Nitric Acid and Ammonia Concentrations as Factors Controlling the Thermal Decomposition of Ammonium Nitrate
The effect of nitric acid concentration in the condensed phase on the mutual relationship between endothermal and exothermal reactions in the decomposition process of molten ammonium nitrate in the 442–548 K range under standard pressure was investigated by means of DTA and TG. The decomposition of ammonium nitrate was found to consist of consecutive reactions. The first stage of decomposition is the endothermal reversible dissociation reaction of ammonium nitrate into amonia and nitric acid. The overall thermal effect of further consecutive reactions depending on sufficient nitric acid concentration is exothermal. An increase in ammonia concentration in liquid ammonium nitrate results in a decrease in nitric acid concentration. When the ammonia concentration will reach the value limiting the dissociation reaction rate of ammonium nitrate, it will also limit the overall decomposition rate and will limit the contribution of exothermal reactions.
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