Thermodynamics Laws and Formulas

Study Notes

Zeroth Law of Thermodynamics: If two systems are in thermal equilibrium with a third system, then they are also in thermal equilibrium with each other.
First Law of Thermodynamics (Law of Energy Conservation): Energy cannot be created or destroyed, only converted from one form to another.
- Mathematically represented as: ΔE = Q - W
- ΔE: change in energy
- Q: heat added to the system
- W: work done on the system
Second Law of Thermodynamics: The total entropy of an isolated system always increases over time, except in reversible processes.
- Entropy (S) is a measure of disorder or randomness
- Mathematically represented as: ΔS = ΔQ / T
- ΔS: change in entropy
- ΔQ: heat added to the system
- T: temperature
Third Law of Thermodynamics: As the temperature of a system approaches absolute zero, the entropy of the system approaches a minimum value.

Closed System: A system that does not exchange matter with its surroundings, but can exchange energy.
Open System: A system that can exchange both matter and energy with its surroundings.
Isolated System: A system that does not exchange matter or energy with its surroundings.

Isothermal Process: A process that occurs at a constant temperature.
Adiabatic Process: A process that occurs without heat transfer between the system and its surroundings.
Isobaric Process: A process that occurs at a constant pressure.
Isochoric Process: A process that occurs at a constant volume.

Internal Energy (U): The total energy of a system, including kinetic energy, potential energy, and potential energy associated with the interactions between particles.
Enthalpy (H): A measure of the total energy of a system, including internal energy and the energy associated with the pressure and volume of a system.
Entropy (S): A measure of the disorder or randomness of a system.
Free Energy (G): A measure of the energy available to do work in a system.

Ideal Gas Law: PV = nRT
- P: pressure
- V: volume
- n: number of moles
- R: gas constant
- T: temperature
Carnot Cycle: A theoretical cycle that represents the maximum efficiency of a heat engine.

Zeroth Law of Thermodynamics: Thermal equilibrium is a transitive property, meaning that if two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other.
First Law of Thermodynamics (Law of Energy Conservation): Energy cannot be created or destroyed, only converted from one form to another, with the change in energy (ΔE) equal to the heat added to the system (Q) minus the work done on the system (W).
Second Law of Thermodynamics: The total entropy of an isolated system always increases over time, except in reversible processes, with entropy (S) being a measure of disorder or randomness and the change in entropy (ΔS) equal to the heat added to the system (ΔQ) divided by the temperature (T).
Third Law of Thermodynamics: As the temperature of a system approaches absolute zero, the entropy of the system approaches a minimum value.

Closed System: A system that does not exchange matter with its surroundings, but can exchange energy.
Open System: A system that can exchange both matter and energy with its surroundings.
Isolated System: A system that does not exchange matter or energy with its surroundings.

Isothermal Process: A process that occurs at a constant temperature.
Adiabatic Process: A process that occurs without heat transfer between the system and its surroundings.
Isobaric Process: A process that occurs at a constant pressure.
Isochoric Process: A process that occurs at a constant volume.

Internal Energy (U): The total energy of a system, including kinetic energy, potential energy, and potential energy associated with the interactions between particles.
Enthalpy (H): A measure of the total energy of a system, including internal energy and the energy associated with the pressure and volume of a system.
Entropy (S): A measure of the disorder or randomness of a system.
Free Energy (G): A measure of the energy available to do work in a system.

Ideal Gas Law: PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature.
Carnot Cycle: A theoretical cycle that represents the maximum efficiency of a heat engine.