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How To Make Potassium Nitrate

Make Potassium Nitrate from Lite Salt and a Cold Pack

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This homemade smoke bomb is made using potassium nitrate and sugar.

This homemade smoke bomb is made using potassium nitrate and sugar.

Anne Helmenstine

Make potassium nitrate (saltpeter) from common household ingredients. Potassium chloride from lite salt and ammonium nitrate from a cold pack are reacted to yield potassium nitrate and ammonium chloride. This is an easy way to make your own potassium chloride if you can't find it in a store or just want to try a fun chemistry experiment.

Potassium Nitrate Ingredients

  • 40 g ammonium nitrate (from an instant cold pack which has ammonium nitrate listed as its ingredient)

     

  • 37 g potassium chloride (sold as a salt substitute, with potassium chloride listed as the ingredient)

     

  • 100 ml water

The Chemical Reaction

Aqueous solutions of ammonium nitrate and potassium chloride are reacted to exchange the ions and form potassium nitrate and ammonium chloride. The ammonium chloride is much more soluble in water than the potassium nitrate, so you will get potassium nitrate crystals, which can be separated from the ammonium chloride solution.

NH4NO3 + KCl → KNO3 + NH4Cl

Make Potassium Nitrate

  1. Dissolve 40 g of ammonium nitrate into 100 ml of water.

     

  2. Filter the solution through a coffee filter to remove any undissolved material.

     

  3. Heat the solution with 37 g potassium chloride to dissolve the lite salt. Do not boil the solution.

     

  4. Filter the solution and either set it in the freezer to chill or else put it in an ice bath so you can observe the crystallization of the potassium nitrate.

     

  5. Pour off the ammonium chloride solution, leaving the potassium nitrate crystals. You can recover the ammonium chloride, too, if you like.

     

  6. Once the potassium nitrate crystals are dry, you can use them for chemistry experiments. The resulting potassium nitrate does contain impurities, but it will work fine for pyrotechnics projects and other experiments described on this site.

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