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Zinc nitrate: structure, properties, obtaining, uses

Its chemical formula is Zn (NO 3 ) 2 . It is a colorless crystalline solid that tends to absorb water from the environment. It can be obtained by treating zinc metal with dilute nitric acid. It is a strongly oxidizing compound.

Zinc nitrate Zn (NO 3 ) 2 . Ondřej Mangl / Public domain. Source: Wikimedia Commons.

It serves as an accelerator of organic chemistry reactions and allows to obtain composite polymers with electrically conductive properties. It is used to form layers of materials useful in electronics.

It is part of some liquid fertilizers and certain slow-release herbicides. It helps in the preparation of complex oxides, improving their density and electrical conductivity.

Although it is not combustible, it can accelerate the burning of substances that are, such as charcoal or organic materials. It is irritating to the skin, eyes and mucous membranes, and it is very toxic to aquatic life.

Structure

Zinc nitrate is an ionic compound. It has a bivalent cation (Zn 2+ ) and two monovalent anions (NO  ). The nitrate anion is a polyatomic ion formed by a nitrogen atom in its oxidation state +5 covalently bonded to three oxygen atoms with a valence of -2.

Ionic structure of zinc nitrate. Edgar181 / Public domain. Source: Wikimedia Commons.

The image below shows the spatial structure of this compound. The central gray sphere is zinc, the blue spheres are nitrogen, and the red spheres represent oxygen.

Spatial structure of Zn (NO 3 ) 2 . Zinc is in the middle of nitrate ions. Grasso Luigi / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0). Source: Wikimedia Commons.

Nomenclature

  • Zinc nitrate
  • Zinc dinitrate

Properties

Physical state

Colorless or white crystalline solid.

Molecular weight

189.40 g / mol

Melting point

Approximately 110 ºC.

Boiling point

Approximately 125 ºC.

Density

2,065 g / cm 3

Solubility

Soluble in water: 120 g / 100 g H 2 O at 25 ° C. Soluble in alcohol.

pH

Its aqueous solutions are acidic. A 5% solution has a pH of approximately 5.

Chemical properties

Because it is a nitrate, this compound is a strong oxidant. Reacts violently with carbon, copper, metal sulfides, organic matter , phosphorus, and sulfur. If sprayed on hot coal it explodes.

2 Zn (NO 3 ) 2  + heat → 2 ZnO + 4 NO 2 ↑ + O 2 ↑

In alkaline solutions, such as those of NaOH, the zinc in this compound forms its hydroxide and other complex species:

Zn (NO 3 ) 2 + 2 OH  → Zn (OH) 2 + 2 NO 

Zn (OH) 2 + 2 OH  → [Zn (OH) 4 ] 2-

Obtaining

It can be obtained by treating zinc or zinc oxide with dilute nitric acid. Hydrogen gas is formed in this reaction.

Zn + 2 HNO 3 → Zn (NO 3 ) 2 + H 2 ↑

Applications

In reaction catalysis

It is used as a catalyst in obtaining other chemical compounds such as resins and polymers. It is an acid catalyst.

Example of resin. Bugman at English Wikipedia / Public domain. Source: Wikimedia Commons.
Structure model of a polymer. Ilmari Karonen / Public domain. Source: Wikimedia Commons.

Another case of acceleration of reactions is the catalytic system of Zn (NO 3 ) 2 / VOC 2 O 4, which allows the oxidation of α-hydroxyesters to α-ketoesters with a 99% conversion even at ambient pressure and temperature.

In composite polymers

Polymethylmethacrylate and Zn (NO 3 ) 2 films have been developed with electrical conductivity properties that make them suitable candidates for use in supercapacitors and high-speed computers.

In oxisales cements

With aqueous solutions of zinc nitrate and zinc oxide powder, materials that belong to the class of cements generated by an acid-base reaction are obtained.

These present a reasonable resistance to dissolving in dilute acids and alkalis, developing a resistance to compression comparable to that of other cements such as those of zinc oxychlorides.

This property increases when the ZnO / Zn (NO 3 ) 2 ratio increases , and when the concentration of Zn (NO 3 ) 2 in the solution increases. The cements obtained are completely amorphous, that is, they do not have crystals.

With zinc nitrate, tests have been carried out to obtain cements. Author: Kobthanapong. Source: Pixabay.

In zinc oxide coatings and nanomaterials

Zn (NO 3 ) 2 is used for the electrolytic deposition of very thin layers of zinc oxide (ZnO) on various substrates. Nanostructures of this oxide are also prepared on the surfaces.

Zinc oxide nanoparticles. Some ZnO nanostructures can be prepared with Zn (NO 3 ) 2 . Verena Wilhelmi, Ute Fischer, Heike Weighardt, Klaus Schulze-Osthoff, Carmen Nickel, Burkhard Stahlmecke, Thomas AJ Kuhlbusch, Agnes M. Scherbart, Charlotte Esser, Roel PF Schins, Catrin Albrecht / CC BY (https://creativecommons.org/ licenses / by / 2.5). Source: Wikimedia Commons.

ZnO is a material of great interest due to the multitude of applications in the field of optoelectronics, it also has semiconductor properties and is used in sensors and transducers.

In herbicides

Zinc nitrate has been used in conjunction with some organic compounds to slow the release rate of certain herbicides into water. The slow release of these products allows them to be available for a longer time and fewer applications are required.

In anode manufacturing

It stimulates the sintering process and improves the density of certain oxides that are used to make anodes for fuel cells. Sintering is obtaining a solid material by heating and compressing a powder without reaching its fusion.

Drawing of how the sintering of two grains occurs. Zn (NO 3 ) 2 helps in the execution of this process on some complex oxides. Cdang / Public domain. Source: Wikimedia Commons.

The materials tested are complex oxides of strontium, iridium, iron and titanium. The presence of zinc significantly increases the electrical conductivity of these.

Other apps

It is used in obtaining drugs. It acts as a mordant in the application of inks and colorants. Serves as a latex coagulant. It is a source of zinc and nitrogen in liquid fertilizers.

Potential use in bone tissue engineering

This compound has been used as an additive in the elaboration of reinforcements or frameworks for the regeneration of bone fibers, since it allows to improve the mechanical resistance of these structures.

The zinc-containing scaffold has been found to be non-toxic to osteoprogenitor cells, supports the activity of osteoblasts, the bone-making cells, and improves their adhesion and proliferation.

It favors the formation of apatite, which is the mineral that forms bones and also has an antibacterial effect.

Zn (NO 3 ) 2 could be very useful for the reconstruction of bone matter in people who have suffered accidents. Mariano Coretti / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0). Source: Wikimedia Commons.

Risks

It is a material with a potential risk of fire and explosion.

It is not combustible but accelerates the burning of combustible materials. If a large amount of this compound is involved in a fire or if the combustible material is finely divided, an explosion can occur.

When subjected to strong heat, toxic gases of nitrogen oxides are produced. And if the exposure is carried out for a long time, it can explode.

It is irritating to the skin, can cause serious eye damage, respiratory tract irritation, is toxic if swallowed and causes damage to the digestive tract.

Very toxic to aquatic life with long lasting effects.

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