The chemical substance ammonium nitrate, the formula of which is NH4NO3, has long been known to chemists, as early as 1659, it was discovered by I.R. Glauber. In the literature, another name for this compound is common - ammonium nitrate. Externally, ammonium nitrate is a white crystals with high hygroscopicity. The boiling point of the compound is 235 ° C, and at 169.6 ° C ammonium nitrate begins to melt. There are several crystalline modifications that quite significantly affect the chemical, physical properties and the scope of its application.
For example, these differences lie in the fact that different modifications of crystals have a different type of lattice. In total, there are five such modifications. The 1st modification is characterized by the cubic shape of the crystal lattice, the 2nd and 5th are tetragonic, and the 3rd and 4th are rhombic. In this case, as a result of transitions of the compound from one modification to another, a gradual, but steady increase in the volume of the unit cell is detected. This property causes a difference in chemical properties. So, for example, modification IV is characterized by a substance density of 1.725 g / cm3, the melting point is already 139.4 ° C.
The solubility of ammonium nitrate is as follows: in one hundred grams of water at a temperature of 0 ° C, 119 grams of substance are dissolved, at a temperature of 25 ° C, 212 grams are dissolved, and at 50 ° C - 346 grams of ammonium nitrate. In addition, ammonium nitrate can be dissolved in pyridine, methanol and ethanol. A very important characteristic of the compound is the fact that when an impact occurs or when the ambient temperature exceeds 270 ° C, ammonium nitrate decomposes, causing an explosive effect.
Using indicators, it is possible to determine the acidic environment that ammonium nitrate contains, hydrolysis with its participation is a reaction, the equation of which can be written as: NH4NO3 + H2O = NH4OH + HNO3. Ammonium nitrate reacts with alkaline solutions. As a result of such reactions, ammonia is formed, and the reaction process itself acts as a qualitative reaction to ammonium nitrate.
Typically, a substance is obtained by carrying out a neutralization reaction of 60% HNO3. NH3 in a gaseous state is used as a neutralizing substance. In the process, heat is generated, which is directed to the evaporation of a solution of ammonium nitrate and obtaining the substance in the form of granules.
The most common use of ammonium nitrate was in agriculture, as a valuable nitrogen fertilizer. The compound is also actively used in the manufacture of explosives, and as a reagent - as a solvent for zirconium in fuel rods, during nuclear waste recovery operations. Physico-chemical properties cause a constant increase in demand in the substance, so its production is growing steadily and today reaches 20 million tons per year, when recalculating the substance to the fraction of nitrogen.
Ammonium nitrate can be obtained in the laboratory under the strictest precautions and safety rules. To do this, in a ice bath, highly diluted nitric acid and ammonia are mixed (aqueous ammonia). It is best to carry out such a reaction remotely, for example, using manipulators, and being at a fairly safe distance from the location of the mixed solution. Carrying out the reaction consists in constantly mixing the acid in the ammonia solution during periodic verification by the indicator (litmus test) of the achievement of a neutral reaction state. In the same way, control over the course of the reaction is provided. If the acid medium is exceeded, an alkaline component is added to the solution, and vice versa.