An isothermal process is a thermodynamic process during which the temperature of a system remains constant. In other words, the system undergoes a change in some of its properties (such as pressure, volume, or density), but the temperature throughout the entire process remains unchanged. This implies that there is no heat exchange with the surroundings during the process.
Daily Life Examples
Achieving perfect isothermal conditions in daily life is challenging, but certain processes and situations come close to approximating isothermal behavior. Here are some daily life examples where isothermal processes are approached:
- When a well-insulated room is maintained at a constant temperature using a heating or cooling system, the process of keeping the room temperature constant approaches isothermal conditions.
- Some modern cooking appliances, like sous-vide machines, use precise temperature control to keep the cooking water at a constant temperature. This creates an environment close to isothermal conditions for cooking.
- Efficient refrigeration systems work to maintain a constant temperature inside the refrigerator, which is crucial for preserving food. The slow and controlled heat exchange in the refrigeration cycle can be considered quasi-isothermal.
- When charging or discharging a well-insulated battery slowly, the temperature changes within the battery can be minimal, approximating an isothermal process.
- Laboratories often use water baths for experiments that require a constant temperature. By carefully controlling the heat input or removal, it is possible to approach isothermal conditions within the water bath.
Mathematical Terms
In mathematical terms, for an isothermal process, the change in internal energy (ΔU) of the system is zero. The equation that relates heat (Q), work (W), and internal energy change (ΔU) for a thermodynamic process is:
ΔU=Q−W
For an isothermal process (ΔU=0), this simplifies to:
Q=W
This means that any heat added to or removed from the system during an isothermal process is entirely converted into work or vice versa.
