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Manganese(IV) oxide

Manganese(IV) oxide

Manganese dioxide is a compound of manganese(IV) with the formula MnO2.  It is a common precursor to many manganese compounds.

PropertiesEdit

ChemicalEdit

Manganese dioxide is a moderately strong oxidizing agent, and is used as such in the lab. It may be hydrated, but dehydration is easily accomplished by heating. The oxide is nonstoichiometric, with most samples being deficient in oxygen.

PhysicalEdit

Manganese dioxide is a brown to black solid which is insoluble in water.

AvailabilityEdit

Manganese dioxide is available at pottery supply stores for only a few dollars per pound. Lab grade manganese dioxide is also available from suppliers like Elemental Scientific.

It is often pulled from D cell zinc alkaline batteries. It is easy to obtain in this way, but it is very low grade. Soluble impurities can be washed from it, but it will contain large amounts of graphite which is not easily removed. This source of MnO2 is still useful for many applications.

PreparationEdit

This compound is often prepared in the lab inadvertently, as a byproduct to the an oxidation by potassium permanganate, such as that of toluene:

C6H5CH3 + 2KMnO4 → 2MnO2 + KC6H5COO + KOH + H2O

It can also be prepared by adding hydrogen peroxide to potassium permanganate.

Purification from crude, battery-grade sludge was done by NurdRage by utilizing equilibria. Alternatively, it can be done by precipitating iron and manganese oxalate, then adding an excess of oxalic acid to redissolve the iron (trisoxalatoferro complex, a pale green reminiscent of Fe(II)). The insoluble manganese oxalate can then be calcined at high temperature to decent purity.

Purification of Manganese Sulfate (NurdRage)

ProjectsEdit

HandlingEdit

SafetyEdit

Manganese dioxide is a heavy metal oxide, and is reasonably toxic. Ingestion or inhalation of large amounts of manganese will cause a disease called manganism. Manganese dioxide dust is irritant to eyes and mucous tissue.

Manganese dioxide will release chlorine gas in contact with hydrochloric acid.

Manganese dioxide is an oxidizer and can react with several organic compounds.

Manganese dioxide tends to stain nearly everything it touches, especially when wet or finely divided.

StorageEdit

Manganese dioxide is best stored in glass or plastic bottles and containers. Avoid storing the oxide in metal containers, especially steel, as it will rust the metal. Impure MnO2 can induce corrosion in certain types of stainless steels.

DisposalEdit

Manganese dioxide can be toxic to wildlife, so it's best to take it to disposal facilities. Since it's found in batteries, it can be taken to battery recycling centers.

ReferencesEdit

Relevant Sciencemadness threadsEdit

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