isothermális

Isothermális is a term used in thermodynamics and physical chemistry to describe a process or a state where the temperature remains constant. When a system undergoes an isothermal process, heat may be exchanged with its surroundings, but this exchange is precisely balanced to maintain a uniform and unchanging temperature throughout. This is distinct from adiabatic processes, where no heat is exchanged at all, and isobaric processes, where pressure is held constant.

In an isothermal expansion of a gas, for instance, the gas absorbs heat from its environment as it does work, preventing its temperature from dropping. Conversely, during an isothermal compression, the gas releases heat to its surroundings as work is done on it, preventing its temperature from rising. Many real-world processes approximate isothermal conditions when they occur slowly enough to allow for efficient heat transfer, or when a system is in excellent thermal contact with a large reservoir at a constant temperature. The concept of isotherms is also crucial in understanding phase transitions, such as melting or boiling, which occur at constant temperatures under specific pressures.