The term "nitrate" in chemistry means a salt of the well-known nitric acid, which contains a negatively charged part of NO3. In mineralogy and agriculture, another designation of nitrates is often used - saltpeter, but this name is also gradually replaced by a more scientifically sound one here.
Considering the basic chemical properties of nitrates, it is worth noting, first of all, that they are formed during the interaction of nitric acid with oxides, salts and, most often, with metals. At room temperature, almost all nitrates are highly stable, but when the temperature rises to 200-6000 ° C, they begin to melt, gradually decomposing into constituent elements.
By the way, by what elements nitrates are decomposed, one can judge what place they have in the electrochemical series of metal stresses. In particular, all nitrates, which upon decomposition give nitrites and oxygen molecules, contain metals located to the left of magnesium (for example, lithium, barium, aluminum, cobalt). The same nitrates, which, when decomposed, form nitrogen and metal oxides , as well as oxygen, are located in the electrochemical series in the interval from magnesium to copper.
Copper nitrate behaves in a special way: when it is decomposed, oxygen is not released, but divalent copper oxide and nitrogen dioxide are formed. And, for example, a silver nitrate solution , decomposing at a temperature of “only” 1700 ° C, releases not only pure oxygen with tetravalent nitric oxide, but also directly silver molecules.
It is also worth noting that absolutely all nitrates are the strongest oxidizing agents, and it is in the solid state. But in the solution they lose their oxidizing properties, differing, thereby, from the same nitric acid.
Since ancient times, people have noticed that nitric acid salts and, in the first place, nitrates are excellent fertilizers that have the ability to restore soil fertility. Later, a significant part of nitrates was used to create explosives and drugs.
A special role among all nitrates belongs to copper nitrate.
Copper nitrate (Cu (NO3) 2) is a complex inorganic substance related in its structure and chemical properties to salts of copper and nitric acid. By its physical properties, copper nitrate is a solid with a crystal lattice, which is perfectly soluble in water and a number of other solutions (for example, ethanol, ammonia liquid, ethyl acetate). At the same time, like a number of other salts of nitric acid, copper nitrate absorbs moisture well, forming specific crystals of dark blue color, which dissolve in air with high relative humidity.
The chemical properties of this nitrate are associated, on the one hand, with the fact that the molar mass of copper is constant and equal to 64 g / mol, and on the other, with the ability of copper nitrate to absorb moisture, thereby changing its name (nitrate - trihydrate - hexahydrate), and its properties. So, for example, anhydrous copper hydrate decomposes at a temperature of 1700 ° C, and trihydrate - already at 1200 ° C.
The molar mass of copper is also important in that the main way to obtain anhydrous copper nitrate is the synthesis of copper molecules and tetravalent copper oxide. It should be borne in mind that copper nitrate is a fairly toxic substance, therefore, its production and its storage must be carried out in accordance with all the basic requirements of safety regulations. In particular, it is necessary to be careful that this substance does not get on the mucous membranes or on the skin of a person, since in this case there is irritation that can cause various diseases.
By the way, almost all nitrates cause certain lesions of the skin. For example, the same solution of silver nitrate in contact with human skin causes the appearance of black spots, and if you hold it long enough, it can result in a burn.