Manganese dioxide (manganous anhydride) (MnO2) . It is the most important of the manganese oxides. It is prepared by the action of a slightly nitric solution of potassium permanganate on a manganous salt, such as sulfate. It is a brown or blackish product, insoluble in water, with a density close to 5, which is presented in mass or powder.
Summary
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- 1 Story
- 2 Description
- 3 Uses
- 4 Properties
- 1 Physical properties
- 5 Obtaining
- 6 Applications
- 7 Precautions
- 8 Production
- 9 References
- 10 Sources
History
The use of manganese dioxide dates back 17,000 years to the Upper Paleolithic period , when Stone Age men used it as a pigment for their cave paintings. The Spartans of Ancient Greece used MnO 2 in their steelmaking , thereby creating superior weapons to those of their enemies. The Egyptians and the Romans used manganese ore to give pink, purple, and black tints to the glass they made
. In the mid [[| 18th century | 18th century]], manganese oxide was a main ingredient in the manufacture of chlorine. In 1816, a German researcher realized that manganese increased the hardness of theiron , without compromising its flexibility or strength.
In 1868 , Georges Leclanché developed the dry cell battery I using manganese dioxide. The battery industry is the second largest consumer of manganese today. The uses for MnO 2, like many of the technologies used today in water treatment , have a long history.
Description
Manganese dioxide (MnO 2) is an inorganic compound. It is a black to brown material that occurs naturally as a pyrolusite mineral . In addition to being used for water treatment, MnO 2 has various uses, including manufacturing batteries, beverage cans, agricultural pesticides and fungicides, and electronic circuits.
Chemical reactions and physical processes of MnO 2 media is a topic that every water treatment specialist should understand and be competent to use in groundwater applications in their region.
the technologyManganese dioxide is one of the most commonly used and least understood applications for removing iron , manganese , hydrogen sulfide , arsenic and radium . MnO 2 is not a magic powder, but a catalyst used to improve water quality in applications ranging from private wells to large municipalities.
Applications
It is used as a source of manganese and all its compounds, it is also used as an oxidant in alkaline batteries, in paints and varnish | varnishes]], for painting crystals , ceramics, porcelain , electrotechnics, pigments, textiles, etc. And in obtaining chlorine , iodine and as a depolarizer in dry cells
Properties
The substance is a strong oxidant and reacts violently with combustible materials , reducers and aluminum in the presence of intense heat .
Physical properties
- Semi-developed formula:
MnO2
- Density:
5,026 g / cm3 (solid)
- Molecular mass UMA Unit of Atomic Mass:
86.9368 g / mol
- Melting point temperature of the moment in which a substance goes from the solid state to the liquid state:
535 ° C (decomposes)
- Appearance:
Solid black. === Chemical properties ===
- Water solubility:
Insoluble.
Obtaining
It is found in nature as a pyrolusite mineral or it can be artificially produced.
Applications
It is used in paints and varnishes, for painting crystals and ceramics, in obtaining chlorine and iodine and as a depolarizer in dry cell batteries
Cautions
Excess manganese is toxic. Prolonged exposures to manganese compounds , inhaled or oral, can cause adverse effects on the nervous , respiratory, and other systems. Potassium permanganate, KMnO4, is corrosive. Excess manganese is toxic. Prolonged exposures to manganese compounds, inhaled or oral, can cause adverse effects on the nervous , respiratory, and other systems. Potassium permanganate, KMnO4, is corrosive.
Production
The countries with the largest manganese ore deposits are South Africa , Ukraine and China . Metal is obtained by reducing oxides with aluminum , and ferromanganese is also obtained by reducing iron and manganese oxides with carbon . It can also be obtained by electrolysis of manganese sulfate: MnSO4 + H2O → Mn + H2SO4 + ½ O2
