Chemistry is one of the most crucial subjects in CBSE Class 12 Science stream. It plays a major role in board exams, entrance tests like JEE, NEET, and also helps build the foundation for higher studies. However, Chemistry can feel vast and complex — with so many equations, reactions, and theories.
To help students revise easily, here are complete Class 12 Chemistry Notes (2025), covering every chapter, topic, formula, and example in a simplified way. These notes will make your last-minute preparation effective and ensure conceptual clarity.
CBSE Class 12 Chemistry Notes 2025 – Chapter-wise Revision, Formulas & Examples
Chapter 1: Solid State
Key Concepts
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Types of Solids:
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Crystalline Solids: Ordered arrangement (NaCl, Diamond)
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Amorphous Solids: Irregular arrangement (Glass, Plastic)
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Crystal Lattice and Unit Cell
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Types: Simple Cubic, Body-Centered Cubic (BCC), Face-Centered Cubic (FCC)
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Formula:
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Density = z×Ma3×NA\frac{z \times M}{a^3 \times N_A}
where z = number of atoms per unit cell, a = edge length
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Defects in Solids
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Point Defects: Vacancy, Interstitial, Frenkel, Schottky
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Example: NaCl shows Schottky defect due to equal cation and anion vacancies.
Chapter 2: Solutions
Types of Solutions
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Solid in liquid, gas in liquid, liquid in liquid, etc.
Concentration Units
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Molarity (M) = Moles of solute / Volume of solution (L)
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Molality (m) = Moles of solute / Mass of solvent (kg)
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Mole Fraction (χ) = Moles of component / Total moles
Colligative Properties
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Relative lowering of vapor pressure
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Elevation in boiling point:
ΔTb=Kb×m\Delta T_b = K_b \times m -
Depression in freezing point:
ΔTf=Kf×m\Delta T_f = K_f \times m -
Osmotic pressure:
π=CRT\pi = C R T
Example: Find boiling point elevation of 1m NaCl solution, given Kb=0.52K_b = 0.52.
ΔTb=0.52×2=1.04°C\Delta T_b = 0.52 \times 2 = 1.04°C (as NaCl dissociates into 2 ions).
Chapter 3: Electrochemistry
Key Terms
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Electrode Potential: Potential difference at electrode-solution interface.
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Cell: Device that converts chemical energy into electrical energy.
Nernst Equation
Ecell=E°cell−0.0591nlog[Products][Reactants]E_{cell} = E°_{cell} – \frac{0.0591}{n} \log \frac{[Products]}{[Reactants]}
Electrolytic and Galvanic Cells
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Galvanic Cell: Chemical → Electrical energy
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Electrolytic Cell: Electrical → Chemical energy
Faraday’s Laws
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First Law: Mass ∝ Charge passed
W=ZItW = ZIt -
Second Law: Masses of different substances deposited are proportional to equivalent weights.
Example: Calculate mass of Cu deposited when 2A current passes for 30 min.
W=ZIt=0.00033×2×1800=1.188gW = ZIt = 0.00033 × 2 × 1800 = 1.188g
Chapter 4: Chemical Kinetics
Rate of Reaction
Rate=−d[R]dt=d[P]dtRate = -\frac{d[R]}{dt} = \frac{d[P]}{dt}
Order and Molecularity
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Order → Sum of powers in rate law
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Molecularity → No. of molecules in rate-determining step
Integrated Rate Equations
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First Order:
k=2.303tlog[A]0[A]k = \frac{2.303}{t} \log \frac{[A]_0}{[A]}
Temperature Effect (Arrhenius Equation)
k=Ae−Ea/RTk = A e^{-E_a/RT}
Example: If rate doubles when T increases by 10°C, activation energy ≈ 50 kJ/mol.
Chapter 5: Surface Chemistry
Adsorption
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Physisorption → weak forces
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Chemisorption → strong chemical bonds
Catalysis
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Increases rate without being consumed
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Example: MnO₂ catalyzes decomposition of KClO₃.
Colloids
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Dispersed phase + Dispersion medium
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Types: Sol, Gel, Emulsion, Aerosol
Tyndall Effect: Scattering of light by colloidal particles.
Chapter 6: General Principles and Processes of Isolation of Elements
Steps in Metallurgy
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Concentration of ore
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Roasting/Calcination
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Reduction
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Refining
Examples
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Roasting: 2ZnS+3O2→2ZnO+2SO22ZnS + 3O_2 → 2ZnO + 2SO_2
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Electrolytic Refining of Cu: Impure Cu → Anode, Pure Cu → Cathode
Chapter 7: p-Block Elements
Group 15 (N, P, As, Sb, Bi)
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Important Compound: Ammonia (NH₃), Nitric Acid (HNO₃)
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NH3+O2→NO+H2ONH₃ + O_2 → NO + H_2O
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Oxidation States: -3 to +5
Group 16 (O, S, Se, Te)
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Example: 2H2S+SO2→3S+2H2O2H_2S + SO_2 → 3S + 2H_2O
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Sulphuric Acid: Strong dibasic acid.
Group 17 (Halogens)
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Reactivity: F₂ > Cl₂ > Br₂ > I₂
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Displacement reactions common.
Group 18 (Noble Gases)
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Mostly inert, but Xe forms compounds like XeF₂, XeF₄.
Chapter 8: d and f Block Elements
Transition Metals
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Variable oxidation states
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Colored ions (due to d–d transition)
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Catalytic properties
Lanthanides and Actinides
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Show +3 oxidation state mainly
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Actinides are radioactive
Example: Cr3+Cr^{3+} (green), MnO4−MnO_4^- (purple)
Chapter 9: Coordination Compounds
Key Terms
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Ligand: Atom or ion donating electron pairs
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Coordination Number: No. of ligand donor atoms attached to metal
Nomenclature Example
[Co(NH3)6]Cl3[Co(NH_3)_6]Cl_3 → Hexaamminecobalt(III) chloride
Isomerism
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Ionization, Geometrical, Optical
Bonding (Valence Bond Theory)
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[Fe(CN)6]4−[Fe(CN)_6]^{4-}: Low-spin, inner orbital complex
Chapter 10: Haloalkanes and Haloarenes
Preparation
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From alcohols:
ROH+HX→RX+H2OROH + HX → RX + H_2O
Reactions
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Substitution: R−X+OH−→R−OH+X−R-X + OH^- → R-OH + X^-
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Elimination: CH3CH2Br+KOH(alc.)→CH2=CH2+H2O+KBrCH_3CH_2Br + KOH(alc.) → CH_2=CH_2 + H_2O + KBr
Example: SN1 vs SN2 — SN1 is two-step, SN2 is one-step.
Chapter 11: Alcohols, Phenols, and Ethers
Preparation
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From Alkenes: Hydration
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From Grignard Reagents
Reactions
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Oxidation: CH3CH2OH→CH3CHO→CH3COOHCH_3CH_2OH → CH_3CHO → CH_3COOH
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Esterification: C2H5OH+CH3COOH→CH3COOC2H5+H2OC_2H_5OH + CH_3COOH → CH_3COOC_2H_5 + H_2O
Chapter 12: Aldehydes, Ketones, and Carboxylic Acids
Functional Group: –CHO, >C=O, –COOH
Reactions
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Nucleophilic Addition: HCN,NH2OH,NH2NH2HCN, NH_2OH, NH_2NH_2
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Oxidation: Aldehydes → Acids
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Reduction: Aldehydes → Alcohols
Example:
CH3CHO+HCN→CH3CH(OH)CNCH_3CHO + HCN → CH_3CH(OH)CN
Chapter 13: Amines
Classification:
Primary (1°), Secondary (2°), Tertiary (3°)
Preparation
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Reduction of nitro compounds
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Gabriel phthalimide synthesis
Reactions
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Hinsberg Test – distinguish 1°, 2°, 3° amines
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Diazotization: C6H5NH2+NaNO2+HCl→C6H5N2+Cl−C_6H_5NH_2 + NaNO_2 + HCl → C_6H_5N_2^+Cl^-
Chapter 14: Biomolecules
Carbohydrates
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Monosaccharides (Glucose), Disaccharides (Sucrose)
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Glucose Formula: C₆H₁₂O₆
Reaction: Glucose + Cu(OH)₂ → Blue solution
Proteins
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Made of amino acids linked by peptide bonds
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Denaturation destroys structure.
Nucleic Acids
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DNA, RNA made of nucleotides
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Base pairing: A–T, G–C
Chapter 15: Polymers
Types
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Addition Polymers: Polyethylene, PVC
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Condensation Polymers: Nylon-6,6; Bakelite
Example Reactions
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nCH2=CH2→(−CH2CH2−)nnCH_2=CH_2 → (-CH_2CH_2-)_n (Polyethylene)
Chapter 16: Chemistry in Everyday Life
Drugs
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Analgesics: Aspirin
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Antibiotics: Penicillin
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Antacids: Mg(OH)₂, Al(OH)₃
Cleansing Agents
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Soaps: Sodium salts of fatty acids
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Detergents: Sodium alkyl benzene sulfonate
Conclusion
CBSE Class 12 Chemistry is a balanced mix of theoretical and numerical concepts. Regular revision using these concise notes can save time and help in remembering every key formula and reaction. Focus on NCERT examples, important reactions, and numerical practice from Electrochemistry, Kinetics, and Solutions chapters. With clarity and consistency, scoring 90+ in Chemistry becomes achievable.
FAQs-CBSE Class 12 Chemistry Notes 2025
Q1. How many chapters are there in CBSE Class 12 Chemistry?
There are 16 chapters divided into Physical, Inorganic, and Organic Chemistry.
Q2. Which chapters are most important for board exams?
Electrochemistry, Chemical Kinetics, Coordination Compounds, and Aldehydes & Ketones are highly scoring.
Q3. What is the best way to revise Class 12 Chemistry?
Revise all formulas, reaction mechanisms, and NCERT examples regularly with short notes.
Q4. How to prepare Organic Chemistry for boards?
Focus on named reactions (Aldol, Cannizzaro, Sandmeyer, etc.) and practice mechanisms.
Q5. Are numerical problems asked in exams?
Yes, especially from Electrochemistry, Solutions, and Kinetics chapters.
Q6. What is the weightage of Physical Chemistry?
Around 30–35 marks in the CBSE board paper.
Q7. How to remember chemical equations easily?
Practice writing reactions repeatedly and understand reactant-product relationships.
Q8. Is NCERT enough for Class 12 Chemistry boards?
Yes, NCERT is the main book; just practice previous year papers for extra confidence.
Q9. Which is tougher – Organic or Physical Chemistry?
Students often find Organic tough, but with concept clarity, both can be mastered.
Q10. How can I score full marks in Chemistry practicals?
Follow procedures carefully, maintain neat records, and revise salt analysis & titration steps.