In thermodynamics, the system, surroundings, and universe are fundamental concepts used to describe and analyze energy exchanges and transformations. Here’s what they mean
Thermodynamic System
A thermodynamic system is the specific part of the universe we are studying or analyzing. It is separated from the rest of the universe by boundaries, which can be real or imaginary.
Basically a thermodynamic system is classified in to three types : open, closed and isolated.
Also read : Types of thermodynamic system.
Surroundings:
The surroundings are everything outside the system that can interact with it. The system and surroundings together make up the universe.
- Surroundings play a critical role in energy exchange with the system.
- Example: For a hot cup of coffee (system), the air around it, the cup, and the table are the surroundings that absorb heat from it.
Universe:
The universe is the combination of the system and its surroundings.
In simple terms,
Universe = System + Surroundings.
- In thermodynamics, we often focus on the system and its immediate surroundings because the universe is too vast to study comprehensively.
- Energy Conservation Principle: The total energy of the universe is constant (First Law of Thermodynamics). While energy can be transferred between the system and surroundings, it is neither created nor destroyed.
Boundary
The boundary separates the system from its surroundings. It can be:
- Rigid or Movable: Determines if the system can change volume.
- Diathermal or Adiabatic: A diathermal boundary allows heat transfer, while an adiabatic boundary does not.
- Real or Imaginary: Sometimes, boundaries are conceptual to simplify the analysis.
The following image shows that clear explanation of thermodynamics system, surroundings, boundary and universe.
Real life example:
Hot coffee in a flask:
- System: Hot coffee and steam inside the flask.
- Surroundings: The flask, air, and everything else outside the coffee.
- Boundary: flask.
- Universe: The Hot coffee (system) + the flask(boundary) and air (surroundings).
Understanding the interplay between these elements allows scientists and engineers to model processes like heat engines, refrigeration, and chemical reactions.