← Oxidation-reduction processes
6 Electrolysis & redox titrations
Electrolysis
- A power supply forces a non-spontaneous redox reaction.
- Cathode (−): reduction (cations gain electrons). Anode (+): oxidation.
- In aqueous solutions, water may be preferentially discharged: compare E° values.
Redox titrations
- Self-indicating example: MnO₄⁻ is purple → colourless Mn²⁺; the endpoint is the first permanent pink.
- Use the mole ratio from the combined redox equation to relate titre to concentration.
- Iodine/thiosulfate titrations use starch indicator (blue-black → colourless at the endpoint).