Ukuqonda i-Enthalpy kanye ne-Entropy
Kumakhemikhali kanye ne-thermodynamics, i-enthalpy kanye ne-entropy yimibono emibili eyisisekelo ebalulekile ekuqondeni ukuthi izinhlelo zamandla zisebenza kanjani. Zidlala indima ebalulekile ekusabeleni okuhlukahlukene kwamakhemikhali, izinqubo zomzimba, ngisho nobuchwepheshe bamandla avuselelekayo. Lesi sihloko sizochaza ngokujulile i-enthalpy kanye ne-entropy nokuthi zixhumana kanjani ezimweni ezahlukene.
Ukuqonda i-Enthalpy
Incazelo ye-Enthalpy
I-Enthalpy iyisici se-thermodynamic esisetshenziselwa ukukala inani eliphelele lamandla ohlelweni, okuhlanganisa amandla angaphakathi namandla aqukethwe ngesimo sokucindezela kanye nomthamo. I-Enthalpy ivame ukufanekiswa ngohlamvu \( H \) futhi ilinganiswa ngamayunithi ama-joules (J) ku-International System (SI).
Ngokwezibalo, i-enthalpy ingachazwa ngokuthi:
\[ H = U + PV \]
lapho \( U \) kungamandla angaphakathi esistimu, \( P \) kungukucindezela, kanye \( V \) kungumthamo.
Umsebenzi we-Enthalpy ekuphenduleni kwamakhemikhali
Uma kukhulunywa ngokusabela kwamakhemikhali, ushintsho lwe-enthalpy (\( \Delta H \)) lubonisa ukuthi ukusabela kuyi-exothermic (ukukhulula amandla ngesimo sokushisa) noma i-endothermic (amandla amuncayo). Uma \( \Delta H \) ingalungile, ukusabela kuyi-exothermic; uma \( \Delta H \) ilungile, ukusabela kuyi-endothermic.
Isibonelo, ekushisweni kukaphethiloli njenge-methane (\( CH_4 \)):
\[ CH_4 + 2O_2 \umcibisholo wakwesokudla CO_2 + 2H_2O + amandla \]
Lokhu kusabela kukhulula amandla, ngakho-ke kune-negative \( \Delta H \).
Ukulinganisa i-Enthalpy
Kubalulekile ukukhumbula ukuthi asikwazi ukulinganisa i-enthalpy ephelele yesistimu, kodwa singalinganisa ushintsho ku-enthalpy (\( \Delta H \)). Ekuhlolweni kwelabhorethri, izinguquko ze-enthalpy zivame ukulinganiswa kusetshenziswa i-calorimetry, okungukuthi, ngokulinganisa inani lokushisa okukhishwe noma okumuncwa ngesikhathi sokusabela.
Ukuqonda i-Entropy
Incazelo ye-Entropy
I-Entropy iyisilinganiso sokuphazamiseka noma isiphithiphithi ohlelweni. Ku-thermodynamics, i-entropy ivame ukufanekiselwa uhlamvu \(S \) futhi ilinganiswa ngamayunithi ama-joules nge-kelvin (J/K) ku-International System (SI). Umqondo we-entropy wethulwa okokuqala yisazi sefiziksi saseJalimane uRudolf Clausius ngekhulu le-19.
I-Entropy ifanekiselwa yi-equation:
\[ \Delta S = \frac{q_{rev}}{T} \]
lapho \( \Delta S \) kungushintsho ku-entropy, \( q_{rev} \) kungukushisa okudluliselwe enqubweni eguqukayo, kanye \( T \) kungukushisa okuphelele.
Isimiso se-Entropy ku-Thermodynamics
Esinye sezimiso eziyisisekelo ze-thermodynamics ukuthi indawo yonke ithambekele ekwandiseni i-entropy. Ngamanye amazwi, izinqubo zemvelo zihlala zihamba ziye ekwandiseni isiphithiphithi noma ukuphazamiseka. Lesi simiso saziwa ngokuthi uMthetho Wesibili we-Thermodynamics.
I-Entropy Ekuphenduleni Kwamakhemikhali
Uma kukhulunywa ngokusabela kwamakhemikhali, ushintsho ku-entropy (\( \Delta S \)) lusitshela ukuthi imikhiqizo yokusabela ihlelekile noma ayihlelekile yini uma kuqhathaniswa nama-reactants. Uma \( \Delta S \) ilungile, imikhiqizo ihlelekile kakhulu; uma \( \Delta S \) ingalungile, imikhiqizo ihlelekile kakhulu.
Isibonelo esivamile esisetshenziswa ukuchaza lo mqondo ukuxubana kwamagesi amabili. Uma amagesi amabili exutshwa, i-entropy iyonke yesistimu iyanda ngoba ama-molecule egesi ahlakazeka kakhulu futhi aphazamiseke.
Ukusebenzisana Phakathi Kwe-Enthalpy Ne-Entropy: Umsebenzi we-Gibbs
Ukuze siqonde kabanzi ukuthi i-enthalpy kanye ne-entropy ndawonye zithinta kanjani ukusabela kwamakhemikhali kanye nezinqubo ze-thermodynamic, kumelwe sibheke umsebenzi we-Gibbs noma amandla amahhala e-Gibbs, achazwa yi-\( G \).
Amandla amahhala e-Gibbs achazwa kanje:
\[ G = H – TS \]
lapho \( H \) kuyi-enthalpy, \( T \) kuyizinga lokushisa eliphelele, kanye \( S \) kuyi-entropy.
Ushintsho lwamandla amahhala e-Gibbs (\( \Delta G \)) lunikeza inkomba yokuzenzakalela kwenqubo noma ukusabela. Uma \( \Delta G \) ingalungile, inqubo izokwenzeka ngokuzenzekelayo. Uma \( \Delta G \) ilungile, inqubo ngeke yenzeke ngokuzenzekelayo. Uma \( \Delta G \) ingu-zero, uhlelo lusesilinganisweni.
Ikesi lesampula
Ake sicabangele inqubo yokuncibilikisa iqhwa libe ngamanzi ku-0°C (273.15 K):
\[ H_2O_{(s)} \umcibisholo ongakwesokudla H_2O_{(l)} \]
Kule nqubo, kukhona ushintsho lwe-enthalpy (\( \Delta H \)) ngoba kudinga amandla ukuphula izibopho eqhweni. Kukhona futhi ushintsho lwe-entropy (\( \Delta S \)) ngoba amanzi acwebile aphazamisekile kakhulu kuneqhwa.
Ushintsho lwe-enthalpy lokuncibilikisa iqhwa lucishe lube ngu-+6.01 kJ/mol, kanti ushintsho lwe-entropy lucishe lube ngu-+22.0 J/K·mol. Singabala \( \Delta G \) ukuthola ukuzenzela kwenqubo:
\[ \Delta G = \Delta H – T \Delta S \]
Ku-0°C (273.15 K):
\[ \Delta G = 6010 – 273.15 \izikhathi ezingu-22 \]
\[ \Delta G = 6010 – 6009.3 \cishe kube ngu-0.7 \umbhalo{ J/mol} \]
Njengoba i-\( \Delta G \) iseduze no-zero, lokhu kubonisa ukuthi inqubo yokuncibilikisa iqhwa ku-0°C ilingana.
Ukufaneleka Ekuphileni Kwansuku Zonke
Ukuqonda i-enthalpy kanye ne-entropy kubalulekile ezicini ezahlukene zokuphila komuntu, kusukela kubuchwepheshe kuya kwisayensi yezempilo. Isibonelo, embonini yokudla, izinqubo zokupheka kanye nokugcina zivame ukuhilela ukulawula izinguquko ze-enthalpy kanye ne-entropy ukuze kugcinwe ikhwalithi yokudla. Kubuchwepheshe bamandla avuselelekayo, njengamaseli elanga namabhethri, ukuhlaziywa kwe-thermodynamic kusiza ukuthuthukisa ukusebenza kahle kanye nokuthembeka.
Ngaphezu kwalokho, esimweni semvelo, izimiso ze-enthalpy kanye ne-entropy zingasetshenziswa ukuqonda izinqubo zemvelo ezifana nomjikelezo wamanzi, i-photosynthesis, kanye nokushintsha kwesimo sezulu. Lolu lwazi luphinde lusize ekwakheni ubuchwepheshe namasu okunciphisa imiphumela emibi kwezemvelo.
Isiphetho
I-Enthalpy kanye ne-entropy yimibono emibili ehlobene ye-thermodynamic ebalulekile ekuqondeni izinqubo ezahlukahlukene zamakhemikhali nezomzimba. I-Enthalpy ihlobene namandla aphelele esistimu, kuyilapho i-entropy ikhombisa izinga lokuphazamiseka noma ukuphazamiseka. Ukusebenzisana phakathi kwe-enthalpy kanye ne-entropy, njengoba kulinganiswa umsebenzi we-Gibbs, kunikeza ukuqonda okubalulekile ngokuzenzekela kanye nokulingana kwezinqubo ze-thermodynamic. Ukuqonda le mibono akubalulekile nje kuphela embonweni kodwa futhi kunezindlela ezisebenzayo kwezobuchwepheshe, embonini, nasempilweni yansuku zonke.
