Elektrodlardagi jarayonlar. Oksidlanish-qaytarilish potensiallari

Rux - mis galvanik elementi

• _ +
• Zn Cu
• CuSO4 + Zn = ZnSO4 + Cu

• CuSO4

• ZnSO4

• G

• Zn2+

• Cu2+

• SO42-

Har qanday oksidlanish - qaytarilish potensiallarining ayirmasi elektr.yurituvchu kuch E.Yu.K ni beradi: Ex = E2 - E1 ; V

• Oksidlanish - qaytarilish potensiallari hosil bo`ladigan sistemalar:
• PtFeCl3FeCl2; PtSnCl4SnCl2
• Pt MnO4-  Mn2+; Pt Cr2O72- Cr3+
• Pt K3[Fe(CN)6]  K4[Fe(CN)6]

Peters tenglamasi

• RT oksidlangan
• Ered = E0red+ ------- l n ---------------------
• nF qaytarilgan
• E - oksidlanish - qaytarilish potensiali
• E0 - standart oksidlanish - qaytarilish potensiali
• R - universal gaz doimiysi; T - absolut harorat
• F - Faradey soni, n -elektronlar soni
• oksidlangan - oksidlangan modda konsentrat-si
• qaytarilgan - qaytarilgan modda konsentrat-si

Peters tenglamasi

• 0,058 oksidlangan
• Ered = E0red+ ------- l g ---------------------
• n qaytarilgan
• oksidlangan= qaytarilgan; Ered = E0red
• Murakkab oksidlanish - qaytarilish sistemalar uchun:
• 0,058 oksidlangan[H+]
• Ered = E0red+ ------- l g ------------------------
• n qaytarilgan

Red-Ox potensiallarni o`lchash

• O`lchovchi elektrodlar:
• Pt, Ir, Pd - E.Yu.K uchun
• Pt/ HG/H+, shisha elektrodi - pH uchun
• Solishtirish elektrodlari:
• Ag/AgCl/KCl (to`yingan) -kumush hloridli elektrod (e = 0,201 V),
• Hg/Hg2Cl2/ KCl (to`yingan) -kalomelli elektrod
• (e = 0,246 V).

Shisha elektrodining tuzilishi

• Ag/AgCl

• Shisha membrana

• 0,1 M HCl

• Shisha elektrod

• Cu

Galvanik element shemasi

• Pt K3[Fe(CN)6] AgCl; Ag
• K4[Fe(CN)6] KCl
• (to`yingan)
• Ag AgCl;HCl shisha aniql-gan AgCl; Ag
• [H+]=const memb- eritma KCl
• rana [H+]=x (to`ying.)

Potensiometrik titrlash egri chiziqlari

• HCl + NaOH = NaCl + H2O

• VNaOH

• pH

• VNaOH

• VNaOH

• E

• pH

• Integral chizma

• HCl + NaOH = NaCl + H2O

Potensiometrik titrlash egri chiziqlari

• VNaOH

• ΔpH
• Δ(E)

• E.n.

• NNaOH·VNaOH NHCl = --------------- VHCl

• Diferensial chizma