Indlela yokuhlaziya ye-Gravimetric: umqondo, izinhlobo kanye nezici

Yiziphi izimpawu zokuhlaziywa kwe-gravimetric? Ake sicabangele ngokuningiliziwe okuyisisekelo kanye nezinhlobo zazo.

Okucacile

Indlela ye-gravimetric yokuhlaziywa ngokusekelwe emthethweni wokulondolozwa kwezinto eziningi kanye nokwakheka kokubunjwa kusekelwe. Kulokhu, kuncike ekulinganiseni okunembile kobuningi bezinto ezifunayo, okutholakala njengekhamera elinamakhemikhali aziwayo. Indlela ye-gravimetric yokuhlaziywa ihlukaniswe ngamaqembu amathathu amakhulu: ama-distilation, ukuzihlukanisa, imvula.

Mayelana nendlela yokukhetha

Isekelwe ekufakweni kwezinto ezifunayo kusukela ekuhlaziyeni kwemithi yamakhemikhali ngendlela ekhululekile kanye nesisindo esinembile esilandelayo. Isibonelo, indlela enjalo ye-gravimetric yokuhlaziywa kokulinganisa yenza kube lula ukucacisa okuqukethwe komthamo wezinsalela zomlotha emafutheni aqinile. Ukufeza izibalo, isisindo se-crucible, ushise isampula kawoyela kulo, futhi umlotha ophelile ulinganiselwe. Njengoba inqwaba yezinsalela, isibalo sokulinganisa sibalwa kusukela kwifomula yenqwaba yempahla engxenyeni.

I-distillation

Le ndlela yokuhlaziywa i-gravimetric kokuqukethwe, ngoba ithatha ukususwa okuphelele kwesakhi esibalwe njenge-gaseous compound kanye nesisindo esilandelayo sezinsalela eziqinile. Ukusebenzisa le nqubo, umuntu anganquma okuqukethwe komswakama wezinto ezihlukahlukene, ukubala okuqukethwe okulinganiselwe emanzini e-cristalline amanzi e-crystallization. Ukuze wenze isibalo esinjalo, ubuningi bezimpawu zesampula zezinto ezikhethiwe kuqala. Khona-ke, isici okumelwe sinqume sisuswe ngokuphelele kuso. Umehluko phakathi kobuningi ngaphambi kokubala noma ukomisa futhi emva kwabo ubukhulu bezinto ezitholakalayo zamakhemikhali. Ngomthamo wendiza enkulu, ukubala okulinganiselwe kwenziwa.

Indlela yokwelashwa

Iyini le ndlela yokuhlaziya? Indlela ye-gravimetric yemvula isekelwe ekujuleni kwenani le-ion elifunayo njengezinto ezincane ezincibilikayo ezinomakhemikhali athile. I-precipitate eholelekile ihlungiwe, ihlanjwe, isomisiwe, i-calcined. Ngemva kokukhipha ngokuphelele amanzi kuwo, isilinganise. Ukwazi ubuningi bomdanso, kungenzeka ukubala okuqukethwe okulinganiselwe kwama-molecule noma i-ion yezinto ezifunayo kwisampula ngaphansi kwesifundo.

Izidingo zokwelashwa ekuhlaziyweni kwe-gravimetric

Noma kunjalo - iyiphi indlela ye-gravimetric yokuhlaziywa? Ukusebenza okuyinhloko endleleni yokubeka imali kuhlobene nenqubo yokuchithwa kwemvula. Ukunemba komphumela okwenziwe ngesikhathi sokuhlaziywa ngokuqondile kuxhomeke ekubunjweni kwamakhemikhali wezinto, isakhiwo se-sediment, kanye nezinga lokuhlanzeka. Ngaphezu kwalokho, izibalo zihlobene nokuziphatha kwezulu ngesikhathi sokuma nokubala. Ngokuvamile kukhona ushintsho ekwakhiweni kwamakhemikhali okwenyuka ngesikhathi sokubala. Ifomu elikhunjulwe yi-chemical composition of the obtained precipitate.

Izindlela eziyinhloko zokuhlaziywa kwe-gravimetric kuthatha umphumela onembile. Yingakho izidingo ezithile zifakwe efomini ye-gravimetric neyesikhunta.

1. Kumele kube nokuziphendulela okuncane, okuyiyona ingxube yamakhemikhali engasebenzi.
2. Kumelwe wenze ama-crystals amakhulu. Kulesi simo, ngeke kube nezinkinga ohlelweni lokuhlunga, njengoba ama-pores awahlanganisiwe. Ama-crystals amakhulu ane-surface encane, i-adsorbed ngesivinini esincane esivela kwisixazululo esikhona, angasuswa kalula. Ama-Amorphous precipitates ensimbi ye-hydroxide (3) avumela ukungcola ngaphandle kwezinkinga, kunzima ukugeza kude nokungcola, ukuhlunga kwalesi sakhi kuyashesha.
3. Ngokuphelele futhi isikhathi esifushane sokuhamba ngendlela efakazelayo.

Izidingo zefomu lokuvusa

Ake sihlaziye indlela ye-gravimetric yokuhlaziywa. Okuyinhloko yendlela ukuthi ukuthi ukunemba kubalulekile kuwo. Ifomu le-gravimetric kufanele libe nefomula ethile yamakhemikhali, esetshenziselwa ukubala okuqukethwe kwisampula yezingxenye ezithile. I-sediment ekhonjiwe ngesikhathi sokupholisa futhi inqubo enesisindo akufanele ithathe umswakama wamanzi emoyeni, alulame noma aphilise. Uma le sediment inezici ezifanayo zomzimba, okokuqala iguqulwa ibe ifomu elizinzile besebenzisa ama-reagents akhethekile amakhemikhali. Isibonelo, uma kudingeka ukubala ingxenyana enkulu ye-calcium carbonate kulezi zinto, ifomu le-gravimetric le-calcium oxide, elikwazi ukukhipha i-carbon dioxide namanzi, liguqulwa libe yi-calcium sulfate. Ngenxa yalokhu, i-calcined precipitate iphathwa nge-sulfuric acid, ibuka umbuso wokushisa (500 ° C).

I-Tableware yesifundo

Yini edingekayo ukuqhuba indlela enjalo yokuhlaziywa? Inguqulo ye-gravimetric ihilela ukusetshenziswa kwezidakamizwa ezikhethekile zamakhemikhali amakhulu. Lapha, izibuko ezincane ezinamabhande ahlukene, ivolumu, izinti zezibuko, ukubukela ingilazi, i-porcelain crucibles, amabhokisi eklasi. Izindlela zokuhlaziywa kwe-gravimetric nezetrimetric zisho ukusetshenziswa kweziqukathi ezihlanzekile kuphela, ngakho-ke azikho amaphutha kuzibalo. Ama-dry spots noma amaconsi akhombise ukuthi kukhona izingxenye ze-fat on the surface glass. Ukunqunywa kuzomathela kuluhlu olunjalo, ngenxa yalokho, ukudluliselwa okuphelele kusihlungi kuyoba nzima nakakhulu. Indlela yokwenza indlela ye-gravimetric yokuhlaziya ihlanganisa ukugeza ngokucophelela izitsha nge-detergents. Ukuze kuhlanzwe izingulube ze-porcelain, kusetshenziselwa i-hydrochloric acid eshisayo, isisombululo se-chromium ingxube. Kunconywa ukushisa i-cookware ehlanzekile ngaphambi kokuqala umsebenzi.

Izinsiza zokucwaninga

Uyini umehluko emkhatsini we-gravimetric indlela yokuhlaziywa? Okuyinhloko yendlela yokuzimisela kokulinganisa kwezingxenye zento. Imishini ezobaluleka kulezo zifundo ifana nalokhu esetshenziselwa ukuhlaziywa okufanele. Ngokwezinhloso ezingokoqobo, amanzi okugeza, izingxenyana ze-porcelain triangles, ukomisa amabhakede, ama- crucible, ama- muffle, ama- gas burners azofuneka. Ukuze kubalwe ama-gas burners we-porcelain crucibles, kusetshenziselwa ama-triangles akhiwe ngamatayipi okugcoba, ahlanganiswe nesisekelo sensimbi. Khetha unxantathu walesi sayizi ukuze i-crucible ihambe kuyo ingxenye yesithathu yokuphakama. Ama-crucible aziswe esithandweni somlilo ngokusebenzisa amathuluzi amakhulu aphethe amathiphu aphezulu, aphezulu. Akumelwe afakwe ngaphakathi. Ngaphambi kokusetshenziswa, ukuphela kwe-forceps kuhlanzwa, kubalwa kwi-burner yegesi noma kuhhavini. Ama-Desiccators asetshenziselwa ukupholisa izinto ezicubungula noma ezifudumele ekamelweni lokushisa. Liyisikebhe esinama-glass, esembozwe ngesembozo somhlabathi. Ingxenye engezansi ye-desiccator igcwele izinto eziphilayo:

• Izingxenye ze-calcium oxide;
• I-Phosphorus oxide (5);
• I-asidi ye-sulfuric ehlanganisiwe.

I-sulfuric acid ithatha umswakama ngamandla. Ukusebenza ne-desiccator, kubalulekile ukuqinisekisa ukuthi izingxenye ezihlanjululwe zinomugqa wokugcoba.

Imithetho yokusampula yokuhlola

Ukuhlukaniswa kwezinqubo zokuhlaziywa kwe-gravimetric kubhekwa kuhilela ukusebenza ngezinto. Isilinganiso yisampula esinezinto ezincane zokwaziswa okuhlaziyekile, okunamakhemikhali, izakhiwo zomzimba uphawu lwe-lot main. Ukufaneleka kwesampula kuthinta ukunemba kwezimpawu zamakhemikhali nezomzimba kanye nokwakhiwa kwamakhemikhali okuqukethwe okuhlaziywa. Ukukhethwa kwesampula esenzelwe kwenziwa ngokunakekelwa okukhethekile, ngaphandle kwalokho kungenzeka ukuthi iphutha alinembile, ukuthola imiphumela engalungile yocwaningo. Kumele kukhunjulwe ukuthi izingcezu ezinkulu zamakhemikhali zingase zihluke kakhulu kunothuli. Ngakho-ke, kunezinketho ezintathu:

• Isampula eyisisekelo - esidingekayo esigabeni sokuqala sohlolo;
• Ipasipoti, noma ukuhlola kwelabhutrikhi - etholakala ngokunciphisa isampula sokuqala esiyingcosana esidingekayo ekuhlaziyweni kwamakhemikhali kanye nomzimba;
• I-Analytical - ikhethwe esampula ye-laboratory yokuhlaziywa kwamakhemikhali.

Kunesigaba esinjalo njengokhemikhali yokuhlaziya. Indlela ye-gravimetric yokuhlaziywa ingenye yezindlela zokusungula ukwakheka kokulinganisa kwezinto. Ukuze ugweme ukuguquka kokuqukethwe umswakama kanye nokwakhiwa kwamakhemikhali wezinto, izinto zokuhlaziywa kwe-gravimetric zigcinwa ezikhwama zivaliwe zivalwe ngamabhodlela. Ingxenye yesampula idinga ukuhlaziywa okuqondile, kanti ezinye zihlala njengendawo yokugcina.

Ukulungiselela isampula yocwaningo

Isampula ibhekwa njengesiyingcosana esincane sampula yokuhlaziya yesampula ehlaziyiweyo, esilinganiswa ukuhlaziywa kwamakhemikhali. Ubukhulu besampula bunendima ebalulekile ekuzimiseleni kokulinganisela. Uma isampula esithathwa kakhulu ekuhlaziyweni kwe-gravimetric, umphumela onembile umphumela uzoba. Kodwa ngasikhathi sinye, inqubo yokuhlunga isiphumo esiphuthumayo, i-calcination yayo, ukugeza kuyinkimbinkimbi. Ngenxa yalezi zizathu, isikhathi sokuhlaziya sithandwa kakhulu. Emasampula amancane, ukunemba kokuzimisela kunciphise kakhulu. Ukwenza isisindo samasampula ezinsimbi eziqinile, sebenzisa i-glass watch elincane. Izinto ezinokuzenzekelayo, izinto ezincane kufanele zilinganiswe esikhwameni esivaliwe.

Izimo zokukhuphuka

Ngethulo lale ndaba, isethulo sizoba umbono omuhle. Indlela ye-gravimetric yokuhlaziywa ngalesi sigaba ihilela ukudluliswa kokulinganisa kwesakhi esifisekayo kumuthi othile wamakhemikhali. Ukwazi ubuningi bomdanso, ungabala iphesenti yenkampani enqunywe. Ukunemba kokuhlaziywa kuxhomeke ekuphelelweni kokugcinwa kwemali. Phakathi kwezizathu zokuthi kungani yonke into ebalwe ibalwa, iyakwazi ukukhuluma ngokungapheleli kwemvula. Kuyinto engenakwenzeka ukufeza ukushisa okuphelele, kungenzeka kuphela ukunciphisa ukulahlekelwa okungenzeka. Ukuze kuhlaziywe, i-precipitant ikhethiwe - i-precipitate cishe engapheli. Kuthathwa ngokweqile ukugwema ukusabela okunjalo kwamakhemikhali. Kunezimo ezithile okumelwe zigcinwe ukuze zithole isikhala se-crystalline:

• Kusukela ezixazululweni ezihlungayo, imvula yenziwa ngezixazululo ezibuthakathaka ze-precipitant;
• Izixazululo ezifudumayo zithathwa yizikhukhula ezishisayo.

Ukuze kuhlolwe, i-reagent ye-qualitative ikhethwe ion ebonakalayo. Kulukhuni ukukhetha ukucacisa okuqondile kwe-ion ngayinye okumelwe iqiniseke. Kulesi sixhumano, izinhlayiya ezingaphazamisa ukuchithwa okuphelele zingagubungulwa, noma zingasuswa esixazululweni esiphenywe ngaphambi kokuhlaziywa kokulinganiswa.

Kuyinto engenakwenzeka ukukhetha izakhi eziqondile kuzo zonke ion ezibonakalayo. Khona-ke kudingekile ukuthi usebenzise i-i-masking ions ephazamisa ukuchithwa, noma ukuwahlukanisa nesisombululo ngaphambi kwemvula. Ukwazi okwehlukile kwesikhala se-crystalline, umuntu angasebenzisa izimo ezikhuthaza ukwakhiwa kwamakhekhedi amakhulu.

1. Imvula yenziwa ezixazululweni ezishisayo ezihlanjululwe ngesikhuni esithathwe ngokuhlushwa okuncane. Uma kusetshenziselwa ukufudumala, uketshezi kwamakhekhedi amancane kwanda, ngakho-ke ukuhlushwa kwe-precipitant kanye ne-ions kule nkinga kwanda. Ngenxa yalesi simo, amakristalu amakhulu akhiwa, angenayo isikhathi sokuqothula uma esha.
2. I-precipitant ishayela kulesi sitshalo esinqunyiwe ngesilinganiso esincane. Ukuze uxube, sebenzisa induku yesilazi, okufanele ingathinti phansi nezingange zengilazi. Ngokuvuselela, ukukhula kwe-crystal kuyakhuthazwa, njengoba inani le-crystal centers liyehla.
3. Melana nomlotha wamahora amaningana. Izidakamizwa zama-Amorphous ziyancipha ngaphansi kwezimo ezikhethekile, ngoba zijwayele ukuhlunga izidakamizwa ezihlukahlukene nokubonakala kwezixazululo ze-colloidal.

Izinkinga zokuhlaziywa kwe-gravimetric

Ukuchithwa kokubala okulinganiselwe kuthintwa yikhwalithi yesidumbu. Uma ingcolile, ukunemba kwezilinganiso kunciphisa kakhulu, iphutha landa. Isizathu sokungcola sisekukhusheni, lokho kungukungena kwezinto zangaphandle. Kunezinhlobo ezimbili zokukopisha:

• Ukukhangisa okuphezulu;
• Ukubanjwa.

Ukuze uhlole ukuphelela kwesikhala se-ion ehlukanisiwe, amaconsi amaningana we-reagent ayengezwe kwisixazululo esakhiwe ngaphezu kwe-precipitate. Njengoba kunemvula ephelele ye-ion ehlukanisiwe, ikhambi lizohlala libala.

Isiphetho

Ukuhlaziywa okufaneleko kufaka hlangana ukuzimisela kokulinganisela kwama-ion angakahleliko ekutjenzisweni. Imisebenzi eyinhloko yokuhlaziywa kwekhwalithi ukutholakala kwesampula esikhethiwe kanye nokuhlonza izingxenye ezithile: ion noma izakhi zamakhemikhali, into ethile noma iqembu elisebenzayo. Indlela yokulinganisa i-fractional efanelekile ekuphenyweni kwemixube elula, lapho ifuna inombolo encane yezingxenye. Ukuhlaziywa okunjalo kwe-gravimetric, amasampuli ahlukene kanye nenombolo engadingekile yokusabela okufanisayo kuyadingeka. Ukuze unqume ngokugcwele izingxenye ezingavamile kuzinto eziphenywayo, ingxube yokuqala ekuqaleni ihlukaniswe yaba "amaqembu okuhlaziya" ahlukene, bese ion ngayinye itholakala ngosizo lwezenzo ezithile. Ukuhlaziywa okunembile kwekhwalithi kwenza kube lula ukwandisa ukwethembeka kolwazi oluhlaziya ukuhlaziya. Ngaphambi kokuqhubeka nokuhlaziywa kokulinganisa, kubalulekile ukuqonda ukwakheka kokufaneleka kwesampula ukuze ukhethe inqubo ehle.