Isimiso sika-Le Chatelier: ukubikezela ukuthi ukulingana kusabela kanjani ekushintsheni

I-stress ishintsha u-Q noma u-K, futhi isistimu ibuyisela ukulingana

Ekulinganeni i-reaction quotient Q ilingana nokungaguquki kokulingana K. Isiphazamiso, esivame ukubizwa ngokuthi i-stress, siphula lokho kulingana ngenye yezindlela ezimbili. Ukwengeza noma ukususa uhlobo, noma ukushintsha ivolumu yengxube yegesi, kushintsha u-Q kanti u-K uhlala efana. Ukushintsha izinga lokushisa kushintsha u-K uqobo. Noma ngabe kunjani, isistimu bese isabela kuze kube yilapho u-Q elingana no-K futhi.

Uma u-Q manje emncane kuno-K, ukusabela kuya phambili, kubheke emikhiqizweni. Uma u-Q manje emkhulu kuno-K, kuya emuva. Ukucabanga ngale ndlela kuthembeke kakhulu kunezisho ezibanjwe ngekhanda, ngoba kuphinde kukutshele lapho kungekho shintsho nhlobo.

Igama elithi ngokwengxenye libalulekile. Isistimu ayilokothi iluhlehlise ngokuphelele ushintsho. Uma wengeza isisabelo, ukugxila kwaso ekulinganeni okusha kusephakeme kunalokho obekuyikho ngaphambi kokuthi usengeze.

Ukwengeza noma ukususa uhlobo

Ukwengeza isisabelo noma ukususa umkhiqizo kwehlisa u-Q angaphansi kuka-K, ngakho ukusabela kushintshela emikhiqizweni. Ukwengeza umkhiqizo noma ukususa isisabelo kukhuphula u-Q angaphezu kuka-K, ngakho ukusabela kushintshela ezisabelweni. Izinqubo zezimboni nezaselabhorethri zisebenzisa lokhu njalo. Ukukhipha umkhiqizo oguquka kalula ube umhwamuko nge-distillation, ukuvumela igesi iphunyuke, noma ukwenza umkhiqizo ube yi-precipitate kugcina u-Q engaphansi kuka-K futhi kuqhubela ukusabela phambili kakhulu kunalokho u-K wako yedwa obekungakuvumela.

Ukwengeza okwengeziwe kwento eqinile ehlanzekile noma uketshezi oluhlanzekile akukushintshi ukulingana. Lezo zinto azibonakali ku-Q, ngakho u-Q akashintshi. Ukwengeza i-CaCO₃(s) eyengeziwe esitsheni esivaliwe esekulinganeni ne-CaO(s) ne-CO₂(g) kushiya ingcindezi ye-CO₂ ingashintshile.

Isibonelo esisebenzile: i-hydrogen eyengeziwe ekulinganeni kwe-hydrogen iodide

Isigaba 13.3 se-OpenStax sinikeza u-Kc = 50.0 ku-400 °C ku-H₂(g) + I₂(g) ⇌ 2 HI(g). Ake sithi ingxube yokulingana kulelo zinga lokushisa ino-[H₂] = [I₂] = 0.0150 mol/L. Bese [HI] = √(50.0 × 0.0150 × 0.0150) = 0.106 mol/L.

Manje kujovwa i-H₂ ukuze u-[H₂] agxumele ku-0.0450 mol/L ngaphambi kokuthi kusabele lutho. Q = (0.106)² / (0.0450 × 0.0150) = 16.7. Lokho kungaphansi kuka-50.0, ngakho ukusabela kushintshela phambili futhi kusebenzise enye ye-H₂ eyengeziwe.

Ukuthola ukuthi kushintsha kangakanani, vumela u-x mol/L we-H₂ asabele. Bese [H₂] = 0.0450 − x, [I₂] = 0.0150 − x no-[HI] = 0.106 + 2x. Ukubeka (0.106 + 2x)² / [(0.0450 − x)(0.0150 − x)] = 50.0 nokuxazulula i-quadratic, ugcina amanani aphakathi angayisiwe, kunikeza x = 0.00728. I-root enengqondo ngokwe-physics yileyo encane kuno-0.0150, ngoba i-I₂ ayikwazi ukwehla ngaphansi kwe-zero. Ukulingana okusha kuno-[H₂] = 0.0377, [I₂] = 0.00772 no-[HI] = 0.121 mol/L.

Funda umphumela uwuqhathanisa nesimiso. Isistimu isebenzise cishe ingxenye yesine ye-hydrogen eyengeziwe, ngakho u-[H₂] waphetha ku-0.0377 mol/L, esengaphezulu kakhulu kuka-0.0150 wokuqala. Ngaleso sikhathi cishe uhhafu we-iodine waguqulwa waba yi-HI. Ukwengeza isisabelo esishibhile ukuze kusetshenziswe esibizayo kuyindlela ejwayelekile yokukhulisa isivuno.

Ukucindezela noma ukunweba ingxube yegesi

Ukwehlisa ivolumu yengxube yegesi kukhuphula konke ukugxila ngesici esifanayo. Ukuthi lokho kuyamshintsha yini u-Q kuncike ku-Δn, ama-mole emikhiqizo yegesi ukususa ama-mole ezisabelo zegesi. Uma u-Δn emubi, ukucindezela kwehlisa u-Q futhi ukusabela kushintshela ohlangothini olunamamolekyuli egesi ambalwa. Uma u-Δn emuhle, ukucindezela kukhuphula u-Q futhi ukusabela kushintshela ezisabelweni, okubuye kube wuhlangothi olunamamolekyuli egesi ambalwa. Uma u-Δn eyi-zero, njengaku-H₂ + I₂ ⇌ 2 HI, ukucindezela akumshintshi u-Q futhi akukho shintsho.

Ukukhuphula ingcindezi iyonke ngokwengeza igesi engasabeli efana ne-argon ngevolumu engaguquki akushintshi lutho. Izingcindezi ezingxenye nokugxila kwamagesi asabelayo kuhlala kufana, ngakho u-Q uhlala elingana no-K. Ukwengeza igesi engasabeli ngengcindezi engaguquki kwehlukile: isitsha kufanele sinwebeke, okunomphumela ofanayo nokukhulisa ivolumu.

Isibonelo esisebenzile: ukwehlisela ivolumu yengxube ye-NO₂–N₂O₄ engxenyeni

Ku-N₂O₄(g) ⇌ 2 NO₂(g) ku-25 °C, isigaba 13.2 se-OpenStax sichaza ingxube yokulingana eno-[N₂O₄] = 0.042 mol/L no-[NO₂] = 0.016 mol/L. Lokhu kunikeza Kc = (0.016)²/0.042 = 6.1 × 10⁻³.

Yehlisela ivolumu engxenyeni ezingeni lokushisa elingaguquki. Kokubili ukugxila kuyaphindeka kabili, kube ngu-[N₂O₄] = 0.084 no-[NO₂] = 0.032 mol/L. Q = (0.032)²/0.084 = 1.22 × 10⁻², okuphindwe kabili ncamashi u-Kc, ngoba ingxenye ye-NO₂ iyisikwele. Q > K, ngakho isistimu ishintshela ku-N₂O₄, uhlangothi olune-mole eyodwa yegesi esikhundleni sezimbili.

Vumela u-y mol/L we-N₂O₄ akheke. Ukuxazulula (0.032 − 2y)²/(0.084 + y) = 6.1 × 10⁻³ kunikeza y = 0.0044, ngakho ukulingana okusha kuno-[NO₂] = 0.023 mol/L no-[N₂O₄] = 0.088 mol/L, ezinombolweni ezibalulekile ezimbili njengedatha. I-NO₂ ensundu igxile kakhulu kunangaphambi kokucindezela (0.023 uma kuqhathaniswa no-0.016 mol/L), ngakho igesi ibukeka imnyama kakhulu, kodwa ingxenye encane ye-nitrogen manje iku-NO₂: amaphesenti angu-12 uma kuqhathaniswa nangu-16 ngaphambili.

Izinga lokushisa lishintsha u-K uqobo

Izinga lokushisa wukuphela koshintsho oluvamile oluguqula inani lika-K. Ekusabeleni kwe-endothermic (ΔH > 0), u-K uyakhula njengoba izinga lokushisa likhuphuka, ngakho ukufudumeza kushintshela ukulingana emikhiqizweni. Ekusabeleni kwe-exothermic (ΔH < 0), u-K uyehla njengoba izinga lokushisa likhuphuka, ngakho ukufudumeza kukushintshela ezisabelweni. Indlela ewusizo yokukhumbula lokhu ukuthatha ukushisa njengesisabelo ekusabeleni kwe-endothermic nanjengomkhiqizo ekusabeleni kwe-exothermic.

Isigaba 13.3 se-OpenStax sinikeza u-ΔH = +57.20 kJ ku-N₂O₄(g) ⇌ 2 NO₂(g), ngakho ukufudumeza ingxube kuyenza ibe nsundu kakhulu. Ubukhulu boshintsho bungalinganiselwa ngesibalo se-van 't Hoff, ln(K₂/K₁) = −(ΔH°/R)(1/T₂ − 1/T₁). Silandela ku-ΔG° = −RT ln K naku-ΔG° = ΔH° − TΔS° uma u-ΔH° no-ΔS° behlala cishe bengaguquki.

Isibonelo esisebenzile. Kusuka ku-25 °C (298.15 K) kuya ku-50 °C (323.15 K), ln(K₂/K₁) = −(57 200 J/mol ÷ 8.314 J mol⁻¹ K⁻¹)(1/323.15 − 1/298.15) = 1.785, ngakho K₂/K₁ = 6.0. Uqala ku-Kp = Kc × RT = (6.1 × 10⁻³)(0.08206 × 298.15) = 0.15 ku-25 °C (Δn = 1, izingcindezi zingu-atm), u-Kp ku-50 °C ucishe abe ngu-0.9. Ukukhuphuka kwamadigri angu-25 kukhulisa okungaguquki kokulingana cishe ngokuphindwe kasithupha.

I-catalyst ayikushintshi ukulingana. Yehlisa amandla e-activation okusabela okuya phambili nokuphambene ngokulinganayo, ngakho ukulingana kufinyelelwa ngokushesha, kodwa u-K nokwakheka kokulingana akushintshi.

I-ammonia ye-Haber–Bosch: ukulinganisa isivuno nesivinini

Ukwakhiwa kwe-ammonia ezimbonini, N₂(g) + 3 H₂(g) ⇌ 2 NH₃(g), kukhombisa ukuthi isimiso siqondisa kanjani izinqumo zangempela. Isigaba 13.3 se-OpenStax sinikeza u-ΔH = −92.2 kJ. Ukusabela kuyi-exothermic, ngakho amazinga okushisa aphansi anikeza u-K omkhulu ne-ammonia eningi ekulinganeni. Ama-mole amane egesi aba mabili, ngakho ingcindezi ephezulu nayo ithanda i-ammonia.

Ubunzima busesivinini. Ezingeni lokushisa eliphansi ukusabela kuhamba kancane kakhulu ukuthi kube wusizo. I-OpenStax ichaza ukuvumelana: izingcindezi ezicishe zibe ngu-150 kuya ku-250 atm, amazinga okushisa angu-400 kuya ku-500 °C ne-catalyst ukugcina izinga lisebenziseka, nokususwa okuqhubekayo kwe-ammonia engxubeni ukuze u-Q ahlale engaphansi kuka-K. Izinga lokushisa likhethelwa isivinini, ngentengo ka-K omncane, futhi ezinye izimo zibuyisa isivuno esiningi ngangokunokwenzeka.

Ukubikezela kuka-Le Chatelier okuhamba kabi

Lapho ukubikezela kuzwakala kungaqinisekile, bhala u-Q, shintsha inani okukhulunywa ngalo, bese uqhathanisa u-Q omusha no-K. Lokho kuhlola kuxazulula cishe zonke izimo ezingezansi.

• Ukuthi u-K uyashintsha lapho ukugxila noma ivolumu kushintsha. Izinga lokushisa kuphela elishintsha u-K.
• Ukubikezela ushintsho ngemva kokucindezela ukusabela okuno-Δn = 0, njengo-H₂ + I₂ ⇌ 2 HI.
• Ukubikezela ushintsho ngemva kokwengeza igesi engasabeli ngevolumu engaguquki.
• Ukubikezela ushintsho ngemva kokwengeza okwengeziwe kwento eqinile ehlanzekile noma uketshezi.
• Ukuthi i-catalyst ikhulisa isivuno sokulingana. Isheshisa nje ukusondela ekulinganeni.
• Ukucabanga ukuthi isistimu ikhansela ushintsho ngokuphelele. Isisabelo esengeziwe siphetha singaphezu kokugxila kwaso kokuqala.
• Ukubala wonke ama-mole, hhayi ama-mole egesi kuphela, lapho unquma ukuthi ushintsho lwengcindezi lusebenza kanjani.