Online Short Notes 1 => CHAPTER 5 STATES OF MATTER 11th Class

Check out Online Short Notes 1 => CHAPTER 5 STATES OF MATTER 11th Class for CBSE 11th Class to prepare for CBSE Board, CSIR NET, CBSE NEET, GRE etc.


Change in state: It is over all effect of Inter-molecular forces, molecular Interaction Energy & thermal energy.

Measurable properties of gases : P,V, T, n, Viscosity, specific heat are some measurable properties.


Gas Laws : The quantitative relationship b/w any two of the variables (V, n, P,T) when other two are constant.


Boyle‘s Law : The pressure of fixed mass of gas varies inversely with the volume

At constant Temperature:

P α 1/V                (  n, T const.)


P₁V₁ = P₂ V₂

Charle’s Law : At constant P, the volume of fixed amount of gas varies directly with its absolute temperature.

V α T or

V /T    is constant,

V₁/T₁   =   V₂/T₂

Gay lussac’s Law : At constant V, The pressure
of fixed amount of gas varies directly with its absolute temperature.


P α T or

P/T is  constant

P₁/T₁  =  P₂/T₂


Ideal gas equation : The relationship b/w P, V and T by Gas Laws

PV= nRT.


Avogadro‘s Law : At given T and P, the volume of gas varies directly to the amount of gas .

V α n           ( P, T constant)


Dalton‘s Law of partial pressure : The pressure exerted by a mixture of non reacting gases is equal to the sum of their partial pressure at constant (V,T).

P (total ) = P1 + P2 + P3 + ………. (T, V, constant)

Kinetic Molecular theory :
=> Gases consist of large number of identical particles (atoms or molecules) that are so small that the actual volume of the molecules is negligible in comparison to the empty space between them.


=> There is no force of attraction between the particles of a gas at ordinary temperature and pressure.


=> Particles of a gas are always in constant and random motion


=> Pressure is exerted by the gas as a result of collision of the particles with the walls of the container.


=> Collisions of gas molecules are perfectly elastic


=> At any particular time, different particles in the gas have different speeds and hence different kinetic energies


=> Average kinetic energy of the gas molecules is directly proportional to the absolute temperature

Real Gases : The gases which deviates from Ideal behavior at higher pressure and low temperature b/c of force of attraction b/w molecules increases .


Compressibility factor (Z) : It determine extent of devation of real gases from Ideal gas behavior :

Z   =    PV  / n.R.T.            

For ideal gas Z=1, 

For Non-ideal gas      

Z< 1,     Z > 1

Vander waal‘s Equation :


( P   +   n² a  / V  )  ( V  - nb ) = nRT

Critical Temperature (T_c) :  The temperature above which a gas cannot be liquefied whatever high pressure may be


Critical Pressure : The minimum pressure required to liquity a gas at its critical temperature.


Critical Volume : The volume of 1 mole of gat at Tc, Pc.


Super cooled liquids : The liquids which are cooled to a temperature below its freezing point without freezing .

Elastic Collision : The collisions in which no loss of K.E. only there is transfer of energy.


Vapour pressure : The equilibrium pressure by vapour of liquid in a container at given temperature (T)


At higher altitude : The b.p. of water decreases b/c the atmospheric pressure is less than one atmosphere.


Surface Tension (V) : It is force acting per unit length perpendicular to the line drawn on the surface : (N-m^-1) :

It decreases with increases in T, it increases with increase in external pressure, b/c of it falling drops of liquid are spherical, liquid in capillary tube rises.


Viscosity (η) : It is resistance offered to the flow of liquid due to friction b/w layer of fluids .

F =  η.A. ( dv / dn )


Effect of T & P on viscosity : It decreases with increase in T, and increases with increase in P.


Low M.P. & B.P. of molecular liquids : It is due to low magnitude of molecular interaction energy.