Non-equilibrium thermodynamics

Definition

Non-equilibrium thermodynamics is the branch of thermodynamics that deals with systems that are not in thermodynamic equilibrium, focusing on the flow of energy and matter and the processes that drive these flows. It describes how systems evolve over time when they are subject to external forces or gradients, highlighting phenomena such as entropy production and the irreversible nature of certain processes.

5 Must Know Facts For Your Next Test

1. Non-equilibrium thermodynamics is crucial for understanding natural processes like heat transfer, diffusion, and chemical reactions that occur far from equilibrium conditions.
2. It emphasizes that entropy production is a key aspect of non-equilibrium states, as systems evolve towards equilibrium while producing entropy.
3. The Onsager Reciprocal Relations provide a foundation for predicting how systems respond to gradients in temperature, concentration, and pressure in a non-equilibrium state.
4. Non-equilibrium thermodynamics also applies to biological systems, where energy flows and chemical reactions drive metabolic processes essential for life.
5. This field relies on various approximations, including linear response theory, which simplifies the analysis of complex non-equilibrium systems under small deviations from equilibrium.

Review Questions

• How does non-equilibrium thermodynamics explain the flow of energy and matter in systems that are not at equilibrium?
  • Non-equilibrium thermodynamics explains that energy and matter flow due to gradients or differences within a system. For instance, heat flows from areas of high temperature to low temperature, while substances diffuse from regions of high concentration to low concentration. These flows result in changes in the system over time, and are driven by the tendency of systems to evolve towards equilibrium while simultaneously producing entropy.
• Discuss the importance of entropy production in non-equilibrium thermodynamics and its implications for real-world processes.
  • Entropy production plays a fundamental role in non-equilibrium thermodynamics as it quantifies the irreversibility of processes. In real-world scenarios, such as chemical reactions or heat engines, understanding how much entropy is generated helps predict efficiency and performance. The higher the rate of entropy production, the more irreversible the process becomes, impacting both energy conservation and system stability during transitions.
• Evaluate the significance of Onsager Reciprocal Relations in predicting the behavior of non-equilibrium systems.
  • Onsager Reciprocal Relations are significant because they provide a framework for understanding how different thermodynamic forces affect one another in non-equilibrium systems. By establishing connections between fluxes (like heat flow) and gradients (like temperature differences), these relations help predict responses under varied conditions. This predictive capability is vital for designing efficient industrial processes, optimizing energy conversion systems, and understanding biological mechanisms at a molecular level.

Related terms

Entropy Production: The measure of the amount of energy that is unavailable to do work during a thermodynamic process, reflecting the degree of irreversibility in a system.

Onsager Reciprocal Relations:

Mathematical relationships that describe how thermodynamic fluxes and forces are related in non-equilibrium systems, showing that the response to one gradient affects the response to another.

Irreversible Processes: Processes that cannot be reversed without leaving a change in the system and its surroundings, often associated with an increase in entropy.