Redox Titrations
Redox principle
At equivalence, transferred electrons are equal on both sides.
nOx × e⁻Ox = nRed × e⁻Red
- Permanganate titration (KMnO₄)
- Iodometry / iodimetry
- Electron balance instead of proton balance
Formulas
nOx × eOx = nRed × eRed
nRed = (nOx × eOx) / eRed
nOx = (nRed × eRed) / eOx
Examples
KMnO₄ vs Fe²⁺
nOx=0.002; eOx=5; eRed=1
nRed=0.010 mol
nOx=0.002; eOx=5; eRed=1
nRed=0.010 mol
Iodometry
I₂ + 2 e⁻ → 2 I⁻
use correct eOx/eRed values
I₂ + 2 e⁻ → 2 I⁻
use correct eOx/eRed values
Equivalence point
Left and right electron amounts are equal.
Left and right electron amounts are equal.
Practice
Always start with a balanced redox equation.
Always start with a balanced redox equation.
Technical Background
KMnO₄ titrations
Permanganate is a strong oxidizer; in acidic media it accepts 5 electrons.
Iodine titrations
Iodine/iodide systems often involve 2-electron steps and are widely used in analytical chemistry.
|
|
|
|