Crystalization vs Recrystallization
Hauv crystallization, crystalline precipitates yog tsim. Precipitates tuaj yeem tsim nyob rau hauv ob txoj kev; los ntawm nucleation thiab particle loj hlob. Hauv nucleation, ob peb ions, atoms lossis molecules tuaj ua ke los tsim cov khoom ruaj khov. Cov khoom me me no hu ua nuclei. Feem ntau, cov nuclei tsim nyob rau saum npoo ntawm cov khoom raug tshem tawm. Thaum cov nucleus no nthuav tawm ntxiv rau cov ions, atoms lossis molecules, ntxiv nucleation lossis kev loj hlob ntxiv ntawm cov khoom tuaj yeem tshwm sim. Yog hais tias nucleation tseem tshwm sim, ib qho precipitate uas muaj ntau qhov me me tshwm sim. Hauv qhov sib piv yog tias kev loj hlob predominates, ib qho me me ntawm cov khoom loj yog tsim. Tus nqi ntawm nucleation nce nrog nce tus txheeb ze supersaturation. Feem ntau, nag lossis daus tshwm sim qeeb. Yog li thaum lub precipitating reagent ntxiv maj mam mus rau ib qho kev daws teeb meem ntawm cov tshuaj ntsuam xyuas, qhov supersaturation tuaj yeem tshwm sim. (Supersaturated tov yog cov tshuaj tsis ruaj khov uas muaj cov kuab tshuaj ntau dua li cov tshuaj saturated.)
Crystalization
Crystalization yog cov txheej txheem ntawm precipitating crystals los ntawm kev daws vim muaj kev hloov pauv hauv cov kua dej ntawm cov kua dej hauv cov tshuaj. Nov yog txheej txheem sib cais uas zoo ib yam li nag lossis daus.
Precipitates yog cov khoom uas muaj cov khoom hauv cov tshuaj. Qee zaum cov khib nyiab yog tshwm sim los ntawm cov tshuaj tiv thaiv hauv cov tshuaj. Cov khoom no thaum kawg yuav nyob rau hauv vim lawv qhov ntom, thiab nws yog hu ua precipitate. Nyob rau hauv centrifugation, lub resulting precipitate kuj hu ua pellet. Cov tshuaj saum toj no cov nag lossis daus yog hu ua supernatant. Lub particle loj nyob rau hauv precipitate hloov ntawm lub sij hawm mus rau lub sij hawm. Crystals tuaj yeem lim tau yooj yim, thiab lawv loj dua.
Qhov sib txawv ntawm txoj kev crystallization los ntawm cov nag lossis daus ib txwm yog tias, cov khoom tshwm sim yog siv lead ua. Crystalline precipitates yog lim tau yooj yim dua thiab huv. Cov siv lead ua particle loj tuaj yeem txhim kho los ntawm kev siv cov tshuaj dilute thiab ntxiv cov precipitating reagent maj mam thaum sib tov. Qhov zoo ntawm cov siv lead ua thiab kev txhim kho hauv filterability tuaj yeem tau los ntawm kev sib cais thiab recrystallization ntawm cov khoom. Crystallization tuaj yeem pom hauv qhov xwm txheej thiab. Nws yog feem ntau nqa tawm dag rau ntau hom siv lead ua thiab purification.
Recrystalization
Recrystallization yog ib qho txheej txheem los ntxuav cov pob zeb uas tau los ntawm txoj kev crystallization. Txawm hais tias crystallization cais cov compound nyob rau hauv yuav luag dawb huv daim ntawv, thaum lub crystals tsim ib co ntawm impurities yuav cuab nyob rau hauv nws. Los ntawm txoj kev recrystallization, cov impurities no tuaj yeem raug tshem tawm kom ntev dua.
Feem ntau cov muaju yog yaj nyob rau hauv me ntsis ntawm cov kuab tshuaj kub thiab tso cai rau yaj tag. Thaum qhov no tau tso cai kom txias qeeb (tej zaum yuav yog tom qab lim), cov muaju yuav tshwm sim dua. Cov crystals no tsis muaj impurity. Cov crystals tuaj yeem sib cais los ntawm kev lim cov tshuaj dua. Cov txheej txheem recrystallization tuaj yeem ua tau ntau txoj hauv kev, thiab ob peb zaug txhawm rau ua kom purity ntawm qhov xav tau siv lead ua.
Qhov txawv ntawm Crystallization thiab Recrystallization yog dab tsi?
• Recrystallization yog ua tiav rau cov muaju uas tsim los ntawm txoj kev crystallization.
• Crystallization yog txheej txheem sib cais. Recrystallization yog siv los ntxuav cov compound tau txais los ntawm crystallization.
