulas are most important for numericals?

Nernst equation (Electrochemistry), colligative property formulas (Solutions), first-order kinetics equations, and Arrhenius equation are the most numerically tested. Practice at least 10 problems for each.

Should I memorize all the reactions or understand the mechanism?

Both. Memorize the reactants, reagents, conditions, and products for each named reaction. But also understand the mechanism (SN1, SN2, nucleophilic addition) because CBSE increasingly asks mechanism-based questions.

How do I remember so many reactions?

Group them by chapter and reaction type. Practice writing 5 reactions daily from different chapters. Use flashcards with the reaction name on one side and the complete reaction on the other. Within 2 weeks of daily practice, most reactions will be memorized.

Are preparation methods of compounds important?

Yes. Contact Process (H₂SO₄), Ostwald Process (HNO₃), Hall-Heroult (Al extraction), and KMnO₄/K₂Cr₂O₇ preparation are frequently tested for 3-5 marks.

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