## Isothermal Process

If the thermodynamic system is perfectly conducting to the surrounding and undergoes a physical process in such a way that its temperature remains constant throughout, then the process is an isothermal process.

It may be defined as:

A change in pressure & volume of gas without any change in its temperature is called an isothermal process or isothermal operation”.

For such a process, the temperature of the system remains constant,

i.e. T = constant

&  △T = 0

### Essential Conditions for Perfect Isothermal Process:

1. The wall of the container must be perfectly conducting.

2. The process of compression or expansion should be so slow so as to provide time for exchange of heat.

### The equation of an Isothermal Change:

Using the equation of Vanderwall’s gas:
PV = nRT
If n = 1mol, R = constant, T= constant
then,     PV = K(constant)
This is an equation of Isothermal Change.

### Specific Heat Capacity of Isothermal Change:

In an Isothermal change, T = constant

then △T = 0

As the specific heat of the gas is given by:
C = △Q/m△T

∵  △T =0     ∴ C = ∞

Therefore, in an Isothermal process, the specific heat of the gas is infinite.