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A thermodynamic process during which the pressure remains constant. When heat is transferred to or from a gaseous system, a volume change occurs at constant pressure. This thermodynamic process can be illustrated by the expansion of a substance when it is heated. The system is then capable of doing an amount of work on its surroundings. The maximum work is done when the external pressure of the surroundings on the system is equal to the pressure of the system. See Isometric process, Polytropic process
a process that occurs in a physical system with a constant external pressure.
The simplest examples of isobaric processes are the heating of water in an open vessel and the expansion of a gas in a cylinder with a freely moving piston. In both cases the pressure is equal to atmospheric pressure. In an isobaric process the volume of an ideal gas is proportional to the temperature (Gay-Lussac law). The specific heat of a system is greater in an isobaric process than in an isochoric process (that is, with constant volume), since in an isobaric process not only is the system heated as a result of the quantity of heat fed to it, but it performs work. The work performed by an ideal gas in an isobaric process is equal to pΔ V, where p is the pressure and A V is the change in volume.