**Isothermal Processes**

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

It may be defined as

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

For such process, tempreture of the system remains constant,

i.e. T = constant

& △T = 0

i.e. T = constant

& △T = 0

**Essential Conditions for Perfect Isothermal Process :-**

**1**. The wall of 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.

**Equation of an Isothermal Change :-**

Using equation of Vanderwall’s gas

PV = nRT

If n = 1mol, R = constant, T= constant

PV = nRT

If n = 1mol, R = constant, T= constant

PV = K(constant)

This is equation of Isothermal Change.

**Specific Heat Capacity of Isothermal Change :-**

In an Isothermal change, T = constant

then △T = 0

then △T = 0

As, specific heat of gas is given by

C = △Q/m△T

∵ △T =0

∴ C = ∞

C = △Q/m△T

∵ △T =0

∴ C = ∞

Therefore, in an Isothermal change apecific heat of gas is infinite.