CBSE Class 12 Chemistry Notes 2025 – Chapter-wise Revision, Formulas & Examples

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

• Types of Solids:

  • Crystalline Solids: Ordered arrangement (NaCl, Diamond)

  • Amorphous Solids: Irregular arrangement (Glass, Plastic)

Crystal Lattice and Unit Cell

• Types: Simple Cubic, Body-Centered Cubic (BCC), Face-Centered Cubic (FCC)

• Formula:

  • Density = z×Ma3×NA\frac{z \times M}{a^3 \times N_A}a3×NA​z×M​
    where z = number of atoms per unit cell, a = edge length

Defects in Solids

• Point Defects: Vacancy, Interstitial, Frenkel, Schottky

• Example: NaCl shows Schottky defect due to equal cation and anion vacancies.

Chapter 2: Solutions

Types of Solutions

• Solid in liquid, gas in liquid, liquid in liquid, etc.

Concentration Units

• Molarity (M) = Moles of solute / Volume of solution (L)

• Molality (m) = Moles of solute / Mass of solvent (kg)

• Mole Fraction (χ) = Moles of component / Total moles

Colligative Properties

1. Relative lowering of vapor pressure

2. Elevation in boiling point:
   ΔTb=Kb×m\Delta T_b = K_b \times mΔTb​=Kb​×m

3. Depression in freezing point:
   ΔTf=Kf×m\Delta T_f = K_f \times mΔTf​=Kf​×m

4. Osmotic pressure:
   $\pi =CRT$

Example: Find boiling point elevation of 1m NaCl solution, given Kb=0.52K_b = 0.52Kb​=0.52.
ΔTb=0.52×2=1.04°C\Delta T_b = 0.52 \times 2 = 1.04°CΔTb​=0.52×2=1.04°C (as NaCl dissociates into 2 ions).

Chapter 3: Electrochemistry

Key Terms

• Electrode Potential: Potential difference at electrode-solution interface.

• 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]}Ecell​=E°cell​−n0.0591​log[Reactants][Products]​

Electrolytic and Galvanic Cells

• Galvanic Cell: Chemical → Electrical energy

• Electrolytic Cell: Electrical → Chemical energy

Faraday’s Laws

1. First Law: Mass ∝ Charge passed
   $W=ZIt$

2. 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.
$W=ZIt=0.00033\times 2\times 1800=1.188g$

Chapter 4: Chemical Kinetics

Rate of Reaction

Rate=−d[R]dt=d[P]dtRate = -\frac{d[R]}{dt} = \frac{d[P]}{dt}Rate=−dtd[R]​=dtd[P]​

Order and Molecularity

• Order → Sum of powers in rate law

• Molecularity → No. of molecules in rate-determining step

Integrated Rate Equations

• First Order:
  k=2.303tlog⁡[A]0[A]k = \frac{2.303}{t} \log \frac{[A]_0}{[A]}k=t2.303​log[A][A]0​​

Temperature Effect (Arrhenius Equation)

k=Ae−Ea/RTk = A e^{-E_a/RT}k=Ae−Ea​/RT

Example: If rate doubles when T increases by 10°C, activation energy ≈ 50 kJ/mol.

Chapter 5: Surface Chemistry

Adsorption

• Physisorption → weak forces

• Chemisorption → strong chemical bonds

Catalysis

• Increases rate without being consumed

• Example: MnO₂ catalyzes decomposition of KClO₃.

Colloids

• Dispersed phase + Dispersion medium

• 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

1. Concentration of ore

2. Roasting/Calcination

3. Reduction

4. Refining

Examples

• Roasting: 2ZnS+3O2→2ZnO+2SO22ZnS + 3O_2 → 2ZnO + 2SO_22ZnS+3O2​→2ZnO+2SO2​

• Electrolytic Refining of Cu: Impure Cu → Anode, Pure Cu → Cathode

Chapter 7: p-Block Elements

Group 15 (N, P, As, Sb, Bi)

• Important Compound: Ammonia (NH₃), Nitric Acid (HNO₃)

  • NH3+O2→NO+H2ONH₃ + O_2 → NO + H_2ONH3​+O2​→NO+H2​O

• Oxidation States: -3 to +5

Group 16 (O, S, Se, Te)

• Example: 2H2S+SO2→3S+2H2O2H_2S + SO_2 → 3S + 2H_2O2H2​S+SO2​→3S+2H2​O

• Sulphuric Acid: Strong dibasic acid.

Group 17 (Halogens)

• Reactivity: F₂ > Cl₂ > Br₂ > I₂

• Displacement reactions common.

Group 18 (Noble Gases)

• Mostly inert, but Xe forms compounds like XeF₂, XeF₄.

Chapter 8: d and f Block Elements

Transition Metals

• Variable oxidation states

• Colored ions (due to d–d transition)

• Catalytic properties

Lanthanides and Actinides

• Show +3 oxidation state mainly

• Actinides are radioactive

Example: Cr3+Cr^{3+}Cr3+ (green), MnO4−MnO_4^-MnO4−​ (purple)

Chapter 9: Coordination Compounds

Key Terms

• Ligand: Atom or ion donating electron pairs

• Coordination Number: No. of ligand donor atoms attached to metal

Nomenclature Example

[Co(NH3)6]Cl3[Co(NH_3)_6]Cl_3[Co(NH3​)6​]Cl3​ → Hexaamminecobalt(III) chloride

Isomerism

• Ionization, Geometrical, Optical

Bonding (Valence Bond Theory)

• [Fe(CN)6]4−[Fe(CN)_6]^{4-}[Fe(CN)6​]4−: Low-spin, inner orbital complex

Chapter 10: Haloalkanes and Haloarenes

Preparation

• From alcohols:
  ROH+HX→RX+H2OROH + HX → RX + H_2OROH+HX→RX+H2​O

Reactions

• Substitution: R−X+OH−→R−OH+X−R-X + OH^- → R-OH + X^-R−X+OH−→R−OH+X−

• Elimination: CH3CH2Br+KOH(alc.)→CH2=CH2+H2O+KBrCH_3CH_2Br + KOH(alc.) → CH_2=CH_2 + H_2O + KBrCH3​CH2​Br+KOH(alc.)→CH2​=CH2​+H2​O+KBr

Example: SN1 vs SN2 — SN1 is two-step, SN2 is one-step.

Chapter 11: Alcohols, Phenols, and Ethers

Preparation

• From Alkenes: Hydration

• From Grignard Reagents

Reactions

• Oxidation: CH3CH2OH→CH3CHO→CH3COOHCH_3CH_2OH → CH_3CHO → CH_3COOHCH3​CH2​OH→CH3​CHO→CH3​COOH

• Esterification: C2H5OH+CH3COOH→CH3COOC2H5+H2OC_2H_5OH + CH_3COOH → CH_3COOC_2H_5 + H_2OC2​H5​OH+CH3​COOH→CH3​COOC2​H5​+H2​O

Chapter 12: Aldehydes, Ketones, and Carboxylic Acids

Functional Group: –CHO, >C=O, –COOH

Reactions

• Nucleophilic Addition: HCN,NH2OH,NH2NH2HCN, NH_2OH, NH_2NH_2HCN,NH2​OH,NH2​NH2​

• Oxidation: Aldehydes → Acids

• Reduction: Aldehydes → Alcohols

Example:
CH3CHO+HCN→CH3CH(OH)CNCH_3CHO + HCN → CH_3CH(OH)CNCH3​CHO+HCN→CH3​CH(OH)CN

Chapter 13: Amines

Classification:

Primary (1°), Secondary (2°), Tertiary (3°)

Preparation

• Reduction of nitro compounds

• Gabriel phthalimide synthesis

Reactions

• Hinsberg Test – distinguish 1°, 2°, 3° amines

• Diazotization: C6H5NH2+NaNO2+HCl→C6H5N2+Cl−C_6H_5NH_2 + NaNO_2 + HCl → C_6H_5N_2^+Cl^-C6​H5​NH2​+NaNO2​+HCl→C6​H5​N2+​Cl−

Chapter 14: Biomolecules

Carbohydrates

• Monosaccharides (Glucose), Disaccharides (Sucrose)

• Glucose Formula: C₆H₁₂O₆
  Reaction: Glucose + Cu(OH)₂ → Blue solution

Proteins

• Made of amino acids linked by peptide bonds

• Denaturation destroys structure.

Nucleic Acids

• DNA, RNA made of nucleotides

• Base pairing: A–T, G–C

Chapter 15: Polymers

Types

1. Addition Polymers: Polyethylene, PVC

2. Condensation Polymers: Nylon-6,6; Bakelite

Example Reactions

• nCH2=CH2→(−CH2CH2−)nnCH_2=CH_2 → (-CH_2CH_2-)_nnCH2​=CH2​→(−CH2​CH2​−)n​ (Polyethylene)

Chapter 16: Chemistry in Everyday Life

Drugs

• Analgesics: Aspirin

• Antibiotics: Penicillin

• Antacids: Mg(OH)₂, Al(OH)₃

Cleansing Agents

• Soaps: Sodium salts of fatty acids

• 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.

CBSE Class 12 Chemistry Notes 2025

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