MnO2 and CuO are inorganic compounds which have a similar appearance, existing as blackish-brown solids at room temperature. Therefore, it is very difficult to distinguish these two solid compounds just by looking at them, so we need different experimental procedures to identify them separately. As a basic difference, they have different chemical compositions; MnO2 has manganese in its oxide form while the CuO compound has copper in its oxide form, which has the copper in +2 oxidation state.
What is MnO2?
MnO2 is manganese(IV) oxide which has manganese in +4 oxidation state. It appears as a blackish-brown solid at room temperature. Naturally, it occurs in the mineral form pyrolusite. The preferred IUPAC name for this compound is manganese(IV) oxide. The molar mass of MNO2 is 87 g/mol. It is a water-insoluble solid. There are several applications of MnO2. It is mainly useful as a component in dry cell batteries. Also, it is important in organic synthesis as an oxidant.
There are several known polymorphs and hydrated forms of MnO2. Moreover, this compound crystallizes in the form of a rutile crystal structure. It has an octahedral metal centre and three coordinated oxides.
There are two possible production methods of manganese dioxide (MnO2); they are the chemical method and electrolytic method. The chemical method begins with natural manganese dioxide, which has impurities. We have to convert this natural MnO2 into manganese(II) nitrate using dinitrogen tetroxide with water. Upon heating, the nitrate salt evaporates, releasing N2O4, and we can observe the remaining manganese dioxide, which is in the pure form. The electrolytic method is also a useful method in the production of MnO2. Here, pure manganese dioxide deposits on the anode.
What is CuO?
CuO is copper(II) oxide. It has copper in +2 oxidation state. It appears as a blackish-brown solid at room temperature. It is one of the two most stable oxides of copper. In nature, copper oxide occurs in a mineral form called tenorite. The IUPAC name of this compound is copper(II) oxide. The molar mass is 79.5 g/mol. It is water-insoluble. Moreover, it has a monoclinic crystal structure. Here, one copper atom associates with four oxygen atoms in a square-planar geometry.
Pyrometallurgy is the method we commonly use for the production of CuO. Here, we can extract copper oxide from its ore. In this process, we need to treat the ore with a mixture of aqueous ammonium carbonate, ammonia and oxygen. This treatment initially gives copper(I) and copper(II) ammine complexes. Then we can decompose these complexes in order to get pure CuO. Moreover, we can produce this compound via heating copper metal in the presence of oxygen as well.
What are the Similarities Between MnO2 and CuO?
- Both MnO2 and CuO have the same appearance of blackish brown colour, and they exist in the solid phase at room temperature.
- These compounds are insoluble in water.
What is the Difference Between MnO2 and CuO?
The key difference between MnO2 and CuO is that MnO2 is the oxide of manganese, whereas CuO is the oxide of copper. Furthermore, in MnO2, the metal atom is in +4 oxidation state, while in CuO, the metal atom is in +2 oxidation state.
Moreover, another difference between MnO2 and CuO is that MnO2 has a rutile crystal structure, while CuO has a monoclinic structure.
Summary – MnO2 vs CuO
Both MnO2 and CuO have the same appearance of blackish brown colour, and they exist in the solid phase at room temperature. The key difference between MnO2 and CuO is that MnO2 is the oxide of manganese, whereas CuO is the oxide of copper.
1. Helmenstine, Anne Marie. “Manganese Facts.” ThoughtCo, Jul. 3, 2019, Available here.
1. “Manganese(IV) oxide” By Walkerma assumed – No machine-readable source provided. Own work assumed (based on copyright claims) (Public Domain) via Commons Wikimedia
2. “CopperIIoxide” By User Walkerma on en.wikipedia, Public Domain) via Commons Wikimedia