Introduction to Thermodynamics

Thermodynamics is the science of the flow of heat. The term itself comes from "thermo" meaning heat and "dynamics" meaning the motion of heat. This subject was largely developed during the Industrial Revolution, beginning in the 1800s.

Historical Context

• Industrial Revolution: Key developments included taming of steel, generating power by burning fossil fuels, and the onset of problems like CO2 emissions and global warming.
• Arrhenius: Calculated the impact of CO2 on climate in the late 1800s, predicting problems in 2,000 years, although exponential growth in CO2 has accelerated this timetable.

Universality of Thermodynamics

• Biological Systems: Burning calories, creating heat, ATP usage.
• Mechanical Systems: Cars, boats, etc., moving and converting energy.
• Astrophysics: Stars, black holes—all involve moving and converting heat.
• Economics: Concepts of non-equilibrium thermodynamics applied to market crashes.

Development of Thermodynamics

• Empirical Foundation: Developed before the understanding of atoms/molecules, based on macroscopic properties of matter. Post-atomic era rationalizes it through statistical mechanics.
• Four Laws of Thermodynamics: Summarized empirical observations turned into laws.

The Four Laws of Thermodynamics

1. Zeroth Law: Defines temperature, the "common-sense law."
2. First Law: Defines energy and the concept of energy conservation, known as the "You can break even" law.
3. Second Law: Defines entropy and the direction of time; "You can't break even except at zero degrees Kelvin" law.
4. Third Law: Gives a numerical value to entropy; "You can't get to zero degrees Kelvin" law.

System Definitions

• System: The part of the universe being studied (e.g., a cup of coffee, an organism).
• Surroundings: Everything else outside the system.
• Boundary: The surface separating the system from its surroundings, which can be real or imaginary.

Types of Systems

• Open System: Allows mass and energy to flow through the boundary (e.g., a person).
• Closed System: Allows the transfer of energy but not mass.
• Isolated System: No mass or energy can flow through the boundary.

Describing Systems

• Macroscopic Variables: Pressure, temperature, volume, number of moles, mass, etc.
• Homogeneous vs. Heterogeneous Systems: One phase vs. multiple phases (e.g., coffee vs. ice water).
• Equilibrium: Properties don’t change in time or space; critical in thermodynamics.
• Components: Number of distinct molecules in the system.

Properties of Systems

• Extensive Properties: Scale with the size of the system (e.g., volume, mass).
• Intensive Properties: Do not scale with the size of the system (e.g., temperature).
• State Variables: Describe equilibrium states, independent of the system's history.
• Describing Equilibrium States: Use of chemical notation to succinctly describe states.

Path and Process in Thermodynamics

• Path: Sequence of states going from the initial to the final state; defines how energy transformations are handled.
• Reversible Path: Equilibrium maintained throughout the process.
• Irreversible Path: Equilibrium not maintained over the process, typically involving energy dissipation.

Special Paths and Processes

• Adiabatic: No heat transferred between system and surroundings.
• Isothermal: Constant temperature.
• Isobaric: Constant pressure.

The Zeroth Law of Thermodynamics

• Thermal Equilibrium: No heat flow between objects at the same temperature.
• Transitive Property of Thermal Equilibrium: If A is in thermal equilibrium with B, and B is in thermal equilibrium with C, then A is in thermal equilibrium with C.
• Defining Temperature: Allows the use of thermometers to measure and compare temperatures.

Measurement of Temperature

• Substance and Property: Volume, resistivity, and other properties change with temperature.
• Temperature Scales: Different scales such as Celsius, Fahrenheit, and Kelvin, with defined reference points and interpolation schemes.

Conclusion

• Understanding these basic concepts and definitions is crucial for solving thermodynamic problems and appreciating the universal applicability of thermodynamic principles.