I. Basic Information
Manganese Dioxide is a common inorganic compound. In nature, it exists in the form of pyrolusite and is one of the most important oxides of manganese. Its molecular weight is 86.94, and its CAS registry number is 1313 - 13 - 9.
II. Physical and Chemical Properties
- Appearance: Usually, it is a black or dark brown powder or block solid. It presents the typical characteristics of metal oxides, insoluble in water and most organic solvents.
- Oxidizing Property: It has strong oxidizing properties and can exhibit variable oxidation states in different chemical reactions. For example, when reacting with concentrated hydrochloric acid, manganese dioxide acts as an oxidant, oxidizing chloride ions in hydrochloric acid to chlorine gas, and it is reduced to divalent manganese ions.
- Stability: Under normal temperature and pressure, manganese dioxide has good chemical stability. However, under high temperature or specific chemical reaction conditions, it will participate in reactions and undergo chemical changes. For example, under heating conditions, manganese dioxide can react with some reducing agents such as carbon and hydrogen.
III. Preparation Methods
- Chemical Precipitation Method: Soluble manganese salts (such as manganese sulfate) react with precipitants (such as sodium hydroxide, sodium carbonate, etc.) to first form manganese hydroxide precipitate, and then it is oxidized to obtain manganese dioxide. Taking the reaction of manganese sulfate with sodium hydroxide as an example, manganese hydroxide precipitate is first formed. Then, the manganese hydroxide precipitate is oxidized in the air or with an oxidant (such as hydrogen peroxide), and finally manganese dioxide is obtained.
- Electrolysis Method: Using manganese sulfate solution as the electrolyte, manganese dioxide is generated on the anode through electrolysis. During the electrolysis process, manganese ions lose electrons at the anode and are oxidized to manganese dioxide.
IV. Application Fields
- Battery Industry: It is a key cathode material for primary batteries such as zinc - manganese batteries and alkaline zinc - manganese batteries, as well as secondary batteries such as lithium - ion batteries. In zinc - manganese dry batteries, manganese dioxide, as the positive active material, participates in the discharge reaction of the battery. The reaction process is relatively complex. Generally, during the discharge process, manganese dioxide gains electrons and undergoes a series of chemical reactions with ammonium ions, etc., thereby generating an electric current to provide electrical energy for electrical appliances.
- Chemical Industry: It is commonly used as an oxidant and catalyst. In organic synthesis, it can be used to oxidize alcohol compounds to aldehydes or ketones. For example, under mild conditions, manganese dioxide can selectively oxidize allyl alcohol to the corresponding allyl aldehyde. In some chemical reactions, such as the decomposition of potassium chlorate to prepare oxygen, manganese dioxide acts as a catalyst, which can reduce the activation energy of the reaction and accelerate the reaction rate, enabling potassium chlorate to decompose rapidly to produce oxygen at a lower temperature.
- Glass and Ceramic Industries: It can be used for the decolorization of glass and the coloring of ceramics. In the glass manufacturing process, some impurity iron ions in the glass raw materials can make the glass appear green or other colors. Adding an appropriate amount of manganese dioxide can oxidize these low - valence iron ions to high - valence iron ions, thereby changing the color of the glass and achieving the purpose of decolorization. In the ceramic industry, manganese dioxide can be used as an important coloring agent. Depending on its addition amount and firing conditions, ceramics can present different colors such as brown and black.
| Product name: |
Manganese dioxide |
| Appearance: |
Black powder |
| CAS No.: |
1313-13-9 |
| EINECS No.: |
215-202-6 |
| Molecular formula: |
MnO2 |
| Molecular weight: |
86.94 |
| Density: |
5.02 |
| Melting point: |
535 °C |
| water-solublility: |
insoluble |
| Storage Conditions: |
Store below +30°C. |
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