- In thermodynamics, a state function, state quantity, or a function of the state, is a property of a system that depends only on the initial and final state the system, not on the way in which the system acquired that state.
- A state function describes the equilibrium state of a system and thus also describes the types of system.
- The cyclic integral involving a state function is always zero.
- All the thermodynamics property satisfy the requirements of state function.
∆U = q + w change in thermodynamic energyS = qrev/T entropyH = U = PV enthalpyG = H – TS Gibb’s free energyA = U – TS Helmholtz free energy
Internal energy, enthalpy, entropy are the example of state functions.
- Path function depends on the path taken to reach that specific value, not on the initial and final state of that value.
- Path function needs multiple integral and limits of the integration in order to integrate.
- It is based on how the state of a system was established.
- Work, heat, arc length are the example of path function.