Mokhoa oa Tlhahlobo ea Molumo
Tlhahlobo ea volumetric ke mokhoa oa bohlokoa k'hemistring ea tlhahlobo, o sebelisoang ho fumana hore na ntho e na le bokae ka ho lekanya bophahamo ba tharollo ea reactant e hlokahalang ho fihlela ntlha ea ho lekana. Mokhoa ona o na le mefuta e mengata ea ts'ebeliso, ho tloha tlhahlobong ea boleng ba metsi le tlhahlobo ea lijo ho isa maemong a metsoako e sebetsang meriana, ho isa taolong ea boleng ba indasteri. Hobane e itšetlehile ka litekanyo tse bonolo tsa volumetric, tlhahlobo ea volumetric ke mokhoa o sebetsang hantle, o theko e tlaase le o nepahetseng ha o etsoa hantle.
Tlhaloso le Melao-motheo ea Motheo
Tlhahlobo ea volumetric (titrimetry) ke mokhoa oa bongata o lekanyang bophahamo ba tharollo e tloaelehileng (titrant) e arabelang ka mokhoa o sa fetoheng le ntho e hlahlojoang (analyte). Karabelo pakeng tsa titrant le analyte e tsoela pele ho fihlela boemo ba ho lekana bo fihletsoe, ke hore, ha palo ea li-moles tsa titrant tse arabelang e lekana hantle le palo ea li-moles tsa analyte ho latela equation ea karabelo.
Melao-motheo ea mantlha ea li-volumetric e kenyelletsa:
1. Karabelo e lokela ho ba e tobileng mme e etsahale ka ho phethahetseng (kapa hoo e ka bang ka ho phethahetseng).
2. Stoichiometry ea karabelo e tlameha ho tsejoa ka ho hlaka e le hore lipalo tsa mahloriso li ka etsoa.
3. Ntlha ea ho qetela ea titration e tlameha ho fumanoa ka nepo, hangata ka sesupo kapa sesebelisoa sa ho lekanya (mohlala, mithara ea pH).
4. Tharollo e tloaelehileng e tlameha ho ba le mahloriso a tsejoang ka nepo, e le hore bophahamo bo sebelisitsoeng bo ka fetoloa hore e be bongata ba ntho.
Likarolo tsa Bohlokoa Tlhahlobong ea Molumo
E le hore tlhahlobo ea volumetric e hlahise data e nepahetseng, likarolo tse latelang li lokela ho nahanoa:
1. Tharollo e Tloaelehileng (Titrant)
Tharollo e tloaelehileng ke tharollo e nang le mahloriso a tsebahalang. Ho na le mefuta e 'meli:
– Litekanyetso tsa mantlha, e leng dintho tse hlwekileng tse nang le motswako o tsitsitseng mme di ka lekanngwa ka nepo ho etsa ditharollo tse nang le mahloriso a nepahetseng (mohlala, Na2CO3, K2Cr2O7, di-oxalic acid tse itseng).
– Tekanyetso ea bobeli, e leng tharollo eo mahloriso a eona a fumanoang ka ho lekanngoa khahlanong le tekanyetso ea mantlha (mohlala, HCl, NaOH, KMnO4 tlas'a maemo a itseng).
2. Mohlahlobi
Mohlahlobi ke ntho eo mahloriso a yona a lokelang ho lekanyetswa. E ka ba asiti, motheo, ioni ya tshepe, moemedi wa oxidizing kapa wa ho fokotsa, kapa ntho efe kapa efe, ha feela e arabela le titrant ka tsela e ka lekanngwang.
3. Lipontšo le Mekhoa ea ho Fumana Qetello ea Ntlha
Ntlha ea qetello ke letšoao leo titration e emisitseng ho lona. Tsela e tloaelehileng ea ho e fumana ke:
– Ditshupo tsa mmala, tse kang phenolphthalein, methyl lamunu, methyl red.
– Potentiometry, ho beha leihlo liphetoho tse etsahalang ka matla a motlakase kapa pH.
– Conductometry, e lekanyang diphetoho tsa conductivity ya motlakase.
– Pheletso ya Turbidimetry/Placipitation, e lekola ho thehwa ha sediment.
Khetho ea sesupo e bohlokoa haholo hobane phetoho ea 'mala ea sesupo e lokela ho etsahala haufi kamoo ho ka khonehang le ntlha ea ho lekana.
4. Lisebelisoa tsa Bophahamo
Lisebelisoa tsa khalase tse sebelisoang hangata li kenyelletsa:
– Burette, ho rotha titrant ka ho nepahala ho hoholo.
– Pipette ea volumetric, ho nka bophahamo bo nepahetseng ba analyte.
– Ho lekanya flaske, ho lokisa ditharollo tse tlwaelehileng ka bophahamo bo itseng.
– Erlenmeyer, e le setshelo sa karabelo ya titration.
Ho nepahala ha ho baloa ha meniscus, bohloeki ba lisebelisoa, le mokhoa oa ho lekanya (mohlala, ho theoha butle ho ea qetellong) ke lintlha tse khethollang boleng ba liphetho.
Mefuta ea Tlhahlobo ea Molumo
Tlhahlobo ea volumetric e ka aroloa ka lihlopha ho latela mofuta oa karabelo e hlahang.
1. Titration ea Asiti-Base
Titration ea motheo oa asiti ke eona e atileng haholo. Molao-motheo ona o ipapisitse le karabelo ea neutralization lipakeng tsa asiti le motheo. Mehlala ea lits'ebetso:
– Fumana hore na HCl e na le bokae ka NaOH titrant.
– Fumana boemo ba asiti ea asetiki ka har'a asene.
– Ho lekanya alkalinity ea metsi.
Titration ena e hloka kutloisiso ea matla a asiti/base (a matla kapa a fokolang) hobane e ama mothapo oa titration le khetho ea sesupo. Phenolphthalein, mohlala, e loketse li-titration tse fokolang tsa asiti-strong base, ha methyl orange e atisa ho sebelisoa bakeng sa li-titration tse matla tsa asiti-bofokoli, ho latela maemo.
2. Redox Titration (Ho Fokotsa Oxidation)
Li-titrations tsa Redox li kenyelletsa phetiso ea lielektrone. Titrant e sebetsa e le moemeli oa oxidizing kapa oa fokotsang. Mehlala e tloaelehileng e kenyelletsa:
– Permanganometry e sebelisa KMnO4 e le sesebelisoa se matla sa oxidizing. KMnO4 e boetse e sebelisoa hangata e le sesupo ka lebaka la 'mala oa eona.
– Iodometry/Iodimetry e sebedisa iodine kapa thiosulfate ho fumana maemo a di-oxidizer kapa di-reducer.
– Dichromatometry e sebelisang K2Cr2O7 e le oxidizer.
Redox titration e sebediswa haholo bakeng sa ho sekaseka maemo a dintho tse kang Fe(II), vithamine C, chlorine e se nang chlorine, esita le dikahare tsa thepa ya oxidizing ya indasteri.
3. Pula e nang le Titration
Titration ea pula e etsahala ha titrant e arabela le analyte ho theha precipitate e sa qhibiliheng hantle. Mohlala oa khale ke titration ea argentometric, ho sebelisoa AgNO3 ho fumana halides (Cl⁻, Br⁻, I⁻). Mokhoa oa argentometric o na le mefuta e fapaneng:
– Mohr, ho sebelisoa sesupo sa chromate.
– Volhard, a sebelisa back titration e nang le thiocyanate.
– Fajans, ho sebelisoa litsupa tsa ho monya metsi.
Mofuta ona oa titration o thusa ho fumana hore na letsoai le bokae (mohlala, chloride ka metsing) le ho sekaseka li-anion tse itseng.
4. Titration e rarahaneng
Titration e rarahaneng e kenyelletsa ho thehoa ha motsoako o tsitsitseng pakeng tsa ion ea tšepe le ligand. Reagent e tsebahalang haholo ke EDTA (Ethylenediaminetetraacetic acid). Mokhoa ona o sebelisetsoa ho:
– Fumana bothata ba metsi (Ca²⁺ le Mg²⁺).
– Tlhahlobo ea litšepe litharollong tsa indasteri.
– Ho fumana li-ion tsa tšepe lisampoleng tsa tikoloho.
Lipontšo tse rarahaneng (mohlala, Eriochrome Black T) li thusa ho bontša liphetoho ha EDTA e tlama ion ea tšepe ka botlalo.
Mehato e Akaretsang ea Ts'ebetso ea Titration
Leha mofuta o mong le o mong oa titration o na le lintlha tse fapaneng, phallo e akaretsang ea tlhahlobo ea volumetric hangata e kenyelletsa:
1. Ho lokisa tharollo e tloaelehileng (kapa ho etsa hore titrant e be boemong bo tloaelehileng haeba ho hlokahala).
2. Ho nka sampole e nepahetseng ea li-analyte ho sebelisoa pipette ea volumetric.
3. Ho eketsa ditshupa-tsela kapa ho kenya disebediswa tsa ho lekanya (dimithara tsa pH).
4. Titration: titrant e rotha ho tsoa ho burette ha e ntse e hlohlelletsa ho fihlela e atamela ntlha ea ho qetela.
5. Tlhokomelo ea ntlha ea qetello: phetoho e tsitsitseng ea 'mala kapa boleng ba sesebelisoa sa ho lekanya bo fihla boemong bo itseng.
6. Ngola bophahamo ba titrant e sebelisitsoeng 'me u bale mahloriso a analyte ho latela stoichiometry.
Ho pheta-pheta ha di-titrations (hangata bonyane makgetlo a mabedi ho isa ho a mararo) hoa hlokahala ho netefatsa hore di-titrations di ka ikatisa hape, mme diphetho di fapana hanyane feela.
Lipalo tsa Tlhahlobo ea Molumo
Lipalo tsa mahloriso a analyte hangata li sebelisa likhopolo tsa li-mole le stoichiometry. Ka mantsoe a bonolo, palo ea li-mole tsa titrant tse arabelang ke:
\[
n = M \makhetlo V
\]
ka \(n\) = li-moles, \(M\) = molarity, \(V\) = bophahamo ba modumo (L). Ka mor'a moo, li-moles tsa analyte li fumanoa ho latela karolelano ea li-coefficients tsa karabelo. Ho tsoa li-moles tsa analyte, mahloriso, boima, kapa peresente ea sampole e ka baloa.
Melemo le Meeli
Boemo bo phahameng
– E potlakile ebile e theko e tlase haholo ha e bapisoa le lisebelisoa tse rarahaneng.
– Ho nepahala ho hoholo haholo haeba titrant e lekantsoe hantle.
– Mokhoa o bonolo mme o ka sebelisoa mefuteng e fapaneng ea lisampole.
– E loketse tlhahlobo ea kamehla ea taolo ea boleng.
Meeli
– E hloka karabelo e hlakileng le ntlha ea qetello e bonahalang habonolo.
– Disampole tse ding tse nang le maru di ka etsa hore ho be thata ho sebedisa sesupo.
– Liphoso tse nyane ho baleng ha mahalatte kapa ho fumana ntlha ea ho qetela li ka ama liphetho.
– Ha se kamehla ho loketseng bakeng sa mahloriso a tlase haholo a di-analyte ntle le mekgwa e meng.
Ho koala
Mekhoa ea tlhahlobo ea volumetric ke motheo oa bohlokoa k'hemistring ea tlhahlobo hobane e kopanya melao-motheo ea stoichiometric le litekanyo tse nepahetseng tsa bophahamo. Ka mekhoa e fapaneng ea titration—acid-base, redox, precipitation, le complexometry—tlhahlobo ea volumetric e ka fihlela litlhoko tsa tlhahlobo tsa lilaboratori tsa thuto le tsa indasteri. Senotlolo sa katleho se ho khethoeng karabelo e nepahetseng, ho leka-lekanya tharollo, ho sebelisa lisebelisoa tsa volumetric ka hloko, le ho fumana pheletso ka nepo. Ka ts'ebeliso e nepahetseng ea lits'ebetso, tlhahlobo ea volumetric e ntse e le mokhoa o tšepahalang oa ho fumana ka bongata mahloriso a lintho lits'ebetsong tse fapaneng.
