Manganese Dioxide

What is Manganese Dioxide?

The formula MnO2 is commonly known as Manganese Dioxide. It is a solid that has a black-brownish colour. Manganese dioxide, when found in nature, is known as pyrolusite. It is considered to be the most plentiful out of all the manganese compounds. Pyrolusite is the principal ore of the compound manganese dioxide. Manganese Dioxide is commonly used for batteries and also as pigment for other Manganese compounds. An impure form of manganese can be obtained by reducing manganese dioxide with carbon. Manganese Dioxide is the inky quadra positive manganese compound. 


MnO2 compound name is given as dioxo manganese. It is a certain MnO2 chemical name. 


Where is Manganese Dioxide Found?

The most common Manganese bearing minerals are Pyrolusite and Rhodochrosite. These are the basic sources of manganese dioxide in nature. Moreover, manganese dioxide and the other manganese compounds are found on the ocean floors too. The countries which supply the maximum Manganese are Brazil, USSR, Russia, India, Africa, Australia and New Zealand. The primary way in which manganese is produced is by the reaction of the oxides with sodium, aluminium and magnesium. Chemically in the laboratories, it is produced by electrolysis. Manganese is present in four different forms. One form is stable in room temperature and is known as alpha form. 


Chemical Properties of Manganese Dioxide 

Chemical Formula: MnO2

Molar Mass: 86.9368 g/mol

Appearance: Brown - black solid

Density: 5.026 g/cm3

Manganese Dioxide Melting Point: 535 °C

Covalently Bonded Unit: 1

Solubility in Water: Insoluble 


Physical Properties of Manganese Dioxide

Odour: Odourless 

Appearance: Brown - Blackish solid

Complexity: 18.3 

MnO2 Oxidation Number: +4

Solubility: Insoluble in water 

Hydrogen Bond Acceptor: 2


Properties of Manganese Dioxide

  • Magnesium dioxide is abundantly used in the ceramic industry. All the raw materials used in the making of glass contain some amount of iron. This iron is usually in the form of ferric oxides. The use of manganese dioxide in such industries is highly beneficial and practical. 

  • Manganese ores are again commonly used in dry cell batteries. Many of these cells need to be activated by physical or chemical means. These means are manufacturing techniques that need special machinery and work at certain temperatures only. 

  • Glass often gets a tint due to the presence of impurities. Manganese dioxide gets rid of the green tint produced as a result of the various iron impurities. 

  • The positive electrode carbon in batteries is secure indeed by a layer of magnesium dioxide. Carbon is also present around It. 

  • A majority of manganese dioxide is used in the steel industry. Manganese is basically used in the deoxidation of steel. 

  • The black-brown pigments present in paint are basically manganese dioxide. 

  • Soft drink cans also have a specific alloy present in them. This alloy is made from manganese dioxide. 


Solved Examples: 

Manganese Dioxide as a Catalyst:

Oxygen is produced in the laboratory in the presence of hydrogen peroxide and manganese dioxide. Manganese dioxide here acts as a catalyst and accelerates the reaction. 


2H2O2(aq) → 2H2O(l) + O2(g)


Here manganese dioxide is the accelerant. When manganese dioxide is added to hydrogen peroxide, bubbles of oxygen are produced. 


3MnO2 (s) + 4Al (s) → 3Mn (I) + 2Al2O3 (s)


Manganese Dioxide Reacting With Potassium Chlorate

Potassium chlorate (KClO3) is heated in the presence of manganese dioxide catalyst and it decomposes to form potassium chloride and oxygen gas. 

The balanced chemical equation is: 


2KClO3 → 2KCl + 3O2


The above is the laboratory process of oxygen generation. The chemically produced oxygen is suitable for usage immediately. It has to go through a few more filtration processes. 


Manganese Dioxide Reacting With Aluminium

Manganese dioxide , when reacted with aluminum, gives metallic manganese and aluminum oxide. Along with this, a lot of heat is generated. It is an exothermic reaction as the change in enthalpy comes out to be negative. 


MnO2 + Al → Al2O3 + Mn 


Fun Facts About Manganese and Manganese Dioxide

  • Manganese was first discovered in the year 1774. 

  • Historically it has been seen that cave paintings in the Stone Age contained manganese pigments. 

  • Manganese has a very prevalent look to that of iron. In contrast to Iron it has a silver - grey colour. 

  • It Is well known that iron rusts the most, but Manganese rusts as much as iron only. In fact research has shown that at times, manganese rusts more than iron too sometimes. 

  • Manganese dioxide is present abundantly In nature. 

  • The most common uses of manganese dioxide are production of stainless steel, glass industry, paint industry and more. 

  • Manganese is found in the mitochondria for functioning of living cells. Mitochondria, also known as the powerhouse of the cell, depends on manganese for proper functioning of the human cell body. 

  • Most of the manganese Is present in the skeleton of the human body. 

  • Although manganese is not toxic in a light amount, a handful of manganese usage can prove to be lethal.

FAQ (Frequently Asked Questions)

1. Is Manganese Dioxide Toxic for the Human Body?

Ans: It is often said that Manganese dioxide is a highly toxic compound for the human body. Inhalation of the compound can lead to chronic diseases. It is often said that the manganese miners who work very closely around manganese and its compounds suffer from various respiratory problems over the time. Although the exact toxicity of manganese is debatable, it is best to use some kind of protective gear before working on manganese compounds. Too much manganese inhalation is neurotoxic. Manganese causes syndromes such as weakness, headaches, insomnia and headaches too. Parkinson’s Is a common neurological disorder caused due to manganese.

2. How does the Human Body Receive Manganese?

Ans: Humans receive manganese through food, tea and various other herbs. Some amount of manganese Is also present in rice, soya, green beans, olive, eggs and more. Manganese after absorption is transported to the endocrine glands through the pancreas In the human body. The most common part that manga sees affect is the human brain and the central nervous system. The respiratory tract is also affected majorly by the intake of manganese. On the other hand,  the shortage of manganese is also not very beneficial for a healthy human body. Lack of manganese can lead to glucose intolerance and low cholesterol levels.