Permanganate

A permanganate is the general name for a chemical compound containing the manganate(VII) ion, (MnO₄⁻). Because manganese is in the +7 oxidation state, the permanganate(VII) ion is a strong oxidizing agent. The ion has tetrahedral geometry. Permanganate solutions are purple in color and are stable in neutral or slightly alkaline media.The exact chemical reaction is dependent upon the organic contaminants present and the oxidant utilized. For example, trichloroethene (C₂HCl₃) is oxidized by sodium permanganate to form carbon dioxide (CO₂), manganese dioxide (MnO₂), sodium ions (Na⁺), hydronium ions (H⁺), and chloride ions (Cl⁻).

In an acidic solution, permanganate(VII) is reduced to the colourless +2 oxidation state of the manganese(II) (Mn²⁺) ion.

In a strongly basic solution, permanganate(VII) is reduced to the green +6 oxidation state of the manganate ion, MnO₄²⁻.

In a neutral medium however, it gets reduced to the brown +4 oxidation state of manganese dioxide MnO₂.

Production

Permanganates can be produced by oxidation of manganese compounds such as manganese chloride or manganese sulfate by strong oxidizing agents, for instance, sodium hypochlorite or lead dioxide:

Manganese dioxide

Manganese(IV) oxide is the inorganic compound with the formula MnO
2. This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for MnO₂ is for dry-cell batteries, such as the alkaline battery and the zinc-carbon battery.MnO
2 is also used as a pigment and as a precursor to other manganese compounds, such as KMnO
4. It is used as a reagent in organic synthesis, for example, for the oxidation of allylic alcohols. MnO₂ in the α polymorph can incorporate a variety of atoms (as well as water molecules) in the "tunnels" or "channels" between the magnesium oxide octahedra. There is considerable interest in α-MnO₂ as a possible cathode for lithium ion batteries.

Structure

Several polymorphs of MnO
2 are claimed, as well as a hydrated form. Like many other dioxides, MnO
2 crystallizes in the rutile crystal structure (this polymorph is called β-MnO
2), with three-coordinate oxide and octahedral metal centres.MnO
2 is characteristically nonstoichiometric, being deficient in oxygen. The complicated solid-state chemistry of this material is relevant to the lore of "freshly prepared" MnO
2 in organic synthesis. The α-polymorph of MnO
2 has a very open structure with ``channels" which can accommodate metal atoms such as silver or barium. α-MnO₂ is often called Hollandite, after a closely related mineral.

Manganese(II) oxide

Manganese(II) oxide (systematically named manganese(2+) oxide(2−)) is an inorganic compound with chemical formula MnO. It forms green crystals. The compound is produced on a large scale as a component of fertilizers and food additives.

Structure, stoichiometry, reactivity

Like many monoxides, MnO adopts the rock salt structure, where cations and anions are both octahedrally coordinated. Also like many oxides, manganese(II) oxide is often nonstoichiometric: its composition can vary from MnO to MnO_1.045.

Below 118 K MnO is antiferromagnetic. MnO has the distinction of being one of the first compounds to have its magnetic structure determined by neutron diffraction, the report appearing in 1951. This study showed that the Mn²⁺ ions form a face centered cubic magnetic sub-lattice where there are ferromagnetically coupled sheets that are anti-parallel with adjacent sheets.

Manganese(II) oxide undergoes the chemical reactions typical of an ionic oxide. Upon treatment with acids, it converts to the corresponding manganese(II) salt and water. Oxidation of manganese(II) oxide gives manganese(III) oxide.

Schöneberg

Schöneberg is a locality of Berlin, Germany. Until Berlin's 2001 administrative reform it was a separate borough including the locality of Friedenau. Together with the former borough of Tempelhof it is now part of the new borough of Tempelhof-Schöneberg.

History

The village was first documented in a 1264 deed issued by Margrave Otto III of Brandenburg. In 1751 Bohemian weavers founded Neu-Schöneberg also known as Böhmisch-Schöneberg along northern Hauptstraße. During the Seven Years' War on 7 October 1760 Schöneberg and its village church were completely destroyed by a fire due to the joint attack on Berlin by Habsburg and Russian troops.

Both Alt-Schöneberg and Neu-Schöneberg were in an area developed in the course of industrialization and incorporated in a street network laid out in the Hobrecht-Plan in an area that came to be known architecturally as the Wilhelmine Ring. The two villages were not combined as one entity until 1874 and received town privileges in 1898. In the following year it was disentangled from the Kreis Teltow and became a Prussian Stadtkreis (independent city). Many of the former peasants gained wealth by selling their acres to the settlement companies of growing Berlin and built luxurious mansions on Hauptstraße. The large town hall Rathaus Schöneberg was completed in 1914. In 1920 Schöneberg became a part of Greater Berlin. Subsequent to World War II the Rathaus served as the city hall of West Berlin until 1991 when the administration of the reunited City of Berlin moved back to the Rotes Rathaus in Mitte.

Schöneberg (Hofgeismar)

Schöneberg is a village and a municipal district of the town of Hofgeismar in the district of Kassel in northern Hesse, Germany. West of the village, there are the ruins of a castle dating from the 12th century that bears the same name.

Geography

Schöneberg is a straßendorf, a village that straddles a main road. Schöneberg lies on the western edge of the Reinhardswald and is home to 600 residents. The German Bundesstraße 83 between Kassel and Bremen runs through town.

History

Castle

To exert their power and influence, and for protection, in the early part of the 12th century, the archbishops of Mainz in the Diemel and upper Weser area built a fortress on top of a mountain 323 meters (1,060 ft) high, just west of where the village stands today. Today, the castle stands in ruins.

Lords of Schöneberg

The lords of Schöneberg appeared in the High Middle Ages in northern Hesse and bore the title nobilis Dominus. Their domain stretched through scattered seats from Schöneberg to the Reinhardswald. The castle was built by Count Hermann II of Winzenburg.

Schöneberg, Brandenburg

Schöneberg is a municipality in the Uckermark district, in Brandenburg, Germany.

References

Media related to Schöneberg (Uckermark) at Wikimedia Commons