Inqubo ye-isothermal wuhlobo loguquko lwe-thermodynamic lapho izinga lokushisa lesistimu lihlala lingashintshi kuyo yonke inqubo. Lokhu kusho ukuthi amandla angaphakathi esistimu ahlala engashintshi, kuyilapho ukushisa nomsebenzi okushintshaniswa nendawo ezungezile kuyalingana ukuze kugcinwe izinga lokushisa elingashintshi.
Isibonelo esivamile senqubo ye-isothermal ukunwetshwa kwegesi kusilinda ngepiston, okugcina izinga lokushisa eliqhubekayo kuyo yonke inqubo. Esinye isibonelo kungaba ukucindezelwa kwe-isothermal kwegesi emjikelezweni wesiqandisi.
Ukuzivocavoca okubandakanya izinqubo ze-isothermal kungase kuhlanganise ukubala umsebenzi owenziwe noma ukushintshaniswa kokushisa ngesikhathi sokuguqulwa, kusetshenziswa izibalo ezifanele ze-thermodynamic. Kubalulekile ukukhumbula ukuthi, ohlelweni lwe-isothermal, ukuguqulwa kwamandla angaphakathi kunguziro, okwenza izibalo zibe lula.
Ukuguqulwa kwe-Isothermal: umqondo kanye nezibonelo ezingokoqobo zokusetshenziswa kwawo ku-thermodynamics.
Inqubo ye-isothermal yileyo lapho izinga lokushisa lesistimu lihlala lingashintshi kulo lonke uguquko. Lokhu kusho ukuthi amandla ashisayo ashintshaniswa nendawo ezungezile ngendlela yokuthi izinga lokushisa lihlale lingashintshile. Lolu hlobo lokuguqulwa luvamile ezinhlelweni ze-thermodynamic, lapho izinga lokushisa lilawulwa ukuze kuqinisekiswe ukuzinza kwenqubo.
Isibonelo esisebenzayo senqubo ye-isothermal ukucindezelwa kwegesi ekahle kusilinda ngepiston ehambayo. Uma igesi icindezelwa kancane futhi ngendlela elawulwayo, izinga lokushisa lesistimu lihlala lingashintshi kuyo yonke inqubo. Lokhu kwenzeka ngenxa yokuthi amandla ashisayo akhiqizwa ukucindezela ahlakazeka endaweni ezungezile, okugcina izinga lokushisa lesistimu lingashintshi.
Esinye isibonelo senqubo ye-isothermal ukunwetshwa kwegesi enjinini yokushisa. Kulokhu, izinga lokushisa lesistimu lilawulwa ukuze kuqinisekiswe ukuthi ukwanda kwegesi kwenzeka ngokuphumelelayo, ngaphandle kokushintsha kwezinga lokushisa okungazelelwe okungathinta ukusebenza kwenjini.
Lolu hlobo lwenqubo luvamile ezinhlelweni ze-thermodynamic, lapho izinga lokushisa lilawulwa ukuze kuqinisekiswe ukuzinza nokusebenza kahle kwenqubo.
Incazelo yenqubo ye-isothermal: ukuhlukahluka kwezinga lokushisa okungaguquki ohlelweni lwe-thermodynamic.
Inqubo ye-isothermal umqondo oyisisekelo ku-thermodynamics obhekisela ekushintsheni okungaguquki kwezinga lokushisa ohlelweni lwe-thermodynamic. Lokhu kusho ukuthi, kuyo yonke inqubo, izinga lokushisa lesistimu lihlala lifana, ngaphandle kokushintsha. Ngamanye amazwi, amandla ashisayo ashintshaniswa nendawo ezungezile ngendlela yokuthi izinga lokushisa lihlale lingashintshile.
Um isibonelo Isibonelo esivamile senqubo ye-isothermal ukunwetshwa kwegesi ekahle kusilinda ngepiston ye-adiabatic. Kulokhu, igesi yanda kancane, ukuze izinga lokushisa lesistimu lihlale lihlala njalo. Esinye isibonelo ukucindezelwa kwegesi ohlelweni oluvaliwe, lapho izinga lokushisa legesi lihlala lifana kuyo yonke inqubo.
Ukuze siqonde kangcono umqondo wenqubo ye-isothermal, singakwazi ukwenza izivivinyo elula. Isibonelo, singakwazi ukubala inani lokushisa elishintshiwe phakathi nenqubo ye-isothermal sisebenzisa i-equation Q = nRTln(Vf/Vi), lapho u-Q emele ukushisa okushintshiwe, n inani lendaba, R igesi engaguquki, T izinga lokushisa, futhi i-Vf ne-Vi amavolumu okugcina kanye nasekuqaleni, ngokulandelanayo.
Kubalulekile ukuqonda lo mqondo ukuze uhlaziye futhi uxazulule izinkinga ezihlobene ne-thermodynamics.
Umhlahlandlela wesinyathelo ngesinyathelo ekudaleni i-akhawunti ngenkathi ugcina izinga lokushisa elingashintshi.
Inqubo ye-isothermal wuhlobo loguquko lwe-thermodynamic lapho izinga lokushisa lesistimu lihlala lingashintshi kuyo yonke inqubo. Lokhu kusho ukuthi amandla angaphakathi esistimu ahlala efana, ngisho noma ukushisa kushintshaniswa nendawo ezungezile.
Ukuze udale i-akhawunti egcina izinga lokushisa elingashintshi, landela lezi zinyathelo:
Isinyathelo 1: Khetha isitsha esifanele ukugcina uhlelo futhi uqinisekise ukuthi izinga lokushisa ligcinwa ngokulinganayo.
Isinyathelo 2: Faka izinto ezidingekayo esitsheni, uqinisekise ukuthi izinga lokushisa lokuqala liyizinga lokushisa elifunayo lenqubo ye-isothermal.
Isinyathelo 3: Qiniseka ukuthi isiqukathi sivalwe ngokushisa kahle ukuze ugweme ukushintshaniswa kokushisa nendawo ezungezile.
Isinyathelo 4: Qaphela njalo izinga lokushisa lesistimu futhi wenze izinguquko njengoba kudingeka ukuze uligcine lingashintshi kuyo yonke inqubo.
Isibonelo esisebenzayo senqubo ye-isothermal ukunwetshwa kwegesi ekahle ku-piston evalwe nge-thermal. Ngesikhathi sokunwetshwa, izinga lokushisa legesi lihlala lihlala njalo, liqinisekisa ukuthi amandla angaphakathi esistimu awashintshi.
Ukuze uqinise umqondo, ungazama ukuxazulula umsebenzi olandelayo: imvukuzane eyodwa yegesi ekahle ithola ukukhuliswa kwe-isothermal kusuka ku-2 amalitha kuya ku-10 amalitha ekushiseni kuka-300 K. Yimuphi umsebenzi owenziwe igesi phakathi nenqubo?
Ngithemba ukuthi lesi sihloko sicacise ukuthi iyini inqubo ye-isothermal nokuthi ungayidala kanjani ngenkathi kugcinwa izinga lokushisa eliqhubekayo. Khumbula ukugcina izinga lokushisa lingaphansi kokulawula ukuze uqinisekise ukusebenza kahle kwenqubo.
Qonda incazelo yokusabela kwe-isothermal nezici zayo eziyinhloko zokushisa ezingaguquki.
Inqubo ye-isothermal yileyo lapho izinga lokushisa lihlala lingashintshi kukho konke ukusabela. Lokhu kusho ukuthi amandla okushisa ashintshiwe nendawo ezungezile alingana ncamashi namandla amuncwa noma akhishwe ngesikhathi sokusabela, okugcina izinga lokushisa lingashintshi. Lolu hlobo lwenqubo luvame kakhulu ezinhlelweni ze-thermodynamic, lapho izinga lokushisa liyipharamitha ebalulekile yokulawula.
Izici eziyinhloko zokusabela kwe-isothermal yilezi ukushisa okungaguquki kanye ukungabikho kokuhlukahluka kokushisa kuyo yonke inqubo. Lokhu kuvumela izibalo ze-thermodynamic ukuthi zisetshenziswe kalula, njengoba izinga lokushisa liyinani elaziwayo neliqhubekayo.
Isibonelo senqubo ye-isothermal ukunwetshwa kwegesi ekahle ngezinga lokushisa elingashintshi. Kulesi simo, izinga lokushisa legesi lihlala lihlala njalo kulo lonke inqubo yokwandisa, ukugcina amandla okushisa esistimu engashintshiwe.
Ukuze siwufanekise kangcono lo mqondo, singacabangela umsebenzi olula: cabanga ngesitsha esinegesi ekahle ezingeni lokushisa lokuqala elingu-300K. Uma le gesi inweba ngendlela ehlukile, igcina izinga lokushisa lingashintshi, lizoba yini izinga lokushisa lokugcina legesi ngemva kokunwetshwa? Impendulo iwukuthi izinga lokushisa lokugcina lizoba ngu-300K, ngoba inqubo ye-isothermal izinga lokushisa alishintshi.
Iyini inqubo ye-isothermal? (Izibonelo, izivivinyo)
A isothermal inqubo ye-isothermal noma inqubo ye-thermodynamic ebuyisela emuva lapho izinga lokushisa lihlala lingashintshile. Egesini, kunezimo lapho uguquko ohlelweni lungakhiqizi ukuhlukahluka kwezinga lokushisa, kodwa ngezici zomzimba.
Lezi zinguquko zibizwa ngokuthi izinguquko zesigaba, lapho into ishintsha isuka kokuqinile iye oketshezini, isuka oketshezini iye kugesi, noma ngokuphambene. Kulezi zimo, ama-molecule ento alungisa indawo yawo, engeza noma ekhipha amandla ashisayo.
Amandla ashisayo adingekayo ukuze uguquko lwesigaba lwenzeke entweni ibizwa ngokuthi ukushisa okucashile noma ukushisa kokuguqulwa.
Enye indlela yokwenza inqubo i-isothermal iwukubeka into ezoba uhlelo olucwaningwayo ixhumene ne-thermal reservoir yangaphandle, okungesinye isimiso esinamandla aphezulu e-caloric. Lokhu kubangela ukushintshana kokushisa okuhamba kancane kangangokuthi izinga lokushisa lihlala lingashintshi.
Lolu hlobo lwenqubo lwenzeka kaningi emvelweni. Ngokwesibonelo, kubantu, lapho izinga lokushisa lomzimba wethu likhuphuka noma lehla, sizizwa sigula, ngoba emizimbeni yethu, inqwaba yamakhemikhali asekela ukuphila kwenzeka lapho izinga lokushisa lihlala likhona. Lokhu kuyiqiniso ezilwaneni ezinegazi elifudumele ngokujwayelekile.
Ezinye izibonelo zihlanganisa iqhwa elincibilika ekushiseni kwentwasahlobo nama-ice cubes aqanda isiphuzo.
Izibonelo zezinqubo ze-isothermal
-I-metabolism yezilwane ezinegazi elifudumele yenziwa ngokushisa okungashintshi.
-Lapho amanzi ebila, kwenzeka ushintsho lwesigaba, ukusuka oketshezini kuya kugesi, futhi izinga lokushisa lihlala lingashintshile cishe ku-100ºC, njengoba ezinye izici zingathonya inani.
Ukuncibilika kweqhwa kungenye inqubo evamile ye-isothermal, njengoba kunjalo ngokufaka amanzi efrijini ukwenza ama-ice cubes.
- Izinjini zezimoto, iziqandisi, nezinye izinhlobo eziningi zemishini zisebenza kahle ngaphakathi kwebanga elithile lokushisa. Amadivayisi abizwa ama-thermostats zisetshenziselwa ukugcina lokushisa ezifanele. Izimiso eziningana zokusebenza zisetshenziswa ekwakhiweni kwayo.
Umjikelezo weCarnot
Injini yeCarnot ingumshini okahle okutholwa kuwo umsebenzi ngenxa yezinqubo ezibuyiseleka emuva ngokuphelele. Iwumshini okahle ngoba awucabangi izinqubo ezichitha amandla, njengokubonakala kwento eyenza umsebenzi, noma ukungqubuzana.
Umjikelezo weCarnot unezigaba ezine, ezimbili zazo ziyi-isothermal kanye nezinye ezimbili ze-adiabatic. Izigaba ze-isothermal ziwukucindezelwa nokwandiswa kwegesi ebhekele ukukhiqiza umsebenzi owusizo.
Injini yemoto isebenza ngezimiso ezifanayo. Ukunyakaza kwepiston ngaphakathi kwesilinda kudluliselwa kwezinye izingxenye zemoto, ikhiqize ukunyakaza. Ayiziphathi njengesistimu ekahle njengenjini yeCarnot, kodwa izimiso ze-thermodynamic zivamile.
Ukubalwa komsebenzi owenziwe ngenqubo ye-isothermal
Ukuze ubale umsebenzi owenziwe uhlelo lapho izinga lokushisa lihlala njalo, udinga ukusebenzisa umthetho wokuqala we-thermodynamics, othi:
ΔU = Q - W
Lena enye indlela yokuveza ukongiwa kwamandla ohlelweni, okwethulwa ngokusebenzisa ΔU noma ukushintsha amandla, Q njengoba ukushisa kunikezwa futhi ekugcineni, W , okuwumsebenzi owenziwa uhlelo okukhulunywa ngalo.
Ake sithi isistimu okukhulunywa ngayo iyigesi efanelekile equkethwe kusilinda piston esuka endaweni A , okusebenza lapho ivolumu yakho V izinguquko ze V 1 ukuze V 2 .
I-equation yegesi ekahle yombuso ngu I-PV = nRT , ehlobene nevolumu nokucindezela P kanye nezinga lokushisa T . Amanani ka-n kanye no-R angama-constants: n inombolo yama-moles wegesi futhi u-R yigesi engaguquki. Endabeni yenqubo ye-isothermal, umkhiqizo PV ihlala njalo.
Awu, umsebenzi owenziwe ubalwa ngokuhlanganisa umsebenzi omncane wokuhlukanisa, lapho amandla F ikhiqiza i-dx encane yokufuduka:
dW = Fdx = PAdx
Como I-Adx yikho kanye ukuhluka kwevolumu dV , bese:
dW = PoE
Ukuthola umsebenzi ophelele kunqubo ye-isothermal, isisho se-dW sihlanganisiwe:
Ingcindezi P kanye nevolumu V ahlelwe kumdwebo PV njengoba kuboniswe emfanekisweni nomsebenzi owenziwe ulingana nendawo engaphansi kwejika:
Como ΔU = 0, njengoba izinga lokushisa lihlala lingashintshile, kunqubo ye-isothermal, sina:
Q = W
– Isivivinyo 1
Isilinda esinepiston esinyakazayo siqukethe igesi ekahle engu-127°C. Uma i-piston ihanjiswa izikhathi eziyi-10 kumthamo wayo wokuqala, ukugcina izinga lokushisa lingashintshi, thola inani lemvukuzane yegesi equkethwe kusilinda uma umsebenzi owenziwe ngegesi ungu-38.180 J.
Ulwazi : R = 8,3 J / mol. K
Isixazululo
Isitatimende sithi izinga lokushisa lihlala lingashintshi, ngakho siphambi kwenqubo ye-isothermal. Ngomsebenzi owenziwe ngegesi, sinesibalo esithathwe ngaphambili:
127ºC = 127 + 273K = 400K
Xazulula okuthi n, inani lama-moles:
n = W / RT ln (V2 / V1) = -38 180 J / 8,3 J / mol K x 400 K x ln (V 2 / 10V 2 ) = 5 imvukuzane
Uphawu olubi lwalubekwe ngaphambi komsebenzi. Umfundi oqaphile kungenzeka ukuthi ubonile esigabeni esidlule ukuthi u-W uchazwe ngokuthi "umsebenzi owenziwe uhlelo" futhi unophawu +. Ngakho-ke, "umsebenzi owenziwe ohlelweni" uphethe uphawu olubi.
– Isivivinyo 2
Kunomoya kusilinda nepiston. Ekuqaleni, kukhona 0,4 m 3 wegesi ngaphansi kwengcindezi ye-100 kPa kanye nezinga lokushisa lika-80 ° C. Umoya ucindezelwa ku-0,1 m 3, ukuqinisekisa ukuthi izinga lokushisa ngaphakathi kwesilinda lihlala lingashintshi phakathi nenqubo.
Thola ukuthi ungakanani umsebenzi owenziwayo phakathi nale nqubo.
Isixazululo
Sisebenzisa i-equation emsebenzini otholwe ngaphambili, kodwa inani lama-moles alaziwa, elingabalwa nge-equation yegesi efanelekile:
80 º C = 80 + 273 K = 353 K.
P 1 V 1 = nRT → n = P 1 V 1 / RT = 100000 Pa x 0,4 m 3 / 8,3 J / mol. K x 353 K = 13,65 mol
W = nRT ln (V 2 /V 1 ) = 13,65 mol x 8,3 J / mol. K x 353 K x ln (0,1 / 0,4) = -55.442,26 J
Futhi, uphawu olubi lubonisa ukuthi umsebenzi wenziwa ohlelweni, okwenzeka njalo lapho igesi icindezelwa.
Izinkomba
- Bauer, W. 2011. I-Physics for Engineering and Science. Umqulu 1. McGraw Hill.
- Cengel, Y. 2012. Thermodynamics. 7 ma Uhlelo. UMcGraw Hill.
- U-Figueroa, D. (2005). Uchungechunge: I-Physics yeSayensi nobunjiniyela. Umqulu 4. Fluids kanye Thermodynamics. Ihlelwe nguDouglas Figueroa (USB).
- Knight, R. 2017. I-Physics yososayensi nonjiniyela: indlela yamasu.
- Serway, R., Vulle, C. 2011. Okuyisisekelo se-Physics. 9 na Khulisa Ukufunda.
- I-Wikipedia. Inqubo ye-Isothermal. Ithathwe ku: en.wikipedia.org.