Ammonium halates

The stabilities of the ammonium halates increase in the sequence NH4Br03 NH4CIO3 NH4IO3 [940]. Decompositions of the chlorate 

The sigmoid a—time curve for NH4C103 decomposition obeys [941] the Avrami—Erofe ev equation [eqn. (6), n = 2] with E 96 kJ mole-1 ( 320—345 K). Explosion occurred at 363 K for freshly prepared material but at a lower temperature for slightly older salt. 

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They also make the statement (no data or refs) that ammonium halates (-C103, -Br03 -IO3) are impact friction sensitive. This is in line with the thermochemical calculations and conclusions therefrom made by Shidlovskii (Ref 4) for both NH4I03 NH4I04... 

The sequence of thermal stabilities of the ammonium halates [48] is NH4Br03 < NH4C 03 < NH4IO3, and again it is proposed that the first step in reaction is proton transfer. Reactions proceed at interfaces by nucleation and growth mechanisms. 

From these measurements it appears that the stability of the compounds does not follow the expected order of chlorate < bromate < iodate. This behavior, however, cannot be regarded to be a characteristic property of ammonium halogenates only, because according to our experiments the same order of stability has been found in case of potassium halates. It is fairly difficult to propose a reliable reaction mechanism merely from kinetic data... 

Explosion of ammonium iodate took place at a temperature of 185°C, ie, very much higher than for the other halates (81°C for NH BrOa 90° for NH4CIO3). The explosion was preceded by a readily measurable and gradually accelerating decomposition. Contrary to the two other halates, self-heating was not observed before the explosion. The explosion was accompanied by a violet colored flash and produced a temperature increase of ouly l0°C in the reaction zone. The activation energy of the process leading to explosion was 38.4 kcal... 

A special study of interest is the one by Vitoria on mixtures of the chlorates of sodium and potassium. According to these experimental series, the eutectic point lies at 232°C for the mixture with 75% sodium chlorate. Otherwise, information on eutectics of halates or perhaiates is sparse, Hogan and Gordon have reported on oitectics of lithium nitrate or sodium nitrate and potassium perchlorate of M.P. 230 and 245 C respectively, and on those with alkaline earth nitrates. Ammonium and lithium perchlorate... 

Volume 30 H. Miyamoto and M. Salomon, Alkali Meta Halates, Ammonium lodate and Iodic Acid... 

Miyamoto H, Salomon M (1987) Alkali metal halates, ammonium iodate and iodic acid. lUPAC, Blackwell, London... 

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