The state of a substance is the condition of a system at a specific time and all properties at that time that can be measured or calculated.
Procedure to Define State
- Identify the phase
- Subcooled liquid
- Saturated liquid
- Two-phase mixture
- Saturated vapor
- Superheated vapor
- Find two independent properties
- Pressure, temperature, internal energy, enthalpy, etc…
- Then, there will be a process (such as isobaric heating) leading to another state