Physics Kinetic Theory of Gases Syllabus for NEET 2026

The Kinetic Theory of Gases explains the behaviour of gases by studying the motion of microscopic particles present inside them. It connects observable properties such as pressure, temperature, and volume with the continuous random movement and collisions of gas molecules.

This unit helps in understanding how gases behave under different physical conditions and why gas laws work at the molecular level. Concepts like RMS speed, molecular collisions, kinetic energy, and equipartition of energy form the foundation of thermal physics and thermodynamics.

Equation of State of an Ideal Gas

PV = nRT

The equation of state relates pressure, volume, temperature, and amount of gas in an ideal system.

An ideal gas is assumed to have negligible intermolecular forces and perfectly elastic collisions. Changes in pressure, volume, and temperature follow gas laws derived from this equation.

Work is done when a gas expands or is compressed, leading to energy transfer within the system.

Assumptions of Kinetic Theory of Gases

The kinetic theory is based on several assumptions about gas molecules and their motion.

Major assumptions include:

• Gas molecules move randomly in all directions

• Molecular collisions are perfectly elastic

• Intermolecular forces are negligible

• Volume of molecules is very small compared to the container volume

Pressure of a gas arises because molecules continuously collide with container walls.

Kinetic Interpretation of Temperature and RMS Speed

Temperature is related to the average kinetic energy of gas molecules. Higher temperature means greater molecular motion.

RMS (Root Mean Square) speed represents the effective speed of molecules in random motion.

The kinetic interpretation of temperature explains thermal energy at the molecular level.

Degrees of Freedom and Equipartition of Energy

Degrees of freedom represent the number of independent ways in which a molecule can store energy.

The law of equipartition of energy states that energy is equally distributed among all degrees of freedom.

This concept helps explain:

• Specific heat capacities of gases

• Energy distribution in molecules

• Thermal behaviour of monoatomic and diatomic gases

Mean Free Path and Avogadro’s Number

Mean free path is the average distance travelled by a molecule between two successive collisions.

Avogadro’s number gives the number of particles present in one mole of a substance.

These concepts are important for understanding molecular density, collision frequency, and gas behaviour at the microscopic level.

Kinetic Theory of Gases: Complete Study Resources By PW

For better preparation, you should revise formulas, solve numericals, and practice conceptual questions regularly. Below are the PW study resources for Kinetic Theory of Gases: