Laws of Thermodynamics, Summaries of Thermodynamics

Download Laws of Thermodynamics and more Summaries Thermodynamics in PDF only on Docsity! Laws of Thermodynamics Thermodynamics: (developed in 19th century) phenomenological theory to describe equilibrium properties of macro- scopic systems based on few macroscopically measurable quantities thermodynamic limit (boundaries unimportant) state variables / state functions: describe equilibrium state of TD system uniquely intensive: homogeneous of degree 0, independent of system size extensive: homogeneous of degree 1, proportional to system size intensive state variables serve as equilibrium parameters Laws of Thermodynamics state variables / state functions: intensive extensive T temperature p pressure H magnetic field E electric field µ chemical potential S entropy V volume M magnetization P dielectric polarization N particle number conjugate state variable: combine together to an energy T S, pV, HM, EP, µN unit [energy] Laws of Thermodynamics Equilibrium parameters: intensive state variables can serve as equilibrium parameters Temperature (existence: 0th law of thermodynamics ) T1 T2 colder characterizes state of TD systems warmer „bridge“ heat flow T T „bridge“ equilibrium T1 < T < T2Fick‘s law heat current temperature gradient no heat flow Laws of Thermodynamics Equilibrium parameters: intensive state variables can serve as equilibrium parameters Temperature (existence: 0th law of thermodynamics ) T1 T2 colder characterizes state of TD systems warmer „bridge“ heat flow T T „bridge“ equilibrium other equilibrium parameters: pressure p chemical potential µ no heat flow equilibrium parameter constant everywhere in TD system Laws of Thermodynamics Equations of state: consider TD system described by state variables subspace of equilibrium states: equation of state (EOS) Ideal gas: Boltzmann constant thermodynamic EOS Laws of Thermodynamics 1st law internal energy ideal gas (single atomic): (equipartition) Specific heat: constant V caloric EOS Laws of Thermodynamics 1st law internal energy ideal gas (single atomic): Specific heat: constant p (equipartition) caloric EOS Laws of Thermodynamics 1st law internal energy ideal gas (single atomic): Specific heat: ideal gas: and (equipartition) caloric EOS Laws of Thermodynamics 2nd law entropy ideal gas: V1 V2 V1 V2 reversible isothermal process dU=0 p A B coupled to work reservoir irreversible process increase of entropy waste of potential energy A B Laws of Thermodynamics 2nd law application to gas: dS exact differential S(U,V) caloric EOS thermodynamic EOS Laws of Thermodynamics Thermodynamic potentials natural state variables convenient simple relations and response functions: specific heat adiabatic compressibility dS=0 internal energy (gas) U(S,V) Laws of Thermodynamics Thermodynamic potentials natural state variables convenient simple relations other variables: (S,V) (T,V) Helmholtz free energy (gas) F(T,V) Legendre transformation Maxwell relation Laws of Thermodynamics Thermodynamic potentials natural state variables convenient simple relations Enthalpy (gas) H(S,p) Maxwell relation Gibbs free energy (gas) G(T,p) Maxwell relation Laws of Thermodynamics Equilibrium condition entropy: general in equilibrium S maximal closed system: dU=dV=0 U,V fixed variables fixed variables T,V F minimal T,p G minimal S,V U minimal S,p H minimal potential