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POTENSIOMETRI

POTENSIOMETRI. Edi Nasra, S.Si., M.Si. SEL VOLTA. Potensial Sel. Example 1 : What are the anodic, cathodic and overall reactions responsible for the potensial in the elecrochemical cell shown here? Write the shorthand notation for the electrochemical cell.

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POTENSIOMETRI

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  1. POTENSIOMETRI Edi Nasra, S.Si., M.Si

  2. SEL VOLTA

  3. PotensialSel

  4. Example 1: What are the anodic, cathodic and overall reactions responsible for the potensial in the elecrochemical cell shown here? Write the shorthand notation for the electrochemical cell

  5. Example 2: what is the potential of the electrochemical cell shown in example 1 (Eo Fe3+/Fe2+ = +0.771 V ; Eo AgCl/Ag = +0.2223 V

  6. Example 3: what is the concentration of Fe3+ in an electrochemical cell similar to that shown in example 1 if concentration of HCl in the left-hand cell is 1.0 M, the concentration of FeCl2 in the right-hand cell is 0.0151 M and the measured potential is +0.546 V

  7. 84,2 mV Refrence ElectrodesEref Salt Bridge, Ej Indicator ElectrodesEind Potentiometric Cells Esel=Eind – Eref+ Elj

  8. Liquid Junction Potentials

  9. Elektroda Pembanding  Elektroda yang mempunyai harga potensial tetap dan konstan dan tidak dipengaruhi konsentrasi analit dalam larutan

  10. ElektrodaHidrogenStandar

  11. ElektrodaKalomel • Besarnya potensial sel: • jika digunakan KCl jenuh + 0.2440 V • jika [KCl] 3.5 M maka E = +0.2500 V • jika [KCl] 0.1 M maka E = +0.3356 V

  12. Elektroda Ag/AgCl • Besarnya potensial: • jika digunakan KCl jenuh E = 0.199 V • jika digunakan KCl 3.5 M maka E = 0.205 V

  13. Elektroda Indikator  Elektroda yang potensialnya bergantung pada konsentrasi zat yang sedang diselidiki

  14. Elektroda Kerja Logam • Elektroda Jenis Pertama Logam yang dicelupkan kedalam larutan ionnya Contoh: logam tembaga yang dicelupkan ke dalam larutan ion Cu2+

  15. Elektroda Jenis Pertama

  16. Elektroda Jenis Kedua Elektroda logam yang dicelupkan ke dalam larutan yang dijenuhkan dengan garam sukar larut dari ion logam tersebut.

  17. Elektroda Jenis Kedua

  18. Example 4: Calculate the formation constant Kf for Ag(CN)2- if the cell: SCE || Ag(CN)2- (7.50 x 10-3 M, CN- (0.0250 M)| Ag develops a potential of -0,625 V

  19. Elektroda Redoks Elektroda logam inert dicelupkan ke dalam larutan yang mengandung ion yang dapat mengalami reaksi reduksi/oksidasi di permukaan elektroda tersebut. Elektroda ini tidak terlibat dalam reaksi tersebut. Contoh: Fe3+, Fe2+Pt

  20. Elektroda Membran

  21. SelektifitasMembran [A]E dan [I]E adalah konsentrasi analit dan pengganggu yang memberikan nilai potensial sel yang sama

  22. Penentuan Tetapan Selektifitas

  23. Elektroda Gelas

  24. Mekanisme Timbulnya Potensial H+(lar.) + Na+Gl-(mem.)  Na+(lar.) + H+Gl-(mem.)

  25. Membran Larutan Batas Membran-Larutan Mekanisme Timbulnya Potensial H+Gl-(mem.)  H+(lar.) + Gl-(mem.)

  26. ESI Kalsium

  27. Aktivitas vs Konsentrasi Jika  tetap

  28. Ionic Strength Adjuster Kekuatan Ion () Debeye-Huckel =diameter efektif ion

  29. AnalisisKuantitatif • Method of external standards What is the concentration of Ca2+ in the water sample if its cell potential is found to be -0.084 V?

  30. Quantitative Analysis • Method ofStandard Additions Contoh: The concentration of Ca2+ in a sample of sea water is determinedusing a Ca ion selective and a one point standard addition. A 10.00 mL sample is transferred to a 100 mL volumetric flask and diluted to volume. A 50.00 mL aliquot of sample is placed in a beaker with the Ca ion-selective electrode and a reference electrode, and the potential is measured as -0.05290 V. A 1.00 mL aliquot of a 5.00 x 10-2 M standard solution of Ca2+ is added, and a potential of -0.04417 V is measured. What is the concentration of Ca in the sample of sea water?

  31. TitrasiPotensiometri • Elektrodakerjadanelektrodapembandingdicelupkankedalamlarutananalit. • Potensialseldiamatiselamapenambahantitran. • Titikakhirditentukandarikurvatitrasi

  32. Titrasi Potensiometri

  33. The titration curve

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