Question

Define open system and closed system in thermodynamics

Answer 1

The space outside the thermodynamic system is known as the surroundings, a reservoir, or the environment. ... The walls of a closed system allow transfer of energy as heat and as work, but not of matter, between it and its surroundings. The walls of an open system allow transfer both of matter and of energy.

Answer 2

open system : open system is defined as the thermodynamic system in which mass as well as energy transfer takes place.

close system : close system is defined as the thermodynamic system in which only energy transfer takes place.

In a closed system, the mass inside is constant throughout a process. But in an open system, mass is not necessarily be constant. We can say that the volume is constant in an open system.