Some important terms and types of systems
Here are some more important terms which are found frequently in the subject area of thermodynamics and various types of system.
Change of state of system: When one or more properties of the system like pressure, temperature, volume changes, the state of system changes.
Path of change of state: The succession of states through which the system undergoes change to reach the final state is called as the path of change of state of the system.
Homogeneous system: The system that has single or uniform phase such as like solid or liquid or gaseous is called as homogeneous system.
Heterogeneous system: The system that has more than one phase i.e. the combination of solid, liquid and gaseous state is called as heterogeneous system.
Thermodynamics process: When the system changes from one thermodynamic state to the final thermodynamic state due to change in pressure, temperature, volume etc, the system is said to have undergone thermodynamic process. The various types of thermodynamic processes are: isothermal process, adiabatic process, isochoric process, isobaric process and reversible process.
Cyclic process: When the system undergoes a number of changes in states and returns back to the initial state, the system is said to have undergone cyclic process.
Isothermal process: The process during which the temperature of the system remains constant is called as isothermal process.
Adiabatic process: The process during which the heat content of the system remains constant i.e. no flow of heat takes place across the boundaries of system, the process is called as adiabatic process.
Isochoric process: In this process the volume of system remains constant.
Isobaric process: The process during which the pressure of the system remains constant, is called as isobaric process.
Reversible process: When the system undergoes changes infinitesimally slowly the changes can be reversed back, such a process is called as reversible process. During reversible process the system remains in equilibrium during the change of state of the system.
Enthalpy of the system: The total heat content of the system is called as enthalpy of the system. The units of enthalpy are same as heat viz. Joules and Calories.
Entropy of the system: It is the total energy inside the system, which is not available for work during thermodynamic process. It depends on the movement of the molecules inside the system. As the temperature of the system reduces its entropy also reduces. Entropy of the system is never negative.