CBSE · Class 12

Chemistry Formulas for Class 12

Q: How many chapters are there in CBSE Class 12 Chemistry?

CBSE Class 12 Chemistry (2026-27) has 16 chapters covering Physical, Inorganic and Organic Chemistry. The key chapters for exam are Solutions, Electrochemistry, Chemical Kinetics, d-and-f Block Elements, Coordination Compounds, Haloalkanes, Alcohols, Aldehydes/Ketones, Amines and Biomolecules.

Q: Which chapter has the most formulas in Class 12 Chemistry?

Electrochemistry and Solutions are formula-heavy chapters with 10+ formulas each. Chemical Kinetics is also important with the Arrhenius equation and integrated rate laws. Focus on these three chapters first.

Q: Is the Nernst equation important for CBSE boards?

Yes, the Nernst equation is a 3-5 mark numerical in every CBSE Class 12 Chemistry board exam. You must know E_cell = E°_cell − (0.0592/n) log Q at 298 K and be able to calculate E_cell given concentrations.

Q: What is the van't Hoff factor and when is it used?

The van't Hoff factor (i) accounts for electrolyte dissociation or association in colligative property calculations. For electrolytes like NaCl (i ≈ 2), you multiply the colligative property formula by i. For associated solutes like acetic acid in benzene, i < 1.

Q: How do you calculate magnetic moment in Chemistry?

Use μ = √(n(n+2)) Bohr Magnetons, where n is the number of unpaired electrons. First write the electronic configuration of the ion (e.g. Fe³⁺ = [Ar] 3d⁵, n = 5), then plug in. μ = √(5×7) = 5.92 BM for Fe³⁺.

All important formulas chapter-wise for CBSE Class 12 Chemistry 2026-27 — quick-revision tables covering Physical, Inorganic and Organic Chemistry.

12 chapters50+ formulasCBSE 2026–27

Ch 1 Ch 2 Ch 3 Ch 4 Ch 5 Ch 6 Ch 7 Ch 8 Ch 9 Ch 10 Ch 11 Ch 12

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For reference only. Always verify formulas and information against your official NCERT textbooks or board-prescribed materials before use in exams. Learnizo does not guarantee absolute accuracy.

Ch 1.Solutions

Formula / Relation	Expression	Note
Mole Fraction of Solute	χ₂ = n₂ / (n₁ + n₂)	n₁ = moles of solvent, n₂ = moles of solute
Mass Percentage	w/w % = (mass of solute / mass of solution) × 100
Molarity (M)	M = moles of solute / volume of solution (L)	Unit: mol L⁻¹
Molality (m)	m = moles of solute / mass of solvent (kg)	Unit: mol kg⁻¹
Henry's Law	p = K_H · χ	p = partial pressure, χ = mole fraction of gas, K_H = Henry's constant
Raoult's Law (ideal solution)	p_A = p°_A · χ_A	p°_A = vapour pressure of pure A
Relative Lowering of Vapour Pressure	(p°_A − p_A) / p°_A = χ_B	χ_B = mole fraction of solute
Elevation of Boiling Point	ΔT_b = K_b · m	K_b = ebullioscopic constant
Depression of Freezing Point	ΔT_f = K_f · m	K_f = cryoscopic constant
Osmotic Pressure	π = CRT = (n/V)RT	R = 0.0821 L·atm·mol⁻¹·K⁻¹
van't Hoff Factor (i)	i = observed colligative property / normal colligative property	i > 1 for dissociation, i < 1 for association
Molar Mass from ΔT_b	M₂ = (1000 × K_b × w₂) / (ΔT_b × w₁)	w₁ = mass of solvent in g, w₂ = mass of solute in g
Molar Mass from ΔT_f	M₂ = (1000 × K_f × w₂) / (ΔT_f × w₁)

Ch 2.Electrochemistry

Formula / Relation	Expression	Note
Nernst Equation	E_cell = E°_cell − (RT/nF) ln Q	At 298 K: E_cell = E°_cell − (0.0592/n) log Q
Standard Cell Potential	E°_cell = E°_cathode − E°_anode
Gibbs Energy Change	ΔG° = −nFE°_cell	F = 96485 C mol⁻¹
Equilibrium Constant	log K = nE°_cell / 0.0592	At 298 K
Faraday's First Law	m = ZIt = (M/nF) · I · t	Z = electrochemical equivalent
Faraday's Second Law	m₁/m₂ = E₁/E₂	E = equivalent weight
Conductance (G)	G = 1/R = κ · A / l	κ = conductivity, A = area, l = length
Molar Conductivity (Λ_m)	Λ_m = κ × 1000 / M	M = molarity
Kohlrausch's Law	Λ°_m = ν₊λ°₊ + ν₋λ°₋	For weak electrolytes at infinite dilution
Degree of Dissociation (α)	α = Λ_m / Λ°_m

Ch 3.Chemical Kinetics

Formula / Relation	Expression	Note
Rate of Reaction	r = −(1/a)(d[A]/dt) = (1/b)(d[B]/dt)	aA + bB → products
First-Order Rate Law	r = k[A]	k = rate constant
First-Order Integrated Rate Law	ln[A]_t = ln[A]₀ − kt	or [A]_t = [A]₀ · e^(−kt)
Half-Life (1st order)	t₁/₂ = 0.693 / k	Independent of initial concentration
Second-Order Half-Life	t₁/₂ = 1 / (k[A]₀)
Arrhenius Equation	k = A · e^(−Ea/RT)	A = frequency factor, Ea = activation energy
Arrhenius (log form)	log(k₂/k₁) = (Ea/2.303R)(1/T₁ − 1/T₂)	R = 8.314 J mol⁻¹ K⁻¹
Zero-Order Integrated Rate Law	[A]_t = [A]₀ − kt
Zero-Order Half-Life	t₁/₂ = [A]₀ / 2k

Ch 4.d- and f-Block Elements

Formula / Relation	Expression	Note
Magnetic Moment (spin-only)	μ = √(n(n+2)) BM	n = number of unpaired electrons, BM = Bohr Magneton
Number of Unpaired Electrons	n from electronic configuration of ion	e.g. Fe²⁺ = [Ar] 3d⁶ → 4 unpaired

Ch 5.Coordination Compounds

Formula / Relation	Expression	Note
EAN Rule	EAN = Z − Ox.State + 2 × (# ligands × e⁻ donated)	Effective Atomic Number
Crystal Field Splitting (oct.)	Δ_o = 10Dq	e_g orbitals raised by 6Dq; t₂g lowered by 4Dq
CFSE (t₂g^a e_g^b, octahedral)	CFSE = (−4a + 6b) × Dq

Ch 6.Haloalkanes and Haloarenes

Formula / Relation	Expression	Note
SN2 Rate	r = k[R–X][Nu⁻]	Bimolecular, backside attack, inversion of configuration
SN1 Rate	r = k[R–X]	Unimolecular, carbocation intermediate, racemisation

Ch 7.Alcohols, Phenols and Ethers

Formula / Relation	Expression	Note
Lucas Test (order)	3° > 2° > 1° alcohol with ZnCl₂/conc. HCl	3° reacts immediately, 1° requires heating
Williamson Synthesis	R–O⁻ + R'–X → R–O–R' + X⁻	Best for unsymmetrical ethers

Ch 8.Aldehydes, Ketones and Carboxylic Acids

Formula / Relation	Expression	Note
Cannizzaro Ratio	50% alcohol + 50% acid	Disproportionation of HCHO or PhCHO with NaOH
Iodoform Test	CH₃COR + I₂/NaOH → CHI₃ (yellow ppt)	Also positive for CH₃OH, C₂H₅OH, CH₃CHOH-R

Ch 9.Amines

Formula / Relation	Expression	Note
Basicity Order	Aliphatic amines > NH₃ > Aromatic amines	Due to electron donation by alkyl vs. withdrawal by aromatic ring
Carbylamine Reaction	R–NH₂ + CHCl₃ + KOH → R–NC (foul smell)	Test for 1° amines only

Ch 10.Biomolecules

Formula / Relation	Expression	Note
Degree of Unsaturation (DBE)	DBE = (2C + 2 + N − H − X) / 2	C, H, N, X from molecular formula
Peptide Bond	–CO–NH– (amide linkage between amino acids)

Ch 11.Polymers

Formula / Relation	Expression	Note
Degree of Polymerisation (DP)	DP = Molar mass of polymer / Molar mass of monomer

Ch 12.Surface Chemistry

Formula / Relation	Expression	Note
Freundlich Adsorption Isotherm	x/m = k · p^(1/n)	x = mass adsorbed, m = mass of adsorbent; 1/n < 1
Langmuir Adsorption Isotherm	p/(x/m) = 1/(ab) + p/a	Monolayer, linear plot of p/(x/m) vs p

Frequently Asked Questions

How many chapters are there in CBSE Class 12 Chemistry?

CBSE Class 12 Chemistry (2026-27) has 16 chapters covering Physical, Inorganic and Organic Chemistry. The key chapters for exam are Solutions, Electrochemistry, Chemical Kinetics, d-and-f Block Elements, Coordination Compounds, Haloalkanes, Alcohols, Aldehydes/Ketones, Amines and Biomolecules.

Which chapter has the most formulas in Class 12 Chemistry?

Electrochemistry and Solutions are formula-heavy chapters with 10+ formulas each. Chemical Kinetics is also important with the Arrhenius equation and integrated rate laws. Focus on these three chapters first.

Is the Nernst equation important for CBSE boards?

Yes, the Nernst equation is a 3-5 mark numerical in every CBSE Class 12 Chemistry board exam. You must know E_cell = E°_cell − (0.0592/n) log Q at 298 K and be able to calculate E_cell given concentrations.

What is the van't Hoff factor and when is it used?

The van't Hoff factor (i) accounts for electrolyte dissociation or association in colligative property calculations. For electrolytes like NaCl (i ≈ 2), you multiply the colligative property formula by i. For associated solutes like acetic acid in benzene, i < 1.

How do you calculate magnetic moment in Chemistry?

Use μ = √(n(n+2)) Bohr Magnetons, where n is the number of unpaired electrons. First write the electronic configuration of the ion (e.g. Fe³⁺ = [Ar] 3d⁵, n = 5), then plug in. μ = √(5×7) = 5.92 BM for Fe³⁺.

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