Chapter 12: Kinetic Theory

Assumptions of Kinetic Theory of Gas

(i) The molecules of an ideal gas are in a state of never stopping random motion. They move in all directions with different speeds., (of the order of 500 m/s) and obey Newton’s laws of motion.

(ii) The molecules of an ideal gas do not exert any force of attraction or repulsion on each other, except during collision.

(iii) The molecules of an ideal gas moves along a straight line between two successive collisions and the average straight distance covered between two successive collisions is called the mean free path of the molecules.

(iv) The size of ideal gas molecules is very small as compared to the distance between them.

(v) The molecules of an ideal do not exert any force of attraction or repulsion on each other.

Pressure of an ideal gas is given by, $P=\frac{1}{3}\rho _{gas}v_{rms}^{2}$

Ideal Gas: That gas which strictly obeys the gas laws, (such as Boyle’s Law, Charles’, Gay Lussac’s Law etc.)

Real Gas: All gases are referred to as real gases. All real gases showes the ideal gas behavior at low pressures and temperatures high enough, where they cannot be liquified

Gay Lussac’s Law/Boyle’s Law:  PV = constant for given mass of gas at constant temperature.

Charle’s Law: $PV\propto T$ If P is constant, $V\propto T$.

Constant Volume Law:$PV\propto T$, If V is constant, $P\propto T$

Avogadro’s Law: Equal volumes of all ideal gases existing under the same conditions of temperature and pressure contain equal number of molecules.

Ideal Gas Equation: $PV=Nk_{b}T$

Speed of Gas Molecules: