A suspension of 165 g. of Bi2O3 in 1.5 liters of 50% potassium
hydroxide is oxidized at the boiling point (as described above for NaBiO3) with small portions of Br2 (total 500 g.). A dark violet
precipitate results. Now, an additional 500 ml. of hot 40% potassium
hydroxide is added and the material is filtered after settling. The
precipitate is washed with 40% potassium hydroxide, suspended in
3-5 liters of H2O, and agitated for a while. The liquid is decanted
after some hours; the solid is washed with cold H2O and filtered.
The bright red precipitate is dried over H2SO4 in a desiccator.
The yield is 205 g. of KBiO3 ? 1/3 H2O. Formula weight (anhydrous) 296.1.
Bi2O3 +
6KOH + 2Br2
= 2 KBiO3 + 4KBr + 3H2O.
