HyperLink HyperLink

Featured Report
Subject:

Entropy
Thermodynamics The classical Carnot heat engine Book:Thermodynamics Classical Statistical Chemical Equilibrium / Non-equilibrium Zeroth First Second Third State Equation of state Ideal gas Real gas Phase / State of matter Equilibrium Control volume Instruments Processes Isobaric Isochoric Isothermal Adiabatic Isentropic Isenthalpic Quasistatic Polytropic Free expansion Reversibility Irreversibility Endoreversibility Cycles Heat engines Heat pumps Thermal efficiency Property diagrams Intensive and extensive properties Functions of state (Conjugate variables in italics) Temperature / Entropy Introduction to entropy Pressure / Volume Chemical potential / Particle number Vapor quality Reduced properties Process functions Work Heat Specific heat capacity  Compressibility  Thermal expansion  Property database Carnot's theorem Clausius theorem Fundamental relation Ideal gas law Maxwell relations Onsager reciprocal relations Bridgman's thermodynamic equations Table of thermodynamic equations Free energy Free entropy Internal energy Enthalpy Helmholtz free energy Gibbs free energy Philosophy Entropy and time Entropy and life Brownian ratchet Maxwell's demon Heat death paradox Loschmidt's paradox Synergetics History General Heat Entropy Gas laws "Perpetual motion" machines Theories Caloric theory Vis viva Theory of heat Mechanical equivalent of heat Motive power Key publications "An Experimental Enquiry Concerning ... Heat" "On the Equilibrium of Heterogeneous Substances" "Reflections on the Motive Power of Fire" Timelines Thermodynamics Heat engines Art Maxwell's thermodynamic surface Education Entropy as energy dispersal Bernoulli Carnot Clapeyron Clausius Carathéodory Pierre Duhem Gibbs von Helmholtz Joule Maxwell von Mayer Onsager Rankine Smeaton Stahl Thompson Thomson (Baron Kelvin) Waterson saha v t e Entropy articles Introduction History Classical Statistical In thermodynamics, entropy (usual symbol S) is a measure of the number of specific ways in which a thermodynamic system may be arranged, often taken to be a measure of disorder, or a measure of progressing towards thermodynamic equilibrium. The entropy of an isolated system never decreases, because isolated systems spontaneously evolve towards thermodynamic equilibrium, which is the state of maximum entropy.The change in entropy (?S) was originally defined for a thermodynamically reversible process as:,which is found from the uniform thermodynamic temperature (T) of a closed system dividing an incremental reversible transfer of heat into that system (dQ). The above definition is sometimes called the macroscopic definition of entropy because it can be used without regard to any microscopic picture of the contents of a system. In thermodynamics, entropy has been found to be more generally useful and it has several other formulations. Entropy was discovered when it was noticed to be a quantity that behaves as a function of state, as a consequence of the second law of thermodynamics. Entropy is an extensive property, but it is often given intensively in the form of specific entropy, the entropy per unit mass, or molar entropy, the entropy per mole.The absolute entropy (S rather than ?S) was defined later, using either statistical mechanics or the third law of thermodynamics.In the modern microscopic interpretation of entropy in statistical mechanics, entropy is the amount of additional information needed to specify the exact physical state of a system, given its thermodynamic specification. Understanding the role of thermodynamic entropy in various processes requires understanding how and why that information changes as the system evolves from its initial condition. It is often said that entropy is an expression of the disorder, or randomness of a system, or of our lack of information about it. The second law is now often seen as an expression of the fundamental postulate of statistical mechanics via the modern definition of entropy.
Created By: System
Join To Create/Save Reports
Forgot Password

Related Reports