How do you find the Oxidation State of MnO2?

Read our article where we explain everything related to the MnO₂ oxidation state and basic theory to understand this topic.

Introduction:

Before we explain MnO₂ oxidation and related concepts, let’s quickly review the related concepts to build a foundation for this article. First, oxidation number and oxidation states are commonly discussed concepts that act as the backbone of all theoretical and practical implications in both organic and inorganic chemistry. Both are commonly taken as the same terms, but they have a slight difference in their meaning.

When we talk about the oxidation state, it is the apparent charge of an atom that it has when being in a compound’s molecular structure. Oxidation number, on the other hand, is a hypothetical number that denotes the total number of electrons gained or lost by a specific atom for which oxidation number is being expressed. This takes the assumption that in this state, all the participants in a molecule are acting as fully ionic sub-components.

Depending on how many electrons are being lost or gained, this number can vary while being positive, negative, or even zero. The difference between them is that the Oxidation state is the charge on an atom in a molecule and the oxidation number is a specific value of that charge denoted by a positive or negative number.

Coming back to Manganese (Mn) and its oxide, Manganese Oxide (MnO₂) is an inorganic compound that also happens to be the most common source of manganese. With the appearance of having black-brown color in solid form, it is commonly used in pigments, and batteries (zinc-carbon and alkaline batteries), and acts as a precursor for many alloys. 

The Oxidation of Manganese Oxide

Manganese can have different oxidation states due to its electronic configuration of [Ar] 3d^5 4s^2 where it has multiple electrons present in this outer shell i.e. 3d and 4s shells. The electrons in these shells can be given away or more can join in with them to attain stability. This gives the atoms of Manganese different oxidation numbers. These include +2 oxidation number which results when 4s^2 electrons are given away forming compounds like manganese(II) chloride (MnCl₂). It can also have +3, +4, and +7 when it loses more electrons.

Its oxide, MnO₂ has one manganese atom bound with two oxygen atoms which, manganese, again has lost its four electrons to bound with two Oxygen atoms (2 for each). Thus, the oxidation state of mn in MnO₂ is a positively charged ion with an oxidation number of +4 in this particular molecule. MnO₂ oxidation can be conducted with alcohols to convert them into aldehydes or ketones.

Note that when stating the MnO₂ oxidation number, it can be seen that the net charge in the molecule is balanced among the two types of elements so the oxidation number of MnO₂ just like any other stable molecule is zero. The oxidation number of Mn is +4 in the molecule which is balanced by the oxidation number of oxygen which is -2 in this case. So, for two Oxygen atoms, the total negative charge is -4 which cancels out the positive charge on the Manganese side.

Also, it is worth mentioning that MnO₂ is a higher oxide of manganese which means that this bonding has two bonds between the Mn and oxygen atoms. On peroxides, the bond between Oxygen and the other element is a single bond giving an oxidation number of -1 to oxygen. In the case of MnO₂, it is -2 making it a higher oxide of manganese.

The ability of manganese to readily give away valence electrons makes it a great choice to be used in the cathode material of alkaline batteries where it acts as a fantastic medium for high electrical conductivity. Other common uses include its role in water treatment, glass formulations to impart final gas color, vehicle catalytic converters, and for production of resistors and capacitors, thus acting as an important element for electronics.

Conclusion:

Just like any other molecule, the MnO₂ oxidation is zero as it is balanced. While the oxidation number is +4 and -2 for manganese and Oxygen in this molecule.