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Fireworks season is coming up, so before I get into the new fireworks projects, I wanted to cover the synthesis of a common chemical used for pyrotechnics: ammonium nitrate. Another fun project to try with ammonium nitrate is to make an endothermic reaction. You can buy ammonium nitrate as a pure chemical or you can collect it from instant cold packs or some fertilizers. You can make ammonium nitrate by reacting nitric acid with ammonia, but if you don't have access to nitric acid (or don't want to mess with it), you can make ammonium nitrate from readily available home chemicals.

Ammonium Nitrate Chemicals

You will need:
  • 138 g sodium bisulfate (found with pool chemicals, used to lower pH)
  • 1 mole equivalent of a nitrate salt... any of the following
  • ammonia (common household cleaner)
  • methanol (optional, which may be found as HEET fuel treatment)

Prepare Ammonium Nitrate

  1. Dissolve the sodium bisulfate in the mininum amount of water (about 300 ml).

  2. Dissolve your nitrate salt in the minimum amount of water (amount depends on the salt).

  3. Mix the two solutions.

  4. Next you want to neutralize the solution, which is quite acidic. Stir in ammonia until the pH of the mixture is 7 or higher. Use a pH meter (or pH paper). Reacting ammonia, sodium bisulfate, and nitrates will give you sodium sulfate and ammonium nitrate.

  5. Sodium sulfate and ammonium nitrate have different solubilities in water, so boil the solution to get the sodium sulfate to crystallize. Remove the liquid from heat when crystals of sodium sulfate form in the bottom of the pan.

  6. Chill the solution in the freezer to get as much of the sodium sulfate as possible to drop out of the solution.

  7. Run the solution through a filter (coffee filter or paper towels) to separate the solid sodium sulfate from the ammonium nitrate solution.

  8. Allow the ammonium nitrate solution to evaporate, which will give you ammonium nitrate, with some sodium sulfate impurity. This is 'good enough' for most chemistry projects.

  9. If you want to further purify the ammonium nitrate, dissolve it in about 500 ml of methanol. The ammonium nitrate is soluble in methanol, while the sodium sulfate is not.

  10. Run the solution through a filter, which will give you sodium sulfate on the filter and a solution of ammonium nitrate.

  11. Allow the methanol to evaporate from the solution to obtain crystalline ammonium nitrate.

Safety Information

The chemicals used in this project are smelly and corrosive, so this project should be performed under a fume hood or outdoors. As always, wear gloves, eye protection, and appropriate clothing. Some of the reagents and the final product are flammable or are oxidizers, so keep the chemicals away from open flames. NurdRage has a wonderful YouTube video outlining the steps of this reaction and showing you what to expect along the way.

Comments

May 14, 2010 at 3:51 pm
(1) John says:

Hi, I’d like to know the amount of each chemical product to produce one pound of ammonium nitrate

September 7, 2012 at 11:47 am
(2) Anon says:

I don’t think anyone wants to do all the calculations for you. Might I suggest you take a chemistry course and do the calculations yourself. It will of course vary depending on which ingredients you use. If someone’s using household chemicals nobody can give you an exact answer without knowing the complete contents of the exact chemicals you will be using.

October 31, 2012 at 1:45 pm
(3) Gubsy says:

Can u use cloudy ammonia in this reaction

April 7, 2013 at 11:48 am
(4) your friendly neighbour says:

Where can i buy nitrate salt?

May 10, 2013 at 9:28 am
(5) david says:

@your friendly neigbour it is used as a salt alternative, eg “lite salt” this is sodium nitrate

July 25, 2013 at 7:03 am
(6) Chazoell says:

If you need to ask where to buy nitrate salts from you shouldn’t be attempting to make this

August 12, 2013 at 12:00 am
(7) anon45 says:

all you have to do is triple the amount shown to make a bigger solution. Triple decker just add. You don’t need a chemistry course.

March 7, 2014 at 9:07 am
(8) TrollFaceTheMan says:

I am a little bit confused about this article about Ammonium Nitrate…

Ammonium Nitrate (NH4NO3) is a Horrible Oxidizer and is NOT used at All in Pyrotechnics… It is way to Hygroscopic and renders itself completely useless in even short term exposures to air…

It is not similar to Potassium Nitrate (KNO3) or Sodium Nitrate (NaKO3) (Both Good Oxidizers) in any way quality wise… However with another process you can covert Ammonium Nitrate in Sodium nitrate for use in Pyrotechnics using Sodium Hydroxide, or Potassium Nitrate using Potassium Hydroxide…

Also it should be pointed out not all instant cold packs contain Ammonium Nitrate some have Urea in them Instead so always make sure you know what chemical your using…

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