Definice
Když jsou v systému konstantní teplota, tlak, objem, stav hmoty, množství hmoty, fáze, různé energie atd., říkáme, že systém je ve stavu (stavu).
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.
Stav hmoty
Pevný
Kapalina
Plynný
Plazma
Boaikondenzovaná hmota
Fermionová kondenzovaná hmota
Neutronstát
Supravodivý stav
Superfluidstate
Supersolidstate
Spontánní a nespontánní proces
Thermodynamicsalsodividestheprocessintospontaneousandnon-spontaneousprocesses.Spontaneousprocessesareprocessesthatoccurnaturallyinnature,andgowiththeflow;non-spontaneousprocessesareprocessesthatdonotoccurnaturally.Examplesareasfollows:
Tepelné toky od vysoké teploty do nízké teploty
Voda teče z vysokých hor v rovinách
Vítr proudí od vysokého tlaku po nízký tlak
Proud teče z vysokého potenciálu (kladného) do nízkého potenciálu (záporný)
Hydroxideunderpressureiscombinedintowaterandheatflowsfromlowtemperaturetohightemperature(refrigerator)
Voda teče z roviny do hory (pumpa)
Airflowflowsfromlowpressuretohighpressure(compressor)
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Currentflowsfromlowelectricpotentialtohighelectricpotential(batterycharging)
Thedecompositionofwaterintohydrogenandoxygen(electrolysis)atnormaltemperatureandpressure
ThethermodynamicsprovethatinaclosedsystemIfaspontaneousprocessoccursintheprocess,thesystemmusthavethepossibilityofdoingusefulworktotheenvironment.Conversely,ifusefulworkmustbedonetoaclosedsystem,aprocesswilloccurinthesystem,andthisprocessmustbeanon-spontaneousprocess.