# Isothermal Process

on . Posted in Thermodynamics

Isothermal process is a thermodynamic process in which the temperature of a system remains constant throughout the process.  During an isothermal process, the system's temperature does not change, and it typically occurs slowly enough that the system can equilibrate with its surroundings at each stage of the process.

### Key Points about isothermal process

• Constant Temperature  -  The primary defining characteristic of an isothermal process is that the temperature of the system remains constant.  This is often achieved by allowing heat to flow into or out of the system to maintain the desired temperature.
• Slow Process  -  In practice, isothermal processes are conducted slowly to ensure that the system and its surroundings are always in thermal equilibrium.  This means that the system's pressure, volume, or other relevant properties change gradually to maintain the constant temperature.
• Ideal Gases  -  Ideal gases behave closely to isothermally when their conditions change gradually.  This is because in an ideal gas, pressure and volume are inversely proportional when the temperature is held constant, as described by the ideal gas law (PV = nRT).
• Work and Heat Exchange  -  During an isothermal process, work is done on or by the system, and heat is exchanged with the surroundings to maintain the constant temperature.  The total heat added or removed is equal to the work done by or on the system.

Mathematically, for an ideal gas undergoing an isothermal process, you can describe the relationship between pressure and volume using the Boyle's law.  This equation shows that as the volume of the gas increases, its pressure decreases, and vice versa, while keeping the temperature constant.  Isothermal processes are often represented on a P-V (pressure-volume) diagram as a hyperbolic curve, which is in contrast to adiabatic processes where there is no heat exchange, and the temperature changes with changes in pressure and volume.

It's important to note that achieving a truly isothermal process is often idealized, and in practice, it may be challenging to maintain a constant temperature perfectly.  However, engineers and scientists use well insulated systems and careful control of heat exchange to approximate isothermal conditions for various practical applications in fields such as chemistry, physics, and engineering.