Isihloko
I-methyl red ne-methylene blue: indlela inkomba ye-Tashiro esebenza ngayo
Inkomba exubile ye-Tashiro ihlanganisa i-methyl red ne-methylene blue ukuze kube lula ukubona ushintsho ku-titration ye-asidi nesisekelo. I-methyl red inikeza ukusabela okuncike ku-pH; i-methylene blue iguqula ukugqama komehluko phakathi kwemibala evelayo. Ukushintsha ukusuka kokuluhlaza okotshani kuya kokunsomi kule ngxube akufanele kuthathwe njengokuthi udayi oluhlaza okwesibhakabhaka wenza ushintsho lwawo olwaziwayo lokuncishiswa ube sesimweni esingenambala.
Ukwakheka kwengxube kubalulekile. Igama elisebhodleleni likhomba iqembu lezinkomba, kodwa ilabhorethri isadinga ukwazi izithako, ushintsho olubhaliwe, nendlela echaza ukuthi kufanele kumiswe nini ukufaka i-titrant.
Okunikelwa udayi ngamunye
I-methyl red iyinkomba ye-asidi nesisekelo. Isimo sayo esineprothoni nesingenayo simunca ukukhanya okubonakalayo ngezindlela ezihlukene, ngakho ukushintsha kwezilinganiso zalezi zimo kudala ushintsho lombala lapho i-pH ishintsha. Ngokwesibonelo, i-Sigma-Aldrich icacisa ushintsho ukusuka kokuphinki kuya kokuphuzi phakathi kwe-pH 4.2–6.2 nge-reagent yayo ye-methyl red.
Ukufaka ingxenye eluhlaza okwesibhakabhaka kuguqula lokho iso elikubonayo: uhlangothi olubomvu lubonakala lunsomi kakhulu, kanti uhlangothi oluphuzi oluhlanganiswe nokuluhlaza okwesibhakabhaka lubonakala luluhlaza okotshani. Lokhu kuvame ukuchazwa ngokuthi ukuhlungwa kwemibala yenkomba. Umehluko obalulekile uphakathi kwengxenye esabela ebu-asidini nengxenye eguqula indlela lokho kusabela okubonakala ngayo. Ukuxuba odayi akuguquli i-methylene blue ibe isilinganisi se-pH esisebenza kuzo zonke izimo.
Qhathanisa lezi zimo ezintathu ngaphambi kokuchaza umbala:
| Uhlelo lwenkomba | Yini ekhiqiza isignali? | Lokho obukayo angakuthola |
|---|---|---|
| I-methyl red iyodwa | Ukushintsha kwesimo se-asidi nesisekelo | Isixazululo sesidlule ebangeni lokushintsha kwe-pH laleyo nkomba |
| I-methyl red kanye ne-methylene blue | Ukusabela ku-pH okubonwa ngemibala ehlanganisiwe | Inkomba exubile isifinyelele ekubukekeni okuncike ekwakhekeni kwayo |
| I-methylene blue ohlelweni olunciphisayo | Ukuncishiswa kukadayi oluhlaza okwesibhakabhaka, okungase kulandelwe ukufakwa kwe-oksijini futhi | Kwenzeka ukusabela kwamakhemikhali kwe-redox; lokhu akukhombi indawo yokugcina ye-titration |
Umugqa wokugcina uchaza ukuhlolwa okuhlukile. Embukisweni webhodlela eliluhlaza okwesibhakabhaka wase-Oxford, i-glucose esendaweni ene-alkali inciphisa i-methylene blue ibe sesimweni esingenambala, bese i-oksijini efakwayo ibuyisela umbala oluhlaza okwesibhakabhaka. Lezo zimo zichaza umjikelezo we-redox, hhayi ukufundwa kwe-asidi nesisekelo okuhloswe ngenkomba ye-Tashiro. Lo mehluko obanzi uchazwa ekhemistri ye-redox ye-methylene blue.
Ukwakheka okubhaliwe nesiqondiso sokushintsha kombala wako
Ishidi lobuchwepheshe le-ITW Reagents lomkhiqizo 282430, uhlelo 5 lwango-Okthoba 2018, licacisa i-methyl red engu-100 mg ne-methylene blue engu-50 mg, namanzi angu-10.4 mL kanye ne-ethanol engenamanzi eyanele ukwenza 100 mL. Likhomba lo mkhiqizo njengowenzelwe ama-titration e-ammonia futhi libhala ukuthi uba bomvu-nsomi ku-pH 4.4 futhi ube luhlaza okotshani ku-pH 5.8.
Lokhu kunikeza umdwebo olandelayo oncike kulokhu kwakheka:
pH 4.4, obomvu-nsomi → i-pH iyenyuka → pH 5.8, oluhlaza okotshani
pH 5.8, oluhlaza okotshani → i-pH iyehla → pH 4.4, obomvu-nsomi
Umcibisholo uchaza isiqondiso sokushintsha phakathi kwebanga lenkomba. Awubeki noma yimuphi umkhawulo waleli banga njengendawo yokumisa kukho konke ukuhlaziya. Ishidi alinikezi indawo yokugcina empunga eqondile, ngakho le ncazelo ayikwazi ukunikeza i-pH yendawo empunga esebenza kuzo zonke izimo.
Qaphela futhi ukuthi okuluhlaza okotshani ku-pH 5.8 kusene-asidi ezimweni ezivamile zezixazululo zamanzi. Ukubiza imibala ngokuthi “i-asidi” nokuthi “i-alkali” kuphela kungafihla lokhu: uhlangothi oluluhlaza okotshani lunama-pH aphezulu kunolunye uhlangothi loshintsho, kodwa alubona ubufakazi bokuthi isampula ingaphezu kwe-pH 7.
Okukalwa ngempela yi-titration ye-ammonia
Inkomba ibonisa ukuthi kufanele kufundwe nini i-burette. Inani lento ehlaziywayo litholakala enanini elikaliwe le-titrant esetshenzisiwe, ekugxileni kwayo okumisiwe, nasezilinganisweni zamakhemikhali zokusabela. Umbala oluhlaza okotshani ogqame kakhulu, wona wodwa, awulinganisi ukuthi kune-ammonia eningi.
Njengesibonelo sendlela ethile, i-EPA Method 350.2 yakudala eshicilelwe kabusha yi-NEMI ikhipha i-ammonia ngokuyihwamulisa bese ihlanganisa umhwamuko ku-boric acid, futhi iyilinganisa nge-titration esebenzisa i-sulfuric acid enokugxila okumisiwe. Inkomba yayo exubile isebenzisa izingxenye ezimbili zevolumu zesixazululo esiyisisekelo se-methyl red engu-0.2% nengxenye eyodwa yevolumu yesixazululo esiyisisekelo se-methylene blue engu-0.2%, zombili ziku-ethanol engu-95%. Le ndlela iyalela umhlaziyi ukuba aqhathanise indawo yokugcina nesampula engenayo into ehlaziywayo equkethe amavolumu ahambisanayo amanzi ne-boric acid.
Le recipe nokwakheka komkhiqizo othengiswayo okungenhla kunesilinganiso esifanayo sezisindo zodayi, kodwa kunokugxila nezithako zezincibilikisi ezingafani. Ngakho ukufana kwesilinganiso akubona ubufakazi obanele bokuthi amabhodlela amabili angasetshenziswa ngokushintshana. Le nqubo futhi iphathelene ne-nitrogen esesimweni se-ammonia futhi ikubeka ngokucacile ukuthi ayihlanganisi i-nitrogen ephelele ye-Kjeldahl. Ukusebenzisa inkomba efanayo akwenzi izindlela ezimbili zokulinganisa i-nitrogen zibe ukuhlolwa okufanayo.
Sebenzisa lowo mbhalo ukuze uqonde inqubo yokuhlaziya ecacisiwe, hhayi ukuze ucabange ukuthi uhlelo lwawo lwakudala lulawula izimfuneko zamanje zokubika. Indlela eyamukelwe yilabhorethri kufanele ikhombe uhlelo olusebenzayo kanye nezindlela zalo zokulawula ikhwalithi.
Indawo yokugcina nendawo yokulingana ngokwamakhemikhali azifani
I-IUPAC ichaza i-titration nendawo yayo yokugcina ngokubona ukuthi ukusabela sekuqediwe; indawo yokulingana ihambisana nokulingana okuqondile ngokwamakhemikhali. Isignali ebonakalayo ilusizo uma iseduze ngokwanele naleyo ndawo ngokwenhloso yendlela esetshenziswayo.
Ake sithi abahlaziyi ababili benza i-titration kumasampula afanayo. Omunye uyama lapho isixazululo sifana nesampula engenayo into ehlaziywayo ecacisiwe. Omunye uyaqhubeka kuze kubonakale umbala onsomi ogqame kakhulu. Umhlaziyi wesibili ukhethe indawo yokugcina ehlukile futhi angase asebenzise i-titrant eyeqile. Ukuvumelana ngegama lombala wokugcina akuqinisekisi ukuvumelana ngenani elikaliwe.
Yingakho umhlahlandlela wokuqeqesha kufanele ucacise into yokuqhathanisa, izimo zokubuka, kanye nombandela wokuthi umbala kufanele uhlale isikhathi esingakanani ngokwendlela esetshenziswayo. Isithombe esisesikrinini singachaza isiqondiso soshintsho, kodwa into yokuqhathanisa yaselabhorethri ibeka isisekelo sokwenza isinqumo lapho kwenziwa umsebenzi.
Ukuhlola okusebenzisekayo ngaphambi kokushintsha inkomba noma ukuphenya inkinga yayo
Sebenzisa leli phepha lokusebenza lapho umbala ubukeka ungalungile noma kuhlongozwa ibhodlela lokushintsha elikhona:
| Okufanele kuhlolwe | Okufanele kubhalwe | Kungani kuthinta ukuchazwa |
|---|---|---|
| Ubunikazi be-reagent | Amagama abo bobabili odayi nekhodi yomkhiqizo | Inkomba exubile enegama elicishe lifane ingaqukatha amakhemikhali ahlukile |
| Ukwakheka | Ukugxila kodayi, isilinganiso, nesincibilikisi | Isilinganiso sodwa sishiya umehluko obalulekile ungacacisiwe |
| Inqubo | Indlela, uhlelo, ukufakwa kwenkomba, nesiqondiso se-titration | Incazelo yebhodlela ayichazi konke ukuhlaziya |
| Okubhekiselwa kukho endaweni yokugcina | Isampula engenayo into ehlaziywayo noma into yokuqhathanisa edingekayo nomthetho wokumisa | “Okunsomi” kungasho ukubukeka okuhlukahlukene okubonakala kwehlukile |
| Ukuziphatha okungalindelekile | Ukuthi ushintsho lulandela yini ukufakwa kwe-titrant, ukuyekwa kumile, noma ukufakwa komoya | Umjikelezo wokuphela kombala oncike esikhathini udinga uphenyo olungagcini ku-pH |
Bheka ukwehluleka kwesampula engenayo into ehlaziywayo noma ushintsho lombala olungachazeki njengesizathu sokuphenya i-reagent nendlela ngaphambi kokubika imiphumela. Ukufaka udayi owengeziwe kuze isampula ibukeke ijwayelekile kushintsha izimo zokubuka futhi kungafihla inkinga yokuqala.
Ukuze ukhethe umsebenzi ofanele kadayi ekuhlolweni okuhlukile, qala ngokufunda nge-methylene blue ekuhlolweni kokuhlaziya. Kuma-titration e-Tashiro, gcina ukwakheka kwengxube yodayi, indawo yokugcina ebonakalayo, nokubala kokuhlaziya kubhalwe ndawonye.