Umthetho Wokuqala Wezinto Ezisetshenziswa Yi-Thermodynamics
Inqubo ye-Thermodynamic
Ukushisa (Q) amandla asuka entweni eyodwa aye kwenye ngenxa yokwehluka kwezinga lokushisa. Ngokuphathelene nohlelo kanye nendawo ezungezile, ukushisa kungathiwa amandla asuka ohlelweni aye endaweni ezungezile noma amandla asuka endaweni ezungezile aye ohlelweni ngenxa yokwehluka kwezinga lokushisa. Uma izinga lokushisa lohlelo liphakeme kunezinga lokushisa lokusingqongileyo, ukushisa kuzogeleza kusuka ohlelweni kuye endaweni ezungezile. Ngokuphambene nalokho, uma izinga lokushisa lokusingqongileyo liphakeme kunezinga lokushisa lohlelo, ukushisa kuzogeleza kusuka endaweni ezungezile kuye ohlelweni.
Uma Ukushisa (Q) kuhlobene nokudluliselwa kwamandla ngenxa yomehluko wokushisa, khona-ke Umsebenzi (W) uhlobene nokudluliselwa kwamandla okwenzeka ngezindlela zemishini. Isibonelo, uma uhlelo lusebenza endaweni ezungezile, khona-ke amandla azohamba ngokuzenzakalelayo esuka ohlelweni aye endaweni ezungezile. Ngokuphambene nalokho, uma indawo ezungezile isebenza ohlelweni, khona-ke amandla azohamba esuka endaweni ezungezile aye ohlelweni.
Isibonelo esilula sokudluliselwa kwamandla phakathi kwesistimu nendawo ezungezile okubandakanya ukushisa nomsebenzi umusi oshisayo ocindezela isembozo sebhodwe. Ukuba khona kokushisa kubangela ukuthi uhlelo (umusi) lucindezele isembozo sebhodwe (umusi uyasebenza endaweni ezungezile). Lesi yisibonelo esisodwa soshintsho esimweni sesistimu ngenxa yokudluliselwa kwamandla phakathi kwesistimu nendawo ezungezile. Kunezinye izibonelo eziningi. Izinguquko esimweni sesistimu ngenxa yokudluliselwa kwamandla phakathi kwesistimu nendawo ezungezile okubandakanya ukushisa nomsebenzi zibizwa ngokuthi izinqubo ze-thermodynamic.
Amandla Angaphakathi kanye noMthetho Wokuqala We-Thermodynamics
Amandla angaphakathi (U) esistimu yisamba sawo wonke amandla e-kinetic ama-molecule ohlelweni, kanye nesamba sawo wonke amandla angaba khona avela ekusebenzisaneni phakathi kwama-molecule ohlelweni. Silindele ukuthi uma ukushisa kugeleza kusuka endaweni ezungezile kuya ohlelweni (uhlelo luthola amandla), amandla angaphakathi esistimu ayanda… Ngokuphambene nalokho, uma uhlelo lusebenza endaweni ezungezile (uhlelo lukhipha amandla), amandla angaphakathi esistimu ayancipha.
Ngakho-ke, ngokusekelwe esimisweni sokulondolozwa kwamandla, kungaphethwa ngokuthi ushintsho lwamandla ohlelweni = Ukushisa okungeziwe ohlelweni (uhlelo luthola amandla) – Umsebenzi owenziwe uhlelo (uhlelo lukhipha amandla). Ngokwezibalo:
Lesi sibalo sisebenza ohlelweni oluvaliwe (Uhlelo oluvaliwe luhlelo oluvumela kuphela ukushintshaniswa kwamandla phakathi kohlelo nendawo ezungezile). Kuhlelo oluvaliwe oluhlukanisiwe, akukho mandla angena noma aphuma ohlelweni, ngakho-ke, ushintsho lwamandla angaphakathi = 0.
Lesi sibalo sisebenza nasezinhlelweni ezivulekile uma sicabangela izinguquko zamandla ohlelweni ngenxa yokwengezwa nokunciphisa inani lezinto (Uhlelo oluvulekile uhlelo oluvumela ukushintshaniswa kwezinto namandla phakathi kohlelo nendawo ezungezile). Umthetho wokuqala we-thermodynamics wakhiwa ngekhulu le-19, ngemva kokuba ukushisa kwaqondwa njengamandla adluliselwa ngenxa yokwehluka kwezinga lokushisa.
Amandla angaphakathi ayinani elichaza isimo esincane kakhulu sesistimu. Inani elichaza isimo esincane kakhulu sesistimu (amandla angaphakathi) alinakunqunywa ngqo. Lokho esikuhlaziya ku-First Law of Thermodynamics equation kungukushintsha kwamandla angaphakathi kuphela. Izinguquko emandleni angaphakathi zinganqunywa ngenxa yamandla angeziwe ohlelweni kanye namandla akhishwa yisistimu ngesimo sokushisa nomsebenzi. Ngokuphambene nalokho, amanani achaza izimo ezinkulu anganqunywa ngqo. Inani elichaza izimo ezinkulu kakhulu izinga lokushisa (T), ingcindezi (p), ivolumu (V), kanye nobunzima (m) noma inani lama-moles (n). Ukushisa nomsebenzi kuhileleke kuphela enkambisweni yokudluliselwa kwamandla phakathi kwesistimu nendawo ezungezile; akuzona amanani achaza isimo sesistimu.
Sayina imithetho yokushisa (Q) kanye nomsebenzi (W)
Imithetho yesibonakaliso sokushisa nomsebenzi iyahambisana noMthetho Wokuqala we-Thermodynamics. Ukushisa (Q) ku-equation engenhla kumelela ukushisa okwengezwe ohlelweni (u-Q ulungile), kanti umsebenzi (u-W) ku-equation engenhla umelela umsebenzi owenziwe uhlelo (u-W ulungile). Uma ukushisa kushiya uhlelo, khona-ke u-Q ulungile. Ngokuphambene nalokho, uma umsebenzi wenziwa ohlelweni, khona-ke u-W ulungile.
Isibonelo sombuzo 1:
Uma amaJoules angu-2000 okushisa engezwa ohlelweni, kuyilapho uhlelo lwenza amaJoules angu-1000 okusebenza, luyini ushintsho emandleni angaphakathi ohlelweni?
Ingxoxo
Uhlelo luthola ukushisa okwengeziwe (amandla) kwama-Joules angu-2000. Uhlelo luphinde lwenze umsebenzi (ukukhishwa kwamandla) kwama-Joules angu-1000. Ngakho-ke, ushintsho lwamandla ohlelweni = ama-Joules angu-1000.
Isibonelo sombuzo 2:
Uma amaJoules angu-2000 okushisa ephuma ohlelweni futhi uhlelo lwenza amaJoules angu-1000 okusebenza, luyini ushintsho emandleni angaphakathi ohlelweni?
Ingxoxo
Uma ukushisa kushiya uhlelo, kusho ukuthi u-Q unenani elibi.
AmaJoules angu-2000 okushisa ayaphuma ohlelweni (uhlelo lukhipha amandla). AmaJoules angu-1000 omsebenzi nawo aqediwe (uhlelo lukhipha amandla). Ngakho-ke, amandla ohlelweni ancipha ngo-3000 J.
Isibonelo sombuzo 3:
Uma amaJoules angu-2000 okushisa engezwa ohlelweni futhi kwenziwa amaJoules angu-1000 omsebenzi ohlelweni, luyini ushintsho emandleni angaphakathi ohlelweni?
Ingxoxo
Uma umsebenzi wenziwa ohlelweni, khona-ke u-W u-negative.
Uhlelo luthola ukushisa okwengeziwe (uhlelo luthola amandla) kwamaJoules angu-2000 futhi kwenziwa umsebenzi ohlelweni (uhlelo luthola amandla) lwamaJoules angu-1000. Ngakho-ke, amandla ohlelweni anda ngamaJoules angu-3000.
Okokuqala , iningi lezinhlelo esizihlaziya ngokwemfundiso kulesi sihloko amagesi. Sisebenzisa amagesi ngoba izakhiwo zawo ezinkulu (izinga lokushisa, ingcindezi, kanye nomthamo) kulula ukuzinquma. Ekuhlaziyeni amagesi, sisawabheka njengamagesi afanele. Lokhu kumane nje ukwenza lula ukuhlaziya. Asisebenzisi amagesi angempela ngoba, lapho kucindezela kakhulu ngokwanele, amagesi angempela avame ukuziphatha ngendlela ephambene.
Okwesibili , uma uhlelo esiluhlaziyayo luyigesi efanelekile, khona-ke amandla angaphakathi angabalwa kusetshenziswa i-equation echaza ubudlelwano phakathi kwamandla angaphakathi egesi efanelekile kanye nokushisa kwegesi efanelekile: U = 3/2 nRT (i-equation yamandla angaphakathi yegesi efanelekile ye-monatomic).
Umsebenzi owenziwe uhlelo ngesikhathi sokushintsha kwevolumu
Ngaphambi kokuqhubeka, ake siqale sicabangele umsebenzi owenziwa uhlelo ezindaweni ezizungezile. Ukuze ubale inani lomsebenzi (W) owenziwa uhlelo, cabanga ngegesi efanelekile esitsheni esivalwe yi-piston. I-piston ingahanjiswa phezulu naphansi. Lesi sibalo senziwe lula sibe yizilinganiso ezimbili. Cabanga ngaso ngezilinganiso ezintathu. Ivolumu = ubude x ububanzi x ukuphakama.
Igesi elifanele limelelwa amaphuzu atholakala ngaphakathi kwesitsha. Isisekelo sesitsha sithinta into eshisa kakhulu (efana namanzi asebhodweni ashiswa phezu kwelangabi). Into eshisa kakhulu ayifakiwe esithombeni, cabanga nje engqondweni yakho 😉 Igesi elifanele esitsheni uhlelo, kanti ezinye izinto ezingaphandle kwesitsha, okuhlanganisa nento eshisa kakhulu ethinta isisekelo sesitsha, yimvelo. Ngenxa yokuthi izinga lokushisa elizungezile liphakeme kunezinga lokushisa lesistimu, ukushisa ngokwemvelo kugeleza kusuka endaweni ezungezile kuya ohlelweni. Ukwengezwa kwamandla avela endaweni ezungezile kubangela ukuthi amandla angaphakathi esistimu (igesi elifanele) akhuphuke. Amandla angaphakathi egesi elifanele alingana ngqo nezinga lokushisa (U = 3/2 nRT), ngakho-ke lapho amandla angaphakathi egesi elifanele enyuka, izinga lokushisa legesi elifanele nalo liyakhula. Ukwanda kwezinga lokushisa legesi elifanele kubangela ukuthi igesi elifanele likhule futhi licindezele i-piston ibanga s. Lapho ucindezela i-piston ibanga s, uhlelo (igesi elifanele) lusebenza endaweni ezungezile (umoya wangaphandle).
Ekuqaleni, ingcindezi yesistimu iphezulu (P1) kanti ivolumu yesistimu iphansi (V1). Ingcindezi ilingana ngokuphambene nevolumu. Ngemva kokushisa okugeleza kusuka endaweni ezungezile kuya ohlelweni futhi uhlelo lusebenza endaweni ezungezile, ivolumu yesistimu iyanda (V2) kanti ingcindezi yesistimu iyancipha (P2).
Inani lomsebenzi owenziwe uhlelo kule nqubo engenhla yileli:
Umsebenzi (W) = Amandla okusunduza (F) x ukufuduka (s). Njengoba amandla okusunduza (F) = ingcindezi (P) x indawo engaphezulu (A) yepiston, i-Work equation ingabhalwa kanje:
W = Fs ‐‐‐‐‐ F = PA
W = PAs ‐‐‐‐‐ As = V
W = i-PV
Kubalulekile ukuqaphela ukuthi umsebenzi owenziwa uhlelo lwenziwa ngesikhathi sokushintsha kwevolumu. Ngakho-ke, umsebenzi ophelele owenziwe uhlelo ungatholakala ngokuphindaphinda ushintsho ekucindezelweni ngokushintsha kwevolumu. Ngokwezibalo:
W = (ukucindezela kokugcina – ukucindezela kokuqala) (umthamo wokugcina – uvolumu wokuqala)
W = (P 2 ‐ P 1 )(V 2 ‐ V 1 )
Okokuqala , ushintsho kuvolumu yesistimu enqubweni engenhla lungatholakala kalula. Amavolumu okuqala nawokugcina esistimu angatholakala ngokubala ivolumu yesitsha. Ngakho-ke, ukuze sibale inani lomsebenzi (W) owenziwe yisistimu, sidinga ukwazi ukuthi ingcindezi ishintsha kanjani phakathi nenqubo.
Uma ingcindezi (p) yesistimu ishintsha ngokungajwayelekile njengoba ivolumu (V) ishintsha, khona-ke inani lomsebenzi owenziwe yisistimu lingabalwa kusetshenziswa i-calculus. Uma ungajwayelene ne-calculus, kunezinye izindlela ongazisebenzisa. Okokuqala, ake sidwebe igrafu ekhombisa ubudlelwano phakathi kwengcindezi nevolumu. Inani lomsebenzi owenziwe yisistimu = indawo enombala ngaphansi kwejika le-p-V.
Igrafu yokucindezela vs. ivolumu yezinguquko zokucindezela ezenzeka ngokungajwayelekile.
Ekuqaleni, ingcindezi yesistimu = p 1 (ingcindezi ephezulu) kanye nevolumu yesistimu = V 1 (ivolumu ephansi). Ngemva kokuba uhlelo lusebenze endaweni ezungezile, ingcindezi yesistimu ishintsha iye ku-p 2 (ingcindezi ephansi) kanye nevolumu yesistimu ishintsha iye ku-V 2 (ivolumu ephezulu). Inani lomsebenzi (W) owenziwa uhlelo = indawo enomthunzi. Ukuma kwejika kugobile ngoba ingcindezi yesistimu (igesi efanele) ishintsha ngokungajwayelekile ngesikhathi senqubo.
Uma ingcindezi (p) yesistimu ihlala ingaguquki njengoba ivolumu (V) ishintsha, khona-ke inani lomsebenzi owenziwe yisistimu lingabalwa kalula. Inani lomsebenzi owenziwe yisistimu lingabalwa kusetshenziswa i-equation noma lingatholakala endaweni enomthunzi ngaphansi kwejika le-P-V. Kulesi simo, i-equation yomsebenzi engenhla ingashintshwa kanje:
W = (P 2 ‐ P 1 )(V 2 ‐ V 1 )
Njengoba ingcindezi (p) ihlala ingaguquki, khona-ke u-P 2 = P 1 = P
W = P (V 2 - V 1 )
Igrafu yokucindezela vs ivolumu yenqubo lapho ingcindezi ihlala ingaguquki, okungukuthi, ayishintshi:
Ekuqaleni ivolumu yesistimu = V1 (ivolumu encane). Ngemva kokuba uhlelo lusebenze endaweni ezungezile, ivolumu yesistimu ishintsha ibe yi-V2 (umthamo omkhulu). Ukucindezela kohlelo kuhlala kungaguquki, okusho ukuthi akushintshi. Inani lomsebenzi (W) owenziwa uhlelo = indawo enomthunzi.
Okwesibili, uhlelo lusebenza ezindaweni ezizungezile uma ivolumu yesistimu ikhuphuka. Ngokuphambene nalokho, izindawo ezizungezile zisebenza ohlelweni uma ivolumu yesistimu incipha. Uma ivolumu yesistimu ingashintshi ngesikhathi senqubo, uhlelo alukwazi ukusebenza ezindaweni ezizungezile, futhi izindawo ezizungezile azikwazi ukusebenza ohlelweni. Kulokhu, umsebenzi (W) = 0.
