Määritelmä
Kun järjestelmän lämpötila, paine, tilavuus, aineen tila, aineen määrä, vaihe, eri energiat jne. ovat vakioita, sanomme, että järjestelmä ei ole tilassa (tila).
Whenthesystemchangesfromonestate(initialstate)toanotherstate(finalstate),wesay:aprocesshasoccurred.Theprocessinwhichthetemperaturesoftheinitialstateandthefinalstateareequaliscalledanisothermalprocess.Theprocessinwhichthepressuresoftheinitialstateandthefinalstateareequaliscalledanequalpressureprocess.Theprocessinwhichthevolumeoftheinitialstateandthefinalstateareequaliscalledanisovolumetricprocess.
Idealizationisanimportantscientificmethod.Whenstudyingactualgases,idealgasescanbeused.Thestudyofmechanicscanalsorelyonanidealprocesswithoutfriction.Thermodynamicsalsoassumesanidealprocess,calledareversibleprocess.Areversibleprocessisaprocessthatapproachestheequilibriumstateinfinitely.Thereversibilitymentionedhereisnotaprocessofbothforwardandreverse,whichiscommonlyunderstood,butfromtheinitialstatetothefinalstate,andthenfromthefinalstatetotheinitialstate,acycle,whichisgoodforthesystemandtheenvironment,withoutleavingbehindAny"trace".Whatis"trace"?Thisisexactlywhatwewanttofigureout,anditwillbeexplainedslowlybelow.Wejustwanttosayherethatthisthermodynamicallyreversibleprocessisanidealprocess,justastheactualgasisnotanidealgas,andjustastheactualprocessofdoingmechanicalworkdoesnothaveanyfrictionanddoesnotexist,thedischargeoftheprimarybatteryisimpossible.Littleelectricenergyisnottransformedintothermalenergy,etc.,like"idealization".Allactualprocessesareirreversibleprocesses.Theidealthermodynamicallyreversibleprocessdoesnotexist,butitisalimitprocess,whichisextremelymeaningfulfordiscussingthermodynamics.
Therearetwoidealprocessesinthermodynamics,oneisthereversibleexpansionofanidealgas,andtheotheristhereversibledischargeofthegalvanicbattery.Theyarebothidealprocessesandcannotreallyexist,buttheworktheydoTheyarethelimitvaluesofexpansionworkandusefulwork.Theworkdoneinallactualprocessescannotreachorexceedtheworkdoneinthereversibleprocessnumerically.
Asian tila
Kiinteä
Nestemäinen
Kaasumainen
Plasma
Boaikondensoitunutta ainetta
Fermionin kondensoitunut aine
Neutronitila
suprajohtava tila
Superfluidstate
Supersolidstate
Spontaani prosessi ja ei-spontaani prosessi
Thermodynamicsalsodividestheprocessintospontaneousandnon-spontaneousprocesses.Spontaneousprocessesareprocessesthatoccurnaturallyinnature,andgowiththeflow;non-spontaneousprocessesareprocessesthatdonotoccurnaturally.Examplesareasfollows:
Lämpövirtaa korkeasta lämpötilasta matalaan lämpötilaan
Vesi virtaa korkeilta vuorilta tasangoilta
Tuulivirtauskorkeasta paineesta matalapaineeseen
Virrat korkeasta potentiaalista (positiivisesta)matalaan potentiaaliin (negatiiviseen)
Hydroxideunderpressureiscombinedintowaterandheatflowsfromlowtemperaturetohightemperature(refrigerator)
Vesi virtaa tasolta vuorelle (pumppu)
Airflowflowsfromlowpressuretohighpressure(compressor)
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Currentflowsfromlowelectricpotentialtohighelectricpotential(batterycharging)
Thedecompositionofwaterintohydrogenandoxygen(electrolysis)atnormaltemperatureandpressure
ThethermodynamicsprovethatinaclosedsystemIfaspontaneousprocessoccursintheprocess,thesystemmusthavethepossibilityofdoingusefulworktotheenvironment.Conversely,ifusefulworkmustbedonetoaclosedsystem,aprocesswilloccurinthesystem,andthisprocessmustbeanon-spontaneousprocess.