Ukuvutha ukwakheka - Iyini?

Sikhuluma nabo ngezinto ukushisa kumiswa, kanye ukuchaza izimo ezazidinga ejwayelekile. Ukuze zilungisa lolu daba, ukuthola umehluko phakathi izinto ezilula futhi eziyinkimbinkimbi. Ukuhlanganisa welithi "ukushisa kumiswa", cabanga ethize chemical equation.

I enthalpy esezingeni kumiswa izinto

76 kJ energy olukhishwe ekusabeleni carbon nge hydrogen ukuxhumana. Kulokhu, lesi sibalo - umphumela ezishisayo of ukusabela zamakhemikhali. Kodwa lokhu ukushisa kumiswa methane molecule kusuka izinto ezilula. "Kungani?" - You buza. Lokhu kungenxa yokuthi yezingxenye kokuqala kukhona i-carbon ne-hydrogen. 76 kJ / Mol iyona energy ukuthi osokhemisi ngokuthi "ukushisa kumiswa".

idatha yespredishithi

Ngo thermochemistry khona amatafula eziningi, aqukethe nokuvutha kumiswa ahlukahlukene chemical kusuka izinto ezilula. Ngokwesibonelo, ukushisa kumiswa we ketshezi, ifomula zazo CO ₂ e isimo gaseous has a sibalo 393,5 kJ / Mol.

ukubaluleka esisebenzayo

Kungani amanani wedatha? Ukushisa kumiswa - value, esetshenziswa ngesikhathi sibalo umphumela ezishisayo kwanoma iyiphi inqubo yamakhemikhali. Ukuze ukuqhuba izibalo ezinjengalezi ezidinga ukusetshenziswa komthetho thermochemistry.

thermochemistry

Kuyinto emthethweni oyisisekelo uchaza izinqubo amandla ebonwe inkambo ukuphendula kwamakhemikhali. Phakathi nokuxhumana waphawula izinguquko qualitative ohlelweni ukusabela. Ezinye izinto zinyamalale, izingxenye ezintsha avele endaweni yawo. Le nqubo ibizwa ephelezelwa ushintsho amandla sangaphakathi sohlelo, sikhonjiswa ifomu yomsebenzi noma ukushisa. Umsebenzi, okuyinto lihlotshaniswa isandiso, ngokuba zamakhemikhali uyisihluthulelo aphansi. Ukushisa eyakhishwa ngo ukuguquka eyodwa ingxenye ku enye into kungaba ungowenani elikhulu.

Uma sicabanga ngezindlela ezihlukahlukene kugucuka, cishe yonke kukhona ukumuncwa noma ukudedela ethile ukushisa. thermochemistry - nesigaba okhethekile sidaliwe ukuze uthole incazelo izenzakalo.

Umthetho Hess sika

Ngenxa umthetho wokuqala wokushintsha kwamandla nokwakheka kwezinto, sekungenzeka ukuba sifeze ekubalweni umphumela ezishisayo kuncike nemibandela ukusabela zamakhemikhali. izibalo Ngokusekelwe umthetho main thermochemistry, okungukuthi umthetho Hess. Ake ekwakhiweni yayo: ezishisayo umphumela chemical ukuguqulwa ezihlobene imvelo, isimo sokuqala futhi yokugcina impahla, akahlotshaniswa nge indlela yokusebenza.

Yini elandelayo kusukela kule ekwenziweni? Endabeni umkhiqizo othize akudingeki sisetshenziswe kuphela komunye samuntu nokuxhumana, ukusabela kungenzeka kwenziwe ngezindlela ezihlukahlukene. Kunoma ikuphi, kungakhathaliseki ukuthi unikeza impahla oyifunayo, umphumela ezishisayo inqubo izohlala ukubaluleka zinjalo. Ukuze uchaze kubalulekile ukuba afingqe imiphumela ezishisayo kugucuka Lesisemkhatsini. Ngenxa yomthetho Hess sebekwazi afeze izibalo wathola imali imiphumela ezishisayo, akunakwenzeka ukuba sifeze ku Calorimeter. Ngokwesibonelo, ukubeka inani ukushisa kumiswa i-carbon monoxide izinto ibalwa ngumthetho Hess, kodwa nge nokucwaninga isimiso ukunquma ke ngeke aphumelele. Ngakho-ke kubalulekile ekhethekile amatafula thermochemical lapho amanani ezinombolo ohlwini izinto ezihlukahlukene njengoba kuchaziwe ngaphansi kwezimo ezijwayelekile

amaphuzu abalulekile ukubala

Njengoba sazi ukuthi ukushisa kumiswa - ukushisa wokusabela, kubaluleke oluthile isimo uquqaba ketshezi embuzweni. Ngokwesibonelo, lapho izilinganiso ukuthatha ubhekwa isimo ejwayelekile carbon-graphite, esikhundleni idayimane. Futhi acabangele ingcindezi kanye lokushisa, okungukuthi, izimo lapho ekuqaleni ukusabela izingxenye. Lezi lucobo bayakwazi ukuba nethonya ebalulekile indlela abasabela ngayo, luyanda noma kwanciphisa inani amandla. Ukuze wenze izibalo eziyisisekelo e thermochemistry wanquma ukusebenzisa izinkomba obuphathekayo ingcindezi kanye lokushisa.

izimo ejwayelekile

Ngoba ngesikhathi sokushisa kwemini kumiswa daba - ukuzimisela emphumeleni amandla isezingeni izimo ejwayelekile, uwahlukanise ngokwehlukile. Temperature abakhethiwe sokubalwa 298K (25 degrees centigrade) Pressure - 1 emkhathini. Ngaphezu kwalokho, iphuzu elibalulekile, okuyinto kuwufanele ukunaka Kuyaphawuleka ukuthi ukushisa kumiswa nganoma yisiphi izinto ezilula zero. Lokhu kunengqondo, ngoba izinto ezilula musa yakha ngokwabo, okungukuthi, akukho ukusetshenziswa kwamandla kagesi nesenzakalo yabo.

tincenye thermochemistry

Lesi sigaba yokuthakwa kwamakhemikhali yesimanje anencazelo ekhethekile, ngoba lapha kwenziwe izibalo ezibalulekile Imiphumela elisetshenziswa ezishisayo khona amandla kagesi. Ngo thermochemistry, kunemibandela eminingi futhi imiqondo abalulekile isebenze ukuze uthole imiphumela oyifunayo. I enthalpy (? H) ubonisa ukuthi ukusabela chemical senzeka irherho le-closed, kwakungekho nomthelela impendulo ezinye reactants, ingcindezi kwaba njalo. Lokhu ukucaciseleka ikuvumela ukukhuluma mayelana nokunemba izibalo kwenziwa.

Kuye onjani ukuphendula kubhekwa, ubukhulu kanye uphawu umphumela ezishisayo okuholela ingahluka kakhulu. Ngakho-ke, zonke ukuguqulwa ezihilela yokubola izinto eziyinkimbinkimbi ku izingxenye eziningana ezilula, kucatshangwa ukushisa ukumuncwa. Ixhuma sebuningini ukusabela kokuqala okubalulekile umkhiqizo eziyinkimbinkimbi ephelezelwa ukukhululwa kwe amanani ezinkulu zamandla.

isiphetho

Ekuxazululeni iyiphi inkinga thermochemical isicelo algorithm efanayo yezenzo. Okokuqala, ethebuleni kunqunywa ngayinye ingxenye ukuqala, kanye imikhiqizo ukuphendula ngobungako ukushisa kumiswa, ungakhohlwa isimo ekuhlanganisweni. Ngokulandelayo, Hess umthetho ahlomile lilinganisa ukunquma amanani engaziwa.

Ngokukhethekile kufanele kukhokhelwe akhawunti izici stereochemical ekhona ngaphambi ketshezi kokuqala noma yokugcina ezothando ethile. Uma yokusabela izinto ezilula, ukushisa yabo esezingeni Ukwakheka ilingane no-zero, okungukuthi, izingxenye ezifana azinamphumela phezu yi etholwe izibalo. Zama ukusebenzisa ulwazi yokusabela ethize. Uma sithatha njengesibonelo inqubo kumiswa yensimbi oxide (Fe ³⁺⁾ metal emhlophe ngokunikhumbuza ukusabela ne-graphite, ukubaluleka inkomba zingatholakala heats ejwayelekile kumiswa. Ukuze yensimbi oxide (Fe ³⁺⁾ kuzoba -822,1 kJ / Mol ngokuba graphite (imfuyo elula) zero. Ukusabela okuholela ukhiqiza i-carbon monoxide (CO), okuyiwona inkomba inenani ka - 110,5 kJ / Mol, kuyilapho ukushisa kumiswa ezikhishwe yensimbi okuhambelana zero. Ukuqopha heats esezingeni kumiswa Ngalokuhlanganisa tinchubo chemical libhekene kanje:

_Mayelana 298 H = 3 × (-110,5) -? (-822,1) = -331,5 + 822,1 = 490,6 kJ.

Ukuhlaziya etholwe umthetho Hess yi ezinombolo, kungenzeka ukwenza isiphetho esinengqondo ukuthi inqubo kuyinto ukuguqulwa endothermic, isb ke eqala zatrachivaniya amandla yensimbi ukunciphisa ukusabela oxide yayo ferric.