SYSTEM AND ITS SURROUNDINGS
System: A system in thermodynamics refers to that part of universe in which observations are made.
Surroundings: The surroundings include everything other than the system.
TYPES OF SYSTEM
1. Open system
- In an open system, there is exchange of energy and matter between system and surroundings.
2. Closed system
- In a closed system, there is no exchange of matter, but exchange of energy is possible between system and surroundings.
3. Isolated system
- In an isolated system, there is no exchange of energy or matter between the system and the surroundings.
THE STATE OF THE SYSTEM
The state of a thermodynamic system is described by its measurable or macroscopic (bulk) properties. The state can be described by quoting its pressure, volume, temperature, etc. Variables like these are called state variables or state functions because their values depend only on the state of the system and not on how it is reached.
THE INTERNAL ENERGY AS A STATE FUNCTION
The internal energy of a system may change due to heat passing in or out of the system, work done on or by the system, or if matter enters or leaves the system.
Entropy is a measure of disorder or randomness in a system.