Manganese dioxide is an inorganic compound with the chemical formula MnO2, which exists in the form of pyrolusite. Physical properties: black amorphous powder or black orthorhombic crystals. Solubility: hardly soluble in water, weak acid, weak base, nitric acid, cold sulfuric acid, pulverize concentrated hydrochloric acid under heating to produce chlorine.
MnO2 is an alpha polymorph that can incorporate various atoms (and water molecules) in the "tunnels" or "channels" between the manganese oxide octahedrons. People are very interested in α-MnO2 as a possible cathode for lithium-ion batteries.
Manganese 2 oxide is an amphoteric oxide. It is a very stable black powdery solid at room temperature and can be used as a depolarizer for dry batteries. It is often used in the laboratory to produce chlorine by its oxidizing properties and the action of concentrated HCl. Manganese dioxide is a strong oxidant in acidic media. Manganese dioxide is an [MnO₂] octahedron. The oxygen atom is on the top of the octahedron, and the manganese atom is in the octahedron. [MnO₂] octahedrons are connected to form a single or double chain. These chains and other chains co-top to form The tunnel structure of voids, octahedrons hexagonal close-packed, or square close-packed.
Manganese dioxide is an amphoteric oxide, and there is a corresponding salt in the form of a perovskite structure such as BaMnO3 or SrMnO3 (obtained by a compound reaction in a molten alkali system), and manganese tetrachloride is also present.
When manganese dioxide encounters a reducing agent, it is oxidizing. For example, manganese dioxide is heated in a stream of hydrogen to 1400K to obtain manganese oxide; manganese dioxide is heated in a stream of ammonia to obtain brown-black manganese trioxide; the manganese dioxide is reacted with concentrated hydrochloric acid to obtain l chlorine Manganese, chlorine, and water.
When manganese dioxide encounters strong oxidants, it also exhibits reducibility. Suppose manganese dioxide, potassium carbonate, potassium nitrate, or potassium chlorate are mixed and melted. In that case, a dark green melt can be obtained, and the melt can be dissolved in water and cooled to obtain potassium manganate, a compound of hexavalent Manganese.
Manganese dioxide is a strong oxidant in acidic media. It is used as a catalyst in the decomposition of potassium chlorate [KClO3] and the decomposition of hydrogen peroxide (hydrogen peroxide, H2O2).
Due to the strong oxidant, manganese dioxide does not burn by itself but supports combustion and should not be placed with flammable materials.
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Product Performance of Manganese Dioxide MnO2 CAS 1313-13-9:
Physical properties: black amorphous powder or black rhombic crystals. Solubility: Difficult to dissolve in water, weak acid, weak base, nitric acid, cold sulfuric acid, and dissolve in concentrated hydrochloric acid under heating to produce chlorine gas.
Chemical properties: Manganese dioxide is an amphoteric oxide. A corresponding salt is in the form of a perovskite structure such as BaMnO3 or SrMnO3 (obtained by a compound reaction in a molten alkali system). There is also manganese tetrachloride.
When meeting the reducing agent, it shows an oxidizing property. If manganese dioxide is placed in a stream of hydrogen and heated to 1400K to obtain manganese oxide, manganese dioxide is heated in a stream of ammonia to obtain brown-black manganese trioxide; reacting manganese dioxide with concentrated hydrochloric acid produces l chloride Manganese chloride, chlorine, and water.
When it meets strong oxidants, it also shows a reducing property. It is a strong oxidant in an acid medium.
Manganese Dioxide MnO2 Powder
MnO2 | H2O | Fe | Cu | Pb | Ni | Co | Hg | Acid insoluble | sulfate |
92.33% | 2.17% | 65ppm | 0.5ppm | 0.5ppm | 2.0ppm | 2.0ppm | 47ppm | 0.01% | 1.2% |
How is Manganese Dioxide MnO2 produced?
Naturally occurring manganese dioxide contains impurities and a large amount of manganese trioxide. Only a limited number of deposits contain gamma modifiers of sufficient purity to meet the needs of the battery industry.
The production of batteries and ferrites (the two main uses of manganese dioxide) requires high-purity manganese dioxide. The battery needs "electrolytic manganese dioxide," and the ferrite needs "chemical manganese dioxide."
1. Chemical Manganese Dioxide
One method is to start with natural manganese dioxide and then use dinitrogen tetroxide and water to convert it into a manganese (II) nitrate solution. The evaporation of water leaves crystallized nitrates. The salt decomposes at a temperature of 400°C, releasing N2O4 and leaving a pure manganese dioxide residue. These two steps can be summarized as:
MnO2 +N2O4⇌Mn(NO3)2
2. Carbothermal reduction of manganese dioxide
In another method, manganese dioxide is carbothermal reduced to manganese (II) oxide dissolved in sulfuric acid. The filtered solution was treated with ammonium carbonate to precipitate MnCO.
The carbonate is calcined in air to obtain a mixture of manganese (II) and manganese (IV) oxides. To complete the process, the suspension of the material in sulfuric acid is treated with sodium chlorate. The chloric acid formed in situ can convert Mn(III) and Mn(II) oxides into carbon dioxide, releasing chlorine by-products.
3. Manganese epoxide and manganese monoxide
The third method involves manganese epoxide and manganese monoxide. The two reagents are mixed in a ratio of 1:3 to form manganese dioxide:
Mn2O7 + 3 MnO→5 MnO2
Finally, the effect of potassium permanganate on manganese sulfate crystals produces the desired oxide.
2 KMnO4 + 3 MnSO4 + 2 H2O→5 MnO2 + K2SO4 + 2 H2SO4
4. Electrolytic Manganese Dioxide
Electrolytic manganese dioxide (EMD) is used in zinc-carbon batteries with zinc chloride and ammonium chloride. EMD is also commonly used in manganese zinc dioxide rechargeable alkaline (Zn RAM) batteries. For these applications, purity is critical. The production method of EMD is similar to the production method of electrolytic ductile pitch (ETP) copper: manganese dioxide is dissolved in sulfuric acid (sometimes mixed with manganese sulfate), and electricity is applied between the two electrodes. The dissolved MnO2 enters the solution as sulfate and is deposited on the anode.
Applications of Manganese Dioxide MnO2:
Manganese dioxide is a black or brown solid in the mineral pyrolusite, the main ore of manganese and manganese nodules.
The main use of MnO2 is for dry batteries, such as alkaline batteries and zinc-carbon batteries.
MnO2 is also a precursor for pigments and other manganese compounds (such as KMnO4). It is used as a reagent in organic synthesis, for example, for the oxidation of allyl alcohol.
MnO2 is used as a depolarizer for dry batteries, as a catalyst and oxidant in the synthesis industry, and as a colorant, decolorant, and iron removal agent in the glass and enamel industries.
MnO2 is used to manufacture metallic manganese, special alloys, ferromanganese castings, gas masks, and ferrites for electronic materials.
MnO2 can be used in the rubber industry to increase rubber viscosity.
MnO2 is used as a catalyst in chemical experiments:
Used as a catalyst for the decomposition of hydrogen peroxide (hydrogen peroxide) to produce oxygen.
Used as a catalyst when heating potassium chlorate to decompose and produce oxygen.
It reacts with elemental aluminum powder to produce manganese by a thermite reaction.
Use pigments, yellow glass, etc.
React with hot, concentrated hydrochloric acid to produce chlorine.
In the air, it reacts with molten caustic potassium (potassium hydroxide) to produce potassium manganate.
In the decomposition reaction of potassium permanganate, manganese dioxide acts as a self-catalyst for potassium permanganate.
FAQ of Manganese Dioxide MnO2 Powder:
Q: Is MnO2 ionic or covalent?
A: Manganese dioxide (MnO2) is primarily ionic but has some covalent character. The bond between manganese and oxygen is predominantly ionic, with manganese typically forming a +4 oxidation state, but there is also some covalent bonding due to the partial sharing of electrons.
Q: Is manganese dioxide toxic?
A: Yes, manganese dioxide (MnO2) can be toxic. Inhalation of its dust can cause respiratory issues, and prolonged exposure can lead to manganese poisoning, affecting the nervous system. Proper safety measures, such as wearing protective equipment and ensuring good ventilation, are essential when handling MnO2.
Q: What are the uses of manganese oxide?
A: Manganese oxide (MnO2) has various applications. It is used in dry cell batteries, as a pigment in paints and ceramics, in the manufacture of glass to remove color, in water treatment to remove iron and hydrogen sulfide, and in the production of manganese metals and alloys. It is also used in the chemical industry as a catalyst and oxidizing agent.
Manganese Dioxide Properties |
|
Other Names | manganese oxide, MnO2 powder |
CAS No. | 1313-13-9 |
Compound Formula | MnO2 |
Molecular Weight | 86.94 |
Appearance | Black Powder |
Melting Point | 535 °C |
Boiling Point | N/A |
Density | 5.03 g/cm3 |
Solubility in H2O | Insoluble |
Exact Mass | 86.9279 |
Manganese Dioxide Health & Safety Information |
|
Signal Word | Warning |
Hazard Statements | H302 + H332 |
Hazard Codes | Xn, O |
Risk Codes | N/A |
Safety Statements | N/A |
Transport Information | NONH |