2. Thermodynamics
Heat:
Heat is a form of energy.
Thermodynamics:
A branch of physics which deals with the energy and transformation of heat due to
matter into other forms of energy.
3. Kinetic theory of gases
A finite volume of gas contain large numbers of atoms and molecules.
The size of molecule is much smaller than the separation between molecules.
Gas molecules are in random position and may change their direction after every
collision.
Molecules do not exert force on each other except collision.
The collision of molecules with themselves and with the wall of cylinder is perfectly
elastic.
4. Effect of pressure and temperature
When gas molecules collide, they exert pressure on each other. In other words they
increase their Kinetic energy. So we can say that
P K.E
Also it increases temperature as well. so,
T K.E
5. First law of thermodynamics
Statement:
In any thermodynamics process, when heat Q is added to the system this energy appears
as an increase in internal energy stored in the system plus work done by the system on
its surroundings.
Q = ∆U + W
Example:
Bicycle pump
Human metabolism
6. Isothermal and adiabatic process
Isothermal process:
A process in which temperature remains constant.
Thus first law of thermodynamics:
∆U = 0 because temperature remains constant. i.e ∆T = 0
Q = W
Adiabatic process:
The process in which no heat enters or leaves the system.
i.e. Q = 0
So, 1st law of thermodynamics will be
Q = - ∆U
7. Molar specific heat of Gas
Definition:
The heat required to raise the temperature of one mole of gas, Called molar specific
heat of gas.
Molar specific heat of gas at constant Volume:
The heat required to raise the temperature of one mole of gas at constant volume
through 1K.
Molar specific heat of gas at constant pressure:
The heat required to raise the temperature of one mole of gas at constant pressure
through 1K.
Relation:
C 𝒑 − C 𝒗 = R
8. Second law of thermodynamics
Statement:
It is impossible to devise a process or system which may convert heat entirely into work
without leaving any change in the working system.
9. Entropy
Definition:
The change in state of the system under natural process is termed as Entropy.
Formula:
∆S = ∆Q / T