System and Surroundings
A system is the portion of the universe that we are interested in observing or manipulating. The rest of the universe is considered the surroundings.
Isolated systems (what is the result of this assumption?)
Isolated systems are not capable of exchanging energy or matter with their surroundings.
As a result, the total change in internal energy must be zero.
Examples of pseudo-isolated systems
A bomb calorimeter attempts to insulate a reaction from the surroundings to prevent energy transfer, and the entire universe can be considered an isolated system because there are no surroundings.
True isolated systems are not real
Closed systems
Closed systems are capable of exchanging energy, but not matter, with the surroundings.
Example of closed systems
The classic experiments involving gases in vessels with movable pistons are examples of closed systems.
Open systems
Open systems can exchange both matter and energy with the environment.
Examples of open systems
A boiling pot of water, human beings, and uncontained combustion reactions are all examples of open systems.
State functions
State functions are thermodynamic properties that are a function of only the current equilibrium state of a system.
In other words, state functions are defined by the fact that they are independent of the path taken to get to a particular equilibrium state.
Examples of state functions
The state functions include pressure (P), density (ρ), temperature (T), volume (V), enthalpy (H), internal energy (U), Gibbs free energy (G), and entropy (S)
Process functions
Process functions describe the path taken to get to from one state to another.
Examples of process functions
Work and heat