Ammonium Perchlorate
Ammonium Perchlorate has no known hydrates. It is a good oxidiser for propellant as all it's combustion products are gaseous and it produces little smoke. It has a melting point (with decomposition) of 450C.
Ammonium Perchlorate cannot be made by electrolysis of Ammonium Chloride (or Chlorate). Ammonium Chlorate is an unstable, dangerous compound.
The procedures for making Ammonium Perchlorate assumes that you have pure Sodium Perchlorate to start with. There must be NO Chlorate present as Ammonium Chlorate will form. Ammonium Chlorate is an unstable compound that is liable to explode at 106C. It is very dangerous when mixed with combustible materials and will be liable to ignite spontaneously at much lower temperatures. All Chlorate must be destroyed by chemical means before starting to make Ammonium Perchlorate. Recrystallizing the Sodium Perchlorate will not be good enough as there will be some Sodium Chlorate contaminant in the recrystallized product. The Sodium Chlorate should be destroyed by using an excess of chemicals or, if you are more exacting, you can use what you think is needed to destroy the chlorate and then test for the presence of Chlorate by using a sensitive test for Chlorate, like Indigo Carmine (see elsewhere on this page).
| Solubility of Ammonium Perchlorate in water |
|---|
| Temp. OC | g/100g soln. | g/100mL satd. soln. | g/100mL H2O |
| -2.7, eutectic | 9.8 | -- | -- |
| 0 | 10.74 | 11.56 | 12 |
| 20 | -- | 20.85 | -- |
| 25 | 20.02 | -- | 25 |
| 40 | -- | 30.58 | -- |
| 45 | 28.02 | -- | 39 |
| 60 | 33.64 | 39.05 | -- |
| 75 | 39.45 | -- | 65 |
| 80 | -- | 48.19 | -- |
| 100 | -- | 57.01 | 88 |
Making NH4ClO4
Ammonium Perchlorate from Sodium Perchlorate and Ammonium Chloride
Ammonium Perchlorate from Sodium Perchlorate and Ammonium Nitrate
Ammonium Perchlorate from Sodium Perchlorate and Ammonium Sulphate
Ammonium Perchlorate from Sodium Perchlorate and Ammonium Hydroxide or Ammonia gas
Ammonium Perchlorate from Potassium or Barium Perchlorate
Ammonium Perchlorate can be made by adding Ammonia gas, Ammonium Hydroxide or Carbonate to Perchloric acid.
Ammonium Perchlroate can also be make via Lithium Perchlorate and Ammonium Carbonate. The Lithium Carbonate so produced is insoluble and will precipitate leaving the Ammonium Perchlorate in solution. See the Li Perchlorate section for US Pat. No. 3,020,124.
Uses of Ammonium Perchlorate
Ammonium Perchlorate is used as the oxidiser in rocked propellants. It has a high oxygen content,
it's decomposition products are all low molecular weight gasses, it's 'n' value is suitable and it produces little visible smoke. It is also used in pyrotechnics for the blue colour it produces amongst other things.
When used as a rocket propellant it must have a certain range of crystal sizes in order to give the required burning characteristics. The manufacturers of Ammonium Perchlorate obtain theses crystal sizes by careful control and regulation of the crystallization stages in the manufacturing process. For the amateur batch producer it is harder to obtain a product that has the required range of crystal size. The Author is not aware of any cooling schedules, after re dissolving the Ammonium Perchlorate, that will give a ppt of the Perchlorate with a predetermined crystal size distribution. US Patent No.2,739,873 discusses cooling schedules for a continuous industrial set up, in order to give desired crystal size/blend/range. See Chemical Engineering Progress in 'Further Reading Section".
Mesh sizes greater than 200 are preferably whole crystals with rounded corners. Theses crystals are formed by cooling/growing schedules. Smaller sized are usually produced in impact mills (ball mills). The sized and distribution of sizes of oxidiser will have a large effect on burn rated of propellants. The particle size will also have a large effect on the "pourability" of the propellant when it is ready to be loaded into a motor. The larger the particle size the more "pourable" the mixture.
When Ammonium Perchlorate is used, together with other chemicals, for colour production in pyrotechnic devices it is not advisable to use Sodium Perchlorate for to make it. It is very difficult to eliminate all Sodium ion contamination which will result in orange (Sodium) colour contamination.
![[Cyrstal of Ammonium Perchlorate showing occluded fluid]](_img/occluded.gif)
Ammonium Perchlorate crystals have a tendency to trap water within the crystals (occluded moisture) and this can be difficult to remove by drying. It can slowly make it's way to the surface of the crystal where it will cause caking of the Perchlorate. Ammonium Perchlorate is often packed with silica gel to help counteract this problem. This moisture can be a problem when the Perchlorate is used with water sensitive compounds. If the moisture is exposed by milling it can be removed by further drying.
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