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Question 1

Non- equilibrium thermodynamics

Answer 1

Deals with states and processes in systems that are not in thermodynamic equilibrium. In some cases these states and processes are stable for certain period of time in open systems: Steady state and Dissipative structures.

Question 2

Equilibrium state

Answer 2

Values of all variables of the system are constant and equal in each point of the system and in the surroundings ⇒ no gradients, no structure, the system is homogeneous = HIGH ENTROPY

Question 3

Non-equilibrium state

Answer 3

Values of all variables of the system are not constant and not equal in each point of the system and in the surroundings ⇒ gradients, structure, the system is inhomogeneous = LOW ENTROPY

Question 4

Equilibrium process

Answer 4

Transition between two equilibrium states. The system is reversible; can return to the initial state spontaneously.

Question 5

Non-equilibrium process

Answer 5

At least one state is a non-equilibrium state. The system is irreversible; cannot return to the initial state spontaneously.

Question 6

Onsager’s relation

Answer 6

= A gradient is the driving force of a flow (flux) in non-equilibrium processes:

Question 7

Steady (stationary) state

Answer 7

All state variables are constant in spite of ongoing processes
Jin = -Jex ⇒ constant values of all parameters of the system

Question 8

Prigogine’s theorem

Answer 8

In a steady (stationary) state, the rate ot production of entropy (ΔS/Δt)in inside the system is always positive but has a minimal value. ⇒ The consumption of free energy is minimal.

Question 9

Dissipative structure

Answer 9

• non-equilibrium steady state in open systems
• non-linear processes Li = f(Xi)
• super critical values of gradients in the system
• cooperative behaviour of fluxes

Example: Benard cells, fire, turbines, ect.