INTERNAL ENERGY(E/U) AS A STATE FUCTION

Every system having some quantity of matter is associated with a definite amount of energy, called internal energy. Internal energy is stored in different forms inside the molecule.

 U = U_Kinetic + U_Potential + U_Electronic + U_nuclear + .....

Note :

1.U is a state function & is an extensive property.

                   U = U_final – U_initial

2. It does not include kinetic energy of motion of system as a whole or its potential energy due  to its position.

3. ∆E = q_V, heat supplied to a gas at constant volume, since all the heat supplied goes to

Increase the internal energy of the gas.

4. For a given system, if U is a function of T and Volume :

              

5. For isochoric process: dV = 0                           

6. For an ideal gas, change in internal energy with change in volume at constant temperature is zero.i.e.                           

“Internal energy is stored in the molecular motion and capacity to store energy depends upon degree of freedom of molecules”