Key Terms

adiabatic process

process during which no heat is transferred to or from the system

boundary

imagined walls that separate the system and its surroundings

closed system

system that is mechanically and thermally isolated from its environment

cyclic process

process in which the state of the system at the end is same as the state at the beginning

environment

outside of the system being studied

equation of state

describes properties of matter under given physical conditions

equilibrium

thermal balance established between two objects or parts within a system

extensive variable

variable that is proportional to the amount of matter in the system

first law of thermodynamics

the change in internal energy for any transition between two equilibrium states is $\text{Δ}{E}_{\text{int}}=Q-W$

intensive variable

variable that is independent of the amount of matter in the system

internal energy

average of the total mechanical energy of all the molecules or entities in the system

isobaric process

process during which the system’s pressure does not change

isochoric process

process during which the system’s volume does not change

isothermal process

process during which the system’s temperature remains constant

molar heat capacity at constant pressure

quantifies the ratio of the amount of heat added removed to the temperature while measuring at constant pressure

molar heat capacity at constant volume

quantifies the ratio of the amount of heat added removed to the temperature while measuring at constant volume

open system

system that can exchange energy and/or matter with its surroundings

quasi-static process

evolution of a system that goes so slowly that the system involved is always in thermodynamic equilibrium

reversible process

process that can be reverted to restore both the system and its environment back to their original states together

surroundings

environment that interacts with an open system

thermodynamic process

manner in which a state of a system can change from initial state to final state

thermodynamic system

object and focus of thermodynamic study