The calcium nitrate is a tertiary inorganic salt whose chemical formula is Ca (NO3)two. From its formula it is known that its solid is composed of Ca ionstwo+ and no3- in a 1: 2 ratio. Therefore, it is a compound of purely ionic nature..
One of its properties is its oxidizing character, due to the nitrate anion. It is not combustible, that is, it does not burn at high temperatures. Being non-combustible, it represents a safe solid to handle without much care; however, it can accelerate the ignition of combustible materials.
Its appearance consists of a granular solid, which has a white or light gray color (upper image). It can be anhydrous or tetrahydrate, Ca (NO3)two4HtwoO. It is very soluble in water, methanol and acetone.
Calcium nitrate has been widely used as a fertilizer, as it travels easily in moist soil, and is quickly absorbed by plant roots. Provides two important elements for plant nutrition and growth: nitrogen and calcium.
Nitrogen is one of the three essential elements for the development of plants (N, P and K), it is essential in the synthesis of proteins. Meanwhile, calcium is necessary to maintain the structure of the plant cell wall. For this reason Ca (NO3)two a lot goes to gardens.
On the other hand, this salt has toxic actions, especially by direct contact with the skin and eyes, as well as by inhaling its dust. In addition, it can be decomposed by heating.
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The upper image shows the structure of Ca (NO3)two in a model of spheres and bars. Here, however, there is a flaw: the existence of Ca-O covalent bonds is assumed, which contradicts their ionic character. Clarifying this, really the interactions are of the electrostatic type.
The cation Catwo+ surrounds itself with two NO anions3- according to its proportions on the glass. Therefore, nitrogen predominates in the form of nitrate in the crystalline structure..
The ions are grouped in such a way that they establish a configuration whose minimum expression is the unit cell; which, for the anhydrous salt, is cubic. That is, from cubes containing the 1: 2 ratio for these ions, the entire crystal is reproduced.
On the other hand, the tetrahydrate salt, Ca (NO3)two4HtwoOr, it has four water molecules for each set NO3- ACtwo+ NOT3-. This modifies the crystal structure, deforming it into a monoclinic unit cell..
Therefore, the crystals for both the anhydrous and the tetrahydrate salts are expected to be different; differences that can be determined in their physical properties, for example melting points.
-Calcium nitrate
-Calcium dinitrate
-Nitrocalcite
-Norwegian saltpeter and limesaltpetro.
Spout3)two or CaNtwoOR6
Anhydrous 164.088 g / mol and tetrahydrate 236.15 g / mol. Note the effect of water on the molecular weight, and it cannot be neglected when weighing it..
White or light gray solid or granules. Cubic white crystals or deliquescent granules; that is, they absorb moisture to the point that they dissolve as a result of their high solubility.
The anhydrous form decomposes on heating to a temperature that prevents the determination of its boiling point; while the tetrahydrate form of the salt has a boiling point of 132ºC (270ºF, 405K).
-Anhydrous form: 561 ° C to 760 mmHg (1042 ° F, 834 K).
-Tetrahydrate form: 42.7 ° C (109 ° F, 316 K).
This shows how water molecules interfere with electrostatic interactions between Catwo+ and no3- inside the crystals; and consequently, the solid melts at a much lower temperature.
-Anhydrous form: 1212 g / L at 20 ºC.
-Tetrahydrate form: 1290 g / L at 20 ºC.
The water in the crystals hardly increases the solubility of the salt.
-In ethanol, 51.42 g / 100 g at 20 ° C.
-In methanol, 134 g / 100 g at 10 ° C.
-In acetone, 168 g / 100 g at 20 ° C.
6.0
2.5 g / cm3 at 25 ºC (tetrahydrate).
When calcium nitrate is heated to incandescence, it decomposes into calcium oxide, nitrogen oxide and oxygen..
It is a strongly oxidizing agent, but it is not combustible. Accelerates the ignition of combustible materials. The division of calcium nitrate into fine particles, facilitates its explosion when the compound is exposed to prolonged fire.
Mixtures with alkyl esters become explosive by originating alkyl nitrate esters. The combination of calcium nitrate with phosphorus, tin (II) chloride or other reducing agent, can react explosively.
It is used in crops as a source of nitrogen and calcium. Calcium nitrate is very soluble in water and easily absorbed by plant roots. In addition, it does not acidify soils because its ions cannot be significantly hydrolyzed..
Mixing with fertilizers containing phosphorus or sulfate should be avoided to avoid the formation of insoluble salts. Due to its hygroscopicity, it should be stored in a dry and cool environment.
Its use has an advantage over the use of ammonium nitrate as a fertilizer. Although this last compound contributes nitrogen to plants, it interferes with the absorption of calcium, which could lead to a calcium deficiency in plants..
Calcium contributes to the maintenance of the cell wall structure of plants. In the presence of a calcium deficiency, the growing tissues of plants, such as root tips, young leaves, and shoot tips, often show distorted growth..
Calcium nitrate reduces the accumulation of volatile fatty acids and phenolic compounds, phytotoxic that accumulate due to the decomposition of soybean crop residues.
In addition, there is a tendency for calcium nitrate to decrease the ammonium concentration in the soil, which increases the hydrogen buffering capacity..
Calcium nitrate is used to reduce the setting time of concrete. This is produced by the generation of calcium hydroxide, perhaps through a double displacement reaction..
In addition, calcium nitrate induces the generation of the iron hydroxide compound, whose protective action on concrete reduces its corrosion. That is, the iron present can react with the basic components of concrete, such as calcium hydroxide itself..
Calcium nitrate decreases the setting time, as well as the resistance of the concrete, to which volcanic ash has been added. To study the effect of adding calcium nitrate to concrete, increasing concentrations of calcium nitrate have been used, between 2% and 10%..
A greater decrease in setting time has been observed, as well as an increase in concrete strength as the calcium nitrate concentration increased up to 10%.
Calcium nitrate is used to reduce odors from sewage by reducing the generation of hydrogen sulfide. In addition, the organic matter that generates anaerobic conditions is consumed, which makes it difficult for many biological species to survive..
Calcium nitrate tetrahydrate is an endothermic compound, that is, it has the ability to absorb heat from the surrounding environment. This produces a cooling of the bodies that come into contact with the containers that contain it..
The compresses increase their temperature, and to regenerate them it is enough to place them in a freezer
Calcium nitrate is used in the latex coagulation phase. It is part of the immersion solution, and when it comes into contact with the solution containing the latex, it breaks its stabilization and causes it to coagulate..
The binary mixture of molten nitrate salts, including calcium with other nitrates, is used in place of thermal oil in solar power plants for heat transfer and storage.
-Calcium nitrate is applied mixed with the soil at a concentration of 1.59 kg per 30.48 mtwo, with adequate watering. Calcium nitrate is solubilized in water, allowing its absorption by the roots of the plant. In hydroponic crops it dissolves in growing water.
-Calcium nitrate is also used in the form of a spray to spray the leaves and flowers, being an effective treatment in the prevention of the rotting of the tomato flower, the cork stain and the bitter pit of the apple..
-A quantity of calcium nitrate is added to the concrete-forming mixture (cement, sand, stones and water), and the effect that its addition has on the specific properties of the concrete is determined; such as setting speed and strength.
-Calcium nitrate is added at a suitable concentration to reduce odors from sewage or wastewater, to a level that odors are tolerable for people.
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