MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
Potassium permanganate titration. At the start of a redox titration between oxalic acid and potassium permanganate the solution of oxalic acid is clear. If the solution turns brown during the titration the acid needs to be reactivated by warming the solution to 85 degrees Celsius or by adding sulphuric acid - the solution will then clear. Potassium permanganate is added until the end point is observed, when the solution turns a pale pink.
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