Noorganik kimyo kafedrasi analitik kimyo laboratoriya ishlanmalar

Titrlash egri chizig'i

Aniqlanishi kerak bo'lgan modda kaliy bixromatdir

Titrant K₄[Fe(CN)₆] eritmasidir.
Fon - 0,5 M Na₂SO₄.
Usulning mohiyati.
Kimyoviy reaksiya. Kuchli kislotali muhitda geksatsianoferrat (II) - ionlari kaliy dixromat bilan geksasianoferrat (III) - ionlarigacha oksidlanadi:
Cr₂O₇^2- + [Fe(CN)₆]^4- + 14 H⁺ → [Fe(CN)₆]^3- + 2Cr³⁺ +7H₂O

Elektrokimyoviy reaktsiya ferrosiyanid (II) ionlarining oksidlanishi tufayli Faraday komponenti tufayli ekvivalent nuqtaga yetgandan so'ng qayd etilgan oqimning oshishiga olib keladi:

Ishchi elektrodning potentsiali to'g'ri tanlangan bo'lsa, Fe (II) oksidlanish oqimi uning eritmadagi konsentratsiyasiga to'g'ridan-to'g'ri proportsionaldir.

Reaktivlar. 1. Fon elektrolit eritmasi (2M).
2. Namuna eritmasi (100 ml li kolbada).
3. Titrant eritmasi (0,03M).
4. Distillangan suv.


Aniqlash usuli.

1. Hujayrani distillangan suv bilan yuvib bo‘lgach, unga silindr bilan 10 ml fon va pipetka bilan 10 ml namuna eritmasidan quying.

2. Potensiostatni yoqing. Titrlash potentsialini o'rnating.
3. Oqim o'rnatilgandan so'ng, uning qiymatini jadvalga kiriting.
4. 0,05 ml titrant qo'shing.
5. 3 va 4-bosqichlarni navbat bilan almashtiring.
6. Titrlash egri chiziqning ikkinchi kesimida (ekvivalentlik nuqtasidan keyin) 4-5 ta eksperimental nuqta olingandan keyin yakunlanadi.
7. Ekvivalent nuqtani topish uchun ikkita tangens usulidan foydalanib, hosil bo'lgan egri chiziqni grafik qog'ozga ko'rsating.
8. Kaliy bixromatning tarkibini hisoblang:

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Hulosa ____________________________________________________________ __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
№6. Laboratoriya ishi
Pоlyarоgrаfik аnаliz mеtоdi.
Аrаlаshmаdаgi mеtаllаrni sifаt vа miqdоriy аniqlаsh