difference between isothemal and adiabatic process

Isothermal Process

• Occurs at a constant temperature; PV = Constant

Isothermal changes take place in an ideal gas (at temperature T)

Initially,

Pressure = P₁

Volume = V₁

Finally,

Pressure = P₂

Volume = V₂

At the intermediate stage,

Pressure = P

Work done for the entire process

• There is no change in the internal energy of an ideal gas in isothermal process.

• In isothermal expansion (V₂ > V₁), the gas absorbs heat and does work (W > 0)

• In isothermal compression (V₂ < V₁), work is done on the gas by the environment and heat is released.

Adiabatic Process

• During this process, no heat enters or leaves the thermodynamic system during the change.

• System is insulated from its surroundings.

PV^γ = Constant(1)

γ = Ratio of specific heats

• If an ideal gas undergoes a change adiabatically,

Initial state = P₁, V₁

Final state = P₂, V₂ 

Then,

The following graph shows the P-V curves of an ideal gas for two adiabatic processes connecting two isotherms.

Work done, 

From equation (1), we get

= Constant × 

= Constant × 

= Constant 

 is a constant

• Work done by the gas (W > 0); so T₂ < T₁

• Work done on the gas (W < 0); so T₂ > T₁