Synthesis of Potassium Iodate

Synthesis of Potassium Iodate

Scientific name: The oxidation of iodine and reduction of Cl(V)


Synthesis of Potassium Iodate

by hkparker


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Reaction formula

5 KClO3 + 3 I2 + 3 H2O → 6 HIO3 + 5 KCl

HIO3 + KOH → KIO3 + H2O

Step-by-step instruction

WARNING! This experiment is dangerous! You should NOT perform this at home. ONLY carry out this experiment, if you are a trained chemist, and you understand local safety and legal requirements, which are required to perform such experiments

  1. Dissolve a small amount of potassium chlorate in water, using a flat-bottomed flask.
  2. Add several drops of concentrated nitric acid so that the pH of the solution becomes about two.
  3. Add a small amount of iodine.
  4. Heat the flask until all iodine dissolves, using a spirit lamp.
  5. Add a small amount of potassium hydroxide until the medium becomes basic.
  6. Filter the resulting mixture.
  7. Evaporate half of the water from the filtrate.
  8. Place the cup with the solution in a refrigerator.
  9. The white precipitate should fall. Decant the yellow solution above the precipitate.
  10. The resulting precipitate is potassium iodate.

Scientific background

There is a redox reaction. The reduction potential of the oxidizing agent is greater than the reduction potential of the reducing agent, so this process is possible. In addition, a plurality of side reactions occurs with the release of chlorine and nitrogen oxides, which explains the formation of precipitate in the first stage and the yellowing of the solution.

The second stage is a common neutralization reaction.

Potassium iodate has a lower solubility than impurities, and therefore can be isolated by crystallization from a cold solution.


Published on 13 June 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst