Definitions for Thermodynamics -...

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Page 1: Definitions for Thermodynamics - chemistry.alanearhart.orgchemistry.alanearhart.org/resources/Handouts/defs-thermo-qr.pdf · Definitions for Thermodynamics Alan D. Earhart 5/16/2017

DefinitionsforThermodynamics

AlanD.Earhart 5/16/2017

Energy:Thecapacitytodoworkortransferheat.Enthalpy:Energychangeatconstantpressure.Entropy:Theamountofmoleculardisorderorrandomnessinasystem.FreeEnergy:G=H–TS ΔG=ΔH–TΔS ΔG0=ΔH0–TΔS0Heat:Theprocessofenergytransferfromonebodyorsystemtoanotherasaresultofadifferenceintemperature.LawsofThermodynamics FirstLaw:Energyisconserved.Itcanbeneithercreatednordestroyedinanisolatedsystem. SecondLaw:Inanisolatedsystem,naturalprocessesarespontaneouswhentheyleadtoan increaseinentropy. ThirdLaw:Theentropyofaperfectcrystalofanypuresubstanceapproacheszeroasthe temperatureofthecrystalapproaches0K. ZerothLaw:Whentwosystemsareinequilibriumwithathird,thosetwosystemsarein equilibriumwitheachother.SpontaneousProcess:Aprocessthatproceedsonitsownwithoutanycontinuousexternalinfluence.StateFunction:Apropertyofasystemthatisdeterminedonlybythestateorconditionofthesystem.StandardConditions:Solutions1mol/L;pressure1atm;ifthetemperatureisnotspecified,25°C.StandardState:Themoststableformofasubstanceunderstandardconditions.Surroundings:Everythingbutthesystem.System:Portionoftheuniversebeingstudied.Temperature:Thepropertyofabodyorregionofspacethatdetermineswhetherornottherewillbeanetflowofheatintooroutofitfromaneighboringbodyorregionandinwhichdirectiontheheatwillflow.