Inqaku
I-methyl red ne-methylene blue: indlela esisebenza ngayo isalathisi se-Tashiro
Isalathisi esixutyiweyo se-Tashiro sidibanisa i-methyl red ne-methylene blue ukuze kube lula ukubona utshintsho kwititration yeasidi nesiseko. I-methyl red inika impendulo exhomekeke kwi-pH; i-methylene blue iguqula umahluko phakathi kwemibala ebonakalayo. Utshintsho olusuka kumbala oluhlaza okwengca luye komfusa kulo mxube alufanele lutolikwe njengokuba idayi eluhlaza okwesibhakabhaka yenza iredukshini yayo eyaziwayo ibe kwimo engenambala.
Indlela owenziwe ngayo umxube ibalulekile. Igama elisebhotileni lichaza udidi lwesalathisi, kodwa ilabhoratri isafuna ukwazi izithako, utshintsho olubhaliweyo, nendlela echaza ukuba kufuneka kuyekwe nini ukongeza i-titrant.
Igalelo ledayi nganye
I-methyl red sisalathisi seasidi nesiseko. Iimo zayo ezineprotoni nezingenaprotoni zifunxa ukukhanya okubonakalayo ngeendlela ezahlukileyo, ngoko ukutshintsha komlinganiselo wazo kuvelisa utshintsho lombala njengoko i-pH itshintsha. Umzekelo, i-Sigma-Aldrich ichaza utshintsho olusuka kupinki luye kumthubi kuluhlu lwe-pH 4.2–6.2 kwirejenti yayo ye-methyl red.
Ukongeza icandelo eliluhlaza okwesibhakabhaka kuguqula oko kubonwa liliso: icala elibomvu libonakala limfusa ngakumbi, ngoxa icala elityheli elidityaniswe noluhlaza okwesibhakabhaka libonakala liluhlaza okwengca. Oku kudla ngokuchazwa njengokusebenzisa umbala ogqumayo kwisibonakaliso sesalathisi. Umahluko oluncedo uphakathi kwecandelo eliphendula kubuasidi necandelo eliguqula indlela elibonakala ngayo. Ukuxuba ezi dayi akuyenzi i-methylene blue ibe sisixhobo esilinganisa i-pH kuzo zonke iimeko.
Thelekisa ezi meko zintathu ngaphambi kokutolika umbala:
| Inkqubo yesalathisi | Yintoni evelisa umqondiso? | Oko umntu obukeleyo anokukufumanisa |
|---|---|---|
| I-methyl red yodwa | Utshintsho kwimo yeasidi nesiseko | Isisombululo sidlule kuluhlu lotshintsho lwe-pH lweso salathisi |
| I-methyl red kunye ne-methylene blue | Impendulo ye-pH ebonwa ngemibala edityanisiweyo | Isalathisi esixutyiweyo sifikelele kwinkangeleko exhomekeke kumxube waso |
| I-methylene blue kwinkqubo ebangela iredukshini | Iredukshini yedayi eluhlaza okwesibhakabhaka, enokulandelwa yioksideshini kwakhona | Ikhemistri yeredox iyenzeka; oku akuyichazi indawo yokuphela kwetitration |
Umqolo wokugqibela uchaza uvavanyo olwahlukileyo. Kumboniso wase-Oxford webhotile eluhlaza okwesibhakabhaka, iglucose ekwimeko yealkali ibangela iredukshini ye-methylene blue ibe kwimo engenambala, ize ioksijini engenisiweyo ibuyisele umbala oluhlaza okwesibhakabhaka. Ezo meko zichaza umjikelo weredox, hayi isibonakaliso seasidi nesiseko esijoliswe yi-Tashiro. Lo mahluko ubanzi uchazwa kwikhemistri yeredox ye-methylene blue.
Umxube obhaliweyo nendlela otshintsha ngayo umbala
Iphepha lobugcisa le-ITW Reagents lemveliso 282430, uhlelo 5 lomhla ka-Oktobha 2018, lichaza i-100 mg ye-methyl red ne-50 mg ye-methylene blue, kunye ne-10.4 mL yamanzi ne-ethanol engenamanzi eyaneleyo ukwenza i-100 mL. Lichaza ukuba imveliso yenzelwe iititration zeammonia, kwaye libhala ukuba umbala ubomvu-mfusa kwi-pH 4.4, ube luhlaza okwengca kwi-pH 5.8.
Oku kunika lo mzobo ulandelayo, oxhomekeke kulo mxube:
pH 4.4, bomvu-mfusa → ukunyuka kwe-pH → pH 5.8, luhlaza okwengca
pH 5.8, luhlaza okwengca → ukuhla kwe-pH → pH 4.4, bomvu-mfusa
Utolo luchaza indlela yotshintsho kuluhlu lwesalathisi. Aluchazi ukuba isiphelo esinye solu luhlu kufuneka sibe yindawo yokuyeka kuhlalutyo ngalunye. Iphepha alichazi indawo yokuphela engwevu echanekileyo, ngoko akukho pH yendawo engwevu esebenza kuzo zonke iimeko enokuthatyathwa kule nkcazelo.
Qaphela nokuba umbala oluhlaza okwengca kwi-pH 5.8 usesekwimeko yeasidi phantsi kweemeko eziqhelekileyo zezisombululo ezinamanzi. Ukubiza imibala nje ngokuthi “iasidi” ne-“alkali” kunokuyifihla le nyaniso: icala eliluhlaza okwengca licala eline-pH ephezulu kuluhlu lotshintsho, hayi ubungqina bokuba isampulu ingaphezulu kwe-pH 7.
Oko kulinganiswa yititration yeammonia
Isalathisi sibonisa ukuba kufuneka ifundwe nini iburette. Ubungakanani bento ehlalutywayo buvela kubungakanani obulinganisiweyo be-titrant esetyenzisiweyo, kuxinzelelo lwayo olumiselwe ngokuthelekiswa nomgangatho, nakwistoichiometry yentsabelano. Umbala oluhlaza okwengca oqaqambe ngakumbi awulinganisi, ngokwawo, iammonia eninzi ngakumbi.
Njengomzekelo othile wendlela, i-EPA Method 350.2 yakudala ephinde yapapashwa yi-NEMI ikhupha iammonia ngokudistila iyise kwiasidi yeboron, ize ilinganise ubungakanani bayo ngetitration kusetyenziswa iasidi yesalfure exinzelelo lwayo lumiselwe ngokuthelekiswa nomgangatho. Isalathisi sayo esixutyiweyo sisebenzisa imithamo emibini yesisombululo esigciniweyo se-0.2% ye-methyl red nomthamo omnye wesisombululo esigciniweyo se-0.2% ye-methylene blue, zombini zikwi-95% ye-ethanol. Le ndlela iyalela umhlalutyi ukuba athelekise indawo yokuphela nesampulu engenayo into ehlalutywayo, enemithamo ehambelanayo yamanzi neasidi yeboron.
Le ndlela yokulungiselela nomxube othengiswayo okhankanywe ngasentla zinomlinganiselo ofanayo wobunzima bedayi, kodwa zinoxinzelelo olwahlukileyo nokwakheka okwahlukileyo kwezinyibilikisi. Ngoko umlinganiselo ofanayo awubobungqina obaneleyo bokuba iibhotile ezimbini zingasetyenziswa endaweni enye kwenye. Le nkqubo ikwajolise kwinitrogen ekwiammonia kwaye iyikhuphela ngaphandle ngokucacileyo initrogen iyonke ye-Kjeldahl kummandla wayo. Ukusebenzisa isalathisi esifanayo akwenzi iindlela ezimbini zokulinganisa initrogen zibe luvavanyo olunye.
Sebenzisa olo xwebhu ukuze uqonde inkqubo yohlalutyo echaziweyo, kunokuba ucinge ukuba uhlelo lwayo lwakudala lulawula imfuneko yangoku yokunika ingxelo. Indlela eyamkelweyo yilabhoratri kufuneka ichaze uhlelo olusebenzayo kunye nolawulo lwalo lomgangatho.
Indawo yokuphela nendawo yokulingana ngokwekhemikhali zahlukile
I-IUPAC ichaza ititration nendawo yayo yokuphela ngokunxulumene nokubona ukuba intsabelano igqityiwe; indawo yokulingana ngokwekhemikhali ihambelana nokulingana okuchanekileyo kwemichiza. Umqondiso obonakalayo uluncedo xa usondele ngokwaneleyo kuloo ndawo ngokwenjongo yendlela esetyenziswayo.
Masithi abahlalutyi ababini benza ititration kwiisampulu ezifanayo. Omnye uyeka xa isisombululo sifana nesampulu echaziweyo engenayo into ehlalutywayo. Omnye uyaqhubeka de kubonakale owona mbala umfusa unzulu. Umhlalutyi wesibini ukhethe indawo yokuphela eyahlukileyo kwaye unokusebenzisa i-titrant egqithisileyo. Ukuvumelana ngegama lombala wokugqibela akuqinisekisi ukuvumelana ngobungakanani obulinganisiweyo.
Yiloo nto isikhokelo soqeqesho kufuneka sichaze into yokuthelekisa, iimeko zokujonga, kunye nomqathango wexesha umqondiso omele uhlale ngalo, ngokweemfuno zendlela. Umfanekiso okwisikrini unokuchaza indlela yotshintsho, kodwa into yokuthelekisa eselabhoratri yiyo emisela isigqibo ngexesha lomsebenzi.
Uvavanyo olusebenzayo ngaphambi kokutshintsha isalathisi okanye ukuphanda ingxaki yaso
Sebenzisa eli phepha lomsebenzi xa umbala ubonakala ungalunganga okanye kucetyiswa ibhotile yokuthatha indawo yenye:
| Into yokuhlola | Okubhaliweyo | Isizathu sokuchaphazela kwayo ukutolika |
|---|---|---|
| Ubuni berejenti | Omabini amagama edayi nekhowudi yemveliso | Isalathisi esixutyiweyo esinegama elifanayo sinokuba neekhemikhali ezahlukileyo |
| Umxube | Uxinzelelo lweedayi, umlinganiselo, nesinyibilikisi | Umlinganiselo wodwa ushiya umahluko obalulekileyo ungacaciswanga |
| Inkqubo | Indlela, uhlelo, ukongezwa kwesalathisi, nendlela ehamba ngayo ititration | Inkcazelo yebhotile ayiluchazi lonke uhlalutyo |
| Into yokuthelekisa kwindawo yokuphela | Isampulu efunekayo engenayo into ehlalutywayo okanye enye into yokuthelekisa, nomgaqo wokuyeka | “Mfusa” unokuchaza iinkangeleko ezininzi ezahlukileyo emehlweni |
| Ukuziphatha okungalindelekanga | Ukuba utshintsho lulandela ukongezwa kwe-titrant, ukuyekwa ime, okanye ukungeniswa komoya | Umjikelo wokuphela kombala oxhomekeke kwixesha ufuna uphando olungaphaya kwe-pH |
Thatha ukungaphumeleli kwesampulu engenayo into ehlalutywayo okanye utshintsho lombala olungachazekiyo njengesizathu sokuphanda irejenti nendlela ngaphambi kokunika ingxelo yeziphumo. Ukongeza idayi engakumbi de isampulu ibonakale ngendlela eqhelekileyo kuguqula iimeko zokujonga kwaye kunokuyifihla ingxaki yokuqala.
Xa ukhetha indima efanelekileyo yedayi kolunye uvavanyo, qala nge-methylene blue kuvavanyo lohlalutyo. Kwiititration ze-Tashiro, gcina indlela owenziwe ngayo umxube wedayi, indawo yokuphela ebonakalayo, nokubalwa kweziphumo zohlalutyo kubhaliwe kunye.