O’zbekiston Respublikasi Oliy va o’rta maxsusta

2Na₂S₂O₃ + J₂ = 2NaJ + Na₂S₄O₆
Bu reaksiya pH – qiymati 7 – 6 atrofida bo‘lganda sodir bo‘ladi. pH – qiymati o‘zgarsa, reaksiya boshqacharoq kechadi. Shu muhitni ta’minlash uchun NaHCO₃ qo‘shiladi.
Aralashmadan analizga olish vaqti tajribaning boshlanish vaqti hisoblanadi va sekundomer yurgiziladi. Reaksiyaning borishini ma’lum vaqtlardan so‘ng reaksion aralashmadagi yodning konsentratsiyasini yukorida aytilgan usul bilan (Na₂S₂O₃ bilan titrlab) aniqlash orqali kuzatiladi/
Reaksiyaga kirishgan atseton konsentratsiyasi quyidagi tenglama asosida
hisoblanadi:
eritmasining birinchi titrlashga sarf bo‘lgan hajmi (t=0da), ml.
eritmasining ma’lum vaqtdan so‘ng titrlashga sarf bo‘lgan hajmi, ml.
eritmasining normal konsentratsiyasi, mol/l
Tajriba natijalari jadvalga yoziladi. Bu ma’lumotlarni (I) tenglamaga qo‘yib «K» hisoblanadi.
17.8-jadval

Vaqt, Мinutda	Titrlashga sarf bo‘lgan Na2S2O3eritmasining hamji, ml	Сx g-ekv/l	С^0ats g-ekv/l	С^0Н^+ g-ekv/l	Tezlik konstantasi, K
0				0,1
15				0,1
30				0,1
45				0,1

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Nazorat Savollari

1. Potensiometrik titrlash usuli nimaga asoslangan?

2. Kalomel elektrodining tuzilishi qanday?
3. Veston elementining tuzilishini yozing.
4. Xingidron elektrodining tuzulishini tushuntiring.
5. Daniel-Yakobi elementining zanjirini yozing.
6. Alohida elektrodlarning potensiallari qanday aniqlanadi?
7. Shartli elektrod potensiali deb nimaga aytiladi?
8. Galvanik elementlarning EYuKni o’lchayotganda Veston elementi qanday ro’l o’ynaydi?
9. O’z tuzining eritmasiga tushirilgan metallning sirtida musbat zaryad hosil bo’lishining termodinamik sharti qanday?
10. EYuK ning qiymati standart elektrod potensiallarining qiymatlariga bog’liq bo’lmagan galvanik elementlar mavjudmi?
11. Galvanik elementning EYuKni voltmetr yordamida o’lchasa bo’ladimi? Javobni izohlang.
12. Standart EYuK deb nimaga aytiladi?
13. Galvanik elementning EYuKsi haroratga bog„liq bo„lmaganda uning ichki energiyasi o’zgaradimi? Javobni izohlang.
14. Galvanik element bajargan elektr ishini hisoblash uchun qanday konstantalarni va tajribaviy ma’lumotlarni bilish kerak?
15. Veston elementi elementlarning qanday turiga tegishli (konsentratsion, kimyoviy, tashish bo’lmagan, tashishli)?