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Combustion of potassium chlorate and sugar. (Skatebiker)Potassium chlorate (KClO3) is one of the most useful potassium compounds you can keep around the chem lab. It can be used as an oxidizer and disinfectant and to make pyrotechnics, safety matches, and to prepare oxygen gas. You can prepare potassium chlorate from common household chlorine bleach and salt substitute. The reaction is not particularly efficient, but it's something to keep in mind if you need potassium chlorate right away or just want to know how to make it.

Materials for Making Potassium Chlorate

  • chlorine bleach
  • potassium chloride (sold as a salt substitute)
  • filter paper or coffee filter

Prepare Potassium Chlorate

  1. Boil a large volume (at least a half liter) of chlorine bleach, just until crystals start to form. Do this outdoors or under a fume hood, to avoid inhaling the vapor. Boiling bleach disproportionates sodium hypochlorite into sodium chloride and sodium chlorate.

    3 NaClO → 2NaCl + NaClO3

  2. As soon as crystals start to form, remove the bleach from heat and allow it to cool.

  3. In a separate container, prepare a saturated solution of potassium chloride by stirring potassium chloride into water until no more will dissolve.

  4. Mix equal volumes of the boiled bleach solution and potassium chloride solution, taking care to keep solids from either solution out of the mixture. Potassium chlorate will precipitate out, leaving sodium chloride in solution.

    KCl + NaClO3 → NaCl + KClO3

  5. Cool the solution in the freezer to increase the potassium chlorate yield.

  6. Filter the mixture through filter paper or a coffee filter. Keep the solid potassium chloride; discard the sodium chloride solution.

  7. Allow the potassium chlorate to dry before storing or using it. NurdRage has a video of the process, if you'd prefer to see how it's done.
You can test the potassium chlorate in a simple chemistry demonstration:
  • Purple Fire (shown) - Mix potassium chlorate and half as much sugar. Ignite the mixture either by applying a flame or adding a few drops of sulfuric acid (instant chemical fire).

  • Dancing Gummi Bear - The candy is the source of the sugar in this demonstration. The vigorous reaction between the candy bear and the potassium chlorate makes the bear appear to dance in purple fire.


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