MCQ Detailed View

Manganese oxides exhibit a variety of chemical behaviors depending on their oxidation states. Among them, manganese dioxide (MnO₂) is amphoteric, which means it can react with both acids and bases.

In acidic conditions, MnO₂ reacts with strong acids such as HCl or H₂SO₄ to produce manganese(II) salts and chlorine or oxygen depending on the reaction:

MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O

In basic conditions, MnO₂ reacts with strong bases like sodium hydroxide (NaOH) in the presence of an oxidizing agent to form manganates:

2MnO₂ + 4NaOH + O₂ → 2Na₂MnO₄ + 2H₂O

Other oxides of manganese are not amphoteric:

• 
  

  Mn₂O₃ is mainly basic.

  
  


• 
  

  Mn₂O₇ is strongly acidic.

  
  


• 
  

  MnO is basic.

  
  

The amphoteric nature of MnO₂ is significant in inorganic chemistry because it demonstrates how oxidation states affect chemical reactivity. MnO₂ is widely used as an oxidizing agent, in the manufacture of batteries, and in industrial chemical reactions.

Understanding amphoterism helps students relate metal oxides, acid-base reactions, and redox chemistry, which are key concepts in the study of inorganic compounds and transition metals. Recognizing that MnO₂ can act both as a base and an acid illustrates the versatile chemical behavior of transition metal oxides.