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# Thermodynamics Thermodynamics is the study of energy, its transformations, and its relation to matter. It is governed by a set of fundamental laws that dictate the behavior of energy in various systems. Here's an overview: ## Core Concepts ### Energy The capacity to do work. ### System The p...

# Thermodynamics Thermodynamics is the study of energy, its transformations, and its relation to matter. It is governed by a set of fundamental laws that dictate the behavior of energy in various systems. Here's an overview: ## Core Concepts ### Energy The capacity to do work. ### System The part of the universe under study. ### Surroundings Everything outside the system. ### Types of Systems * **Isolated:** No exchange of matter or energy with surroundings. * **Closed:** Exchange of energy but not matter. * **Open:** Exchange of both energy and matter. ### Thermodynamic Properties * **Intensive:** Independent of system size (e.g., temperature, pressure). * **Extensive:** Dependent on system size (e.g., volume, energy). ### State Functions Properties that depend only on the current state of the system, not on how it was achieved (e.g., internal energy, enthalpy, entropy, Gibbs free energy). ## The Laws  ### Zeroth Law If two systems are each in thermal equilibrium with a third, they are also in thermal equilibrium with each other. ### First Law The total energy of an isolated system is constant. Energy can be converted from one form to another, but cannot be created or destroyed. $\Delta U = Q - W$ * $\Delta U$ = Change in internal energy * $Q$ = Heat added to the system * $W$ = Work done by the system ### Second Law The entropy of an isolated system tends to increase over time. $\Delta S \geq 0$ * $\Delta S$ = Change in Entropy ### Third Law The entropy of a perfect crystal at absolute zero temperature is zero. $S = 0 \text{ at } T = 0K$ ## Thermodynamic Processes * **Isothermal:** Constant temperature. * **Adiabatic:** No heat exchange. * **Isobaric:** Constant pressure. * **Isochoric:** Constant volume. ## Enthalpy (H) A measure of the total heat content of a system at constant pressure. $H = U + PV$ * $U$ = Internal energy * $P$ = Pressure * $V$ = Volume ## Entropy (S) A measure of the disorder or randomness of a system. $\Delta S = \frac{Q_{rev}}{T}$ * $Q_{rev}$ = Heat added in a reversible process * $T$ = Absolute temperature ## Gibbs Free Energy (G) A measure of the amount of energy available in a system to do useful work at constant temperature and pressure. $G = H - TS$ * $H$ = Enthalpy * $T$ = Absolute temperature * $S$ = Entropy ## Applications * **Engines:** Converting thermal energy into mechanical work. * **Refrigeration:** Transferring heat from a cold reservoir to a hot reservoir. * **Chemical Reactions:** Predicting spontaneity and equilibrium. * **Material Science:** Understanding phase transitions and material properties.