The manganese chloride is an inorganic salt whose chemical formula is MnCltwo. It is made up of Mn ionstwo+ and Cl- in a 1: 2 ratio; for each Mn cationtwo+ there are twice as many Cl anions-.
This salt can form various hydrates: MnCltwo2HtwoO, (dihydrate), MnCltwo4HtwoO (tetrahydrate), and MnCltwo6HtwoO (hexahydrate) The most common form of salt is tetrahydrate.
The physical properties of manganese chloride such as density, melting point and solubility in water, are influenced by its degree of hydration. For example, the melting point of the anhydrous form is much higher than that of the tetrahydrate form..
The color of manganese chloride is pale pink (top image). Paleness is characteristic of transition metal salts. Manganese chloride is a weak Lewis acid.
The mineral known as escacquita is the naturally anhydrous form of manganese (II) chloride; like the kempita.
Manganese (II) chloride is used as an alloying agent; catalyst in chlorination reactions, etc..
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- Anhydrous form: pink cubic crystals.
- Tetrahydrate form: slightly deliquescent reddish monoclinic crystals.
- Anhydrous: 125.838 g / mol.
- Dihydrate: 161.874 g / mol.
- Tetrahydrate: 197.91 g / mol.
- Anhydrous: 654 ºC.
- Dihydrate: 135 ºC.
- Tetrahydrate: 58 ºC.
Anhydrous form: 1,190 ºC.
- Anhydrous: 2,977 g / cm3.
- Dihydrate: 2.27 g / cm3.
- Tetrahydrate: 2.01 g / cm3.
Anhydrous form: 63.4 g / 100 ml at 0 ° C; 73.9 g / 100 ml at 20 ° C; 88.5 g / 100 ml at 40 ° C; and 123.8 g / 100 ml at 100 ° C.
Soluble in pyridine and ethanol, insoluble in ether.
Unless proper precautions are taken, dehydration of the hydrated forms to the anhydrous form can lead to hydrolytic dehydration, with the production of hydrogen chloride and manganese oxychloride..
A 0.2 M solution of manganese chloride tetrahydrate in aqueous solution has a pH of 5.5.
It is stable, but sensitive to moisture and incompatible with strong acids, reactive metals, and hydrogen peroxide.
Starting with the tetrahydrated salt, with striking pink crystals, it must be made up of coordination complexes (top image). In them, the metallic center of Mntwo+ is surrounded by an octahedron defined by four molecules of HtwoO and two Cl anions-.
Note that the Cl ligands- are in cis positions; all are equivalent in the rectangular base of the octahedron, and it does not matter if the Cl is "moved"- to any of the other three positions. Another possible isomer for this coordinate molecule is in which both Cl- are in trans positions; that is, in different extremes (one above and the other below).
The four water molecules with their hydrogen bonds allow two or more octahedra to be joined by dipole-dipole forces. These bridges are highly directional, and adding the electrostatic interactions between the Mntwo+ and Cl-, establish an ordered structure characteristic of a crystal.
The pink color of MnCltwo4HtwoOr is it due to the electronic transitions of the Mntwo+ and its configuration d5. Likewise, the disturbances caused by the proximity of water molecules and chlorides modify the amount of energy required to be absorbed by such electrons d5 to travel higher energy levels.
The salt has been dehydrated and its formula is now MnCltwo2HtwoO. What about the octahedron above? Nothing, except that the two molecules of HtwoOr that dropped out are replaced by two Cl-.
At first you may give the wrong impression that there are four Cl- for each Mntwo+; however, the half of the octahedron (axially) is actually the repeating unit of the crystal.
Thus, it is true that there is a Mntwo+ coordinated to two Cl- and two water molecules in trans positions. But for this unit to interact with another it needs two Cl bridges, which in turn allows the coordination octahedron for manganese to be completed..
In addition to Cl bridges, water molecules also collaborate with their hydrogen bonds so that this MnCl chaintwo2HtwoOr do not disarm.
Finally, the magnesium chloride has finished losing all the water contained in its crystals; we now have the anhydrous salt, MnCltwo. Without the water molecules, the crystals noticeably lose the intensity of their pink coloration. The octahedron, as for hydrates, remains unchanged by the very nature of manganese.
Without water molecules, Mntwo+ ends surrounded by an octahedron composed only of Cl-. This coordination bond is both covalent and ionic in character; for this reason it usually refers to the structure of MnCltwo like a polymeric crystal. In it there are alternate layers of Mn and Cl.
Manganese has many possible oxidation states. Because of that, the traditional nomenclature for MnCltwo it is not clarified.
On the other hand, manganese chloride corresponds to its best known name, to which it would be necessary to add the '(II)' to make it agree with the stock nomenclature: manganese (II) chloride. And likewise, there is the systematic nomenclature: manganese dichloride.
Manganese chloride serves as a catalyst for the chlorination of organic compounds.
Manganese chloride is used as a raw material for the manufacture of antiknockers for gasoline; welding material for non-ferrous metals; intermediary in the manufacture of pigments; and linseed oil dryer.
It is used in the textile industry for printing and dyeing; in the production of various manganese salts, including methylcyclopentadienylmanganese tricarbonyl used as a brick colorant; and in the production of dry electric cells.
Manganese chloride is used as an alloying agent and is added to molten magnesium to produce manganese-magnesium alloys; as an intermediate in the preparation of drying agents for paint and varnish; and as a component of disinfectants.
It is also used in the purification of magnesium.
Manganese chloride is used as a source of manganese, an element that, although it is not a primary nutritional element for plants such as nitrogen, phosphorus and potassium, is used in numerous biochemical reactions typical of these living beings.
It is also added to the feed of breeding animals to supply manganese, an essential trace element for the growth of animals..
Manganese chloride is a dietary component that supplies manganese, an element that is involved in many processes necessary for life, including: synthesis of fatty acids and sex hormones; assimilation of vitamin E; cartilage production; etc.
It can cause redness, irritation and dermatitis on contact with the skin. Manganese Chloride causes red, sore and watery eyes.
When inhaled, salt causes a cough, sore throat, and shortness of breath. On the other hand, ingestion could cause vomiting, nausea and diarrhea..
Chronic excessive inhalation of this salt can lead to lung inflammation and subsequent reactive airway disease..
Its excessive ingestion can cause mental disorders, dehydration, hypotension, liver and kidney failure, failure of the multiorgan system and death..
Neurotoxicity is the initial manifestation of the undesirable action of manganese, and may present headaches, dizziness, memory loss, hyperreflexia, and mild tremor..
Severe toxicity is manifested by symptoms and signs similar to those seen in Parkinson's disease.
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