Physical Chemistry Class 12 – Notes, Formulas & Short Revision Guide (2025)

Class 12 is one of the most crucial stages in a student’s academic life, and Chemistry plays a significant role in shaping overall performance, especially for students preparing for board exams as well as competitive exams like JEE, NEET, and other entrance tests.

Among the three branches of Chemistry — Physical Chemistry, Organic Chemistry, and Inorganic Chemistry — Physical Chemistry holds a very important place. It deals with the principles, laws, mathematical concepts, and quantitative aspects of chemical systems.

In this detailed blog, we will cover the complete Physical Chemistry Class 12 notes, including:

• Important chapters

• Key concepts and formulas

• Short notes for revision

• Tips to prepare for exams

This guide will help students quickly revise Physical Chemistry Class 12 before exams in a concise and easy-to-understand manner.

Physical Chemistry Class 12 – Notes, Formulas & Short Revision Guide (2025)

Chapters of Physical Chemistry Class 12

The Physical Chemistry part of Class 12 mainly covers the following chapters as per NCERT and most exam boards:

1. Solid State

2. Solutions

3. Electrochemistry

4. Chemical Kinetics

5. Surface Chemistry

Now, let’s go through each chapter one by one with short notes, important formulas, and key concepts.

1. Solid State

This chapter deals with the arrangement of particles in solids, types of solids, and unit cell calculations.

 Types of Solids

• Crystalline solids – Long-range order, sharp melting point, anisotropic.

• Amorphous solids – Irregular arrangement, no sharp melting point, isotropic.

 Types of Crystalline Solids

1. Ionic solids

2. Molecular solids

3. Covalent solids

4. Metallic solids

 Important Formulas

• Density of a unit cell:

  d=z×Ma3×NAd = \frac{z \times M}{a^3 \times N_A}d=a3×NA​z×M​

  where
  z = number of atoms per unit cell,
  M = molar mass,
  a = edge length of unit cell,
  N_A = Avogadro’s number.

• Packing efficiency:
  SC = 52.4%, BCC = 68%, FCC = 74%.

 Short Notes

• Edge length relation:
  SC → $a=2r$,
  BCC → a=4r3a = \frac{4r}{\sqrt{3}}a=3​4r​,
  FCC → a=22r1a = \frac{2\sqrt{2}r}{1}a=122​r​.

• Defects in solids: Schottky defect, Frenkel defect, Interstitial defect, Metal deficiency defect.

2. Solutions

This chapter focuses on types of solutions, concentration terms, colligative properties, and Raoult’s Law.

 Important Definitions

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

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

• Mole fraction (X): Moles of a component / Total moles.

 Colligative Properties

1. Relative Lowering of Vapor Pressure:

   p0−pp0=Xsolute\frac{p^0 – p}{p^0} = X_{solute}p0p0−p​=Xsolute​

2. Elevation of Boiling Point:

   ΔTb=Kb×m\Delta T_b = K_b \times mΔTb​=Kb​×m

3. Depression of Freezing Point:

   ΔTf=Kf×m\Delta T_f = K_f \times mΔTf​=Kf​×m

4. Osmotic Pressure:

   $$\pi =CRT$$

Short Notes

• Raoult’s Law: Partial vapor pressure of a component = Mole fraction × Pure vapor pressure.

• Abnormal molar mass correction is done using Van’t Hoff factor (i).

3. Electrochemistry

Electrochemistry studies the relationship between chemical energy and electrical energy.

Key Concepts

• Electrochemical cell – Converts chemical energy into electrical energy (Galvanic cell).

• Electrolysis – Conversion of electrical energy into chemical energy.

Important Formulas

1. Nernst Equation:

   Ecell=Ecell0−0.0591nlog⁡QE_{cell} = E^0_{cell} – \frac{0.0591}{n} \log QEcell​=Ecell0​−n0.0591​logQ

2. Relation between ∆G and EMF:

   ΔG=−nFEcell\Delta G = -nFE_{cell}ΔG=−nFEcell​

3. Kohlrausch’s Law:

   Λm0=Λm0(cation)+Λm0(anion)\Lambda_m^0 = \Lambda_m^0 (cation) + \Lambda_m^0 (anion)Λm0​=Λm0​(cation)+Λm0​(anion)

4. Conductance Relation:

   κ=1ρ,Λm=κ×1000C\kappa = \frac{1}{\rho}, \quad \Lambda_m = \frac{\kappa \times 1000}{C}κ=ρ1​,Λm​=Cκ×1000​

 Short Notes

• Standard electrode potential helps predict feasibility of redox reactions.

• Fuel cells and batteries (like Lead storage battery, Dry cell, Lithium-ion battery) are important applications.

4. Chemical Kinetics

This chapter deals with the speed of reactions and factors affecting them.

 Key Terms

• Rate of reaction: Change in concentration / Time.

• Order of reaction: Sum of powers of concentration terms in rate law.

• Molecularity: Number of reactant molecules in a single step.

 Important Formulas

1. Rate law equation:

   r=k[A]m[B]nr = k[A]^m [B]^nr=k[A]m[B]n

2. Integrated Rate Laws:

   • First order:

     k=2.303tlog⁡[R0][R]k = \frac{2.303}{t} \log \frac{[R_0]}{[R]}k=t2.303​log[R][R0​]​

   • Half-life:

     t1/2=0.693kt_{1/2} = \frac{0.693}{k}t1/2​=k0.693​

3. Arrhenius Equation:

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

 Short Notes

• Order of reaction may be fractional or zero.

• Factors affecting rate: concentration, temperature, catalyst, surface area, nature of reactants.

5. Surface Chemistry

This chapter deals with adsorption, catalysis, and colloids.

 Adsorption

• Adsorption isotherm (Freundlich):

  xm=kP1/n\frac{x}{m} = k P^{1/n}mx​=kP1/n

 Catalysis

• Homogeneous and heterogeneous catalysis.

• Enzyme catalysis → Highly specific & efficient.

 Colloids

• Types: Lyophilic & Lyophobic.

• Properties: Tyndall effect, Brownian motion, Electrophoresis.

• Preparation: Dispersion & Condensation methods.

 Short Notes

• Hardy–Schulze rule: Higher charge of coagulating ion = greater precipitation power.

• Protective colloids prevent coagulation (e.g., gelatin).

Quick Revision Notes for Physical Chemistry Class 12

Here’s a one-page summary for last-minute revision:

1. Solid State: Unit cell, packing efficiency, density formula, defects.

2. Solutions: Colligative properties formulas, Raoult’s law, Van’t Hoff factor.

3. Electrochemistry: Nernst equation, EMF relation, Kohlrausch’s law, batteries.

4. Chemical Kinetics: Rate law, first-order kinetics, Arrhenius equation.

5. Surface Chemistry: Adsorption isotherm, catalysis, colloid properties.

Preparation Tips for Physical Chemistry Class 12

1. Learn and revise all formulas regularly.

2. Solve NCERT examples and numerical problems.

3. Make a formula sheet for last-minute revision.

4. Practice previous year board exam questions.

5. Revise short notes daily for better retention.

 FAQs

Physical Chemistry Class 12

Q1. What are the main chapters of Physical Chemistry Class 12?

Answer: The main chapters of Physical Chemistry Class 12 are:

1. Solid State

2. Solutions

3. Electrochemistry

4. Chemical Kinetics

5. Surface Chemistry

Q2. How to prepare Physical Chemistry Class 12 for board exams?

Answer:

• Revise all important formulas regularly.

• Solve NCERT examples, exercise questions, and numerical problems.

• Make short notes and practice previous years’ question papers.

• Focus more on conceptual clarity rather than rote learning.

Q3. What is the difference between Molecularity and Order of Reaction?

Answer:

• Molecularity is the total number of molecules colliding in a single step of a reaction (always a whole number).

• Order of Reaction is the sum of the powers of concentration terms in the rate law (may be fractional, zero, or whole).

Q4. What is the formula for density of a unit cell in Solid State?

Answer:

d=z×Ma3×NAd = \frac{z \times M}{a^3 \times N_A}d=a3×NA​z×M​

where,

• $z$ = Number of atoms in unit cell

• $M$ = Molar mass

• $a$ = Edge length of unit cell

• NAN_ANA​ = Avogadro’s number

Q5. Which colligative property is used to calculate molar mass?

Answer: Colligative properties such as Elevation in Boiling Point (ΔT_b), Depression in Freezing Point (ΔT_f), and Osmotic Pressure (π) are used to determine the molar mass of a solute.

Q6. What is Nernst Equation in Electrochemistry?

Answer:
The Nernst Equation is:

Ecell=Ecell0−0.0591nlog⁡QE_{cell} = E^0_{cell} – \frac{0.0591}{n} \log QEcell​=Ecell0​−n0.0591​logQ

It helps in calculating the electrode potential under non-standard conditions.

Q7. Which is easier in Chemistry: Physical, Organic, or Inorganic?

Answer: It depends on individual interest. For many students, Physical Chemistry is considered easier because it is formula-based and numerical. Organic requires logical understanding of mechanisms, while Inorganic requires memorization.

Q8. What is the half-life formula for a first-order reaction?

Answer:

t1/2=0.693kt_{1/2} = \frac{0.693}{k}t1/2​=k0.693​

where $k$ is the rate constant.

Q9. What are examples of colloids from daily life?

Answer: Milk, Butter, Fog, Smoke, Foam, Shaving Cream, and Blood are common examples of colloids.

Q10. Is Physical Chemistry Class 12 important for JEE and NEET?

Answer: Yes, Physical Chemistry is very important for both JEE and NEET. Topics like Chemical Kinetics, Electrochemistry, Solutions, and Surface Chemistry carry significant weightage in competitive exams.

Conclusion

Physical Chemistry Class 12 is all about understanding concepts, applying formulas, and solving numerical problems. With proper practice and revision, this subject can become one of the highest scoring parts of Chemistry.

This complete revision guide of Physical Chemistry Class 12 with short notes and formulas will help you during your preparation and ensure that you are exam-ready.

Visit My Insta I’d 

Physics Formula