KMnO4 in alkaline medium changes to MnO2.

Explanation:
1. Introduction:
Potassium permanganate (KMnO4) is a strong oxidizing agent that can undergo various reactions depending on the conditions. In an alkaline medium, KMnO4 undergoes a specific change to form manganese dioxide (MnO2).

2. Reaction:
The reaction can be summarized as follows:
2KMnO4 + 2KOH → MnO2 + 2K2MnO4 + H2O

3. Alkaline medium:
In an alkaline medium, the solution contains a base such as potassium hydroxide (KOH). The presence of the base helps in the formation of the desired product, MnO2.

4. Mechanism:
The reaction proceeds through a series of steps:
- The alkaline medium causes the oxidation of MnO4- ions to MnO2.
- The MnO4- ions are reduced to MnO2 by accepting electrons from the OH- ions in the alkaline solution.
- This reduction process leads to the formation of MnO2 as the final product.

5. Result:
The final product of the reaction is manganese dioxide (MnO2). It is a black solid with various applications, including as a catalyst, in batteries, and in the production of chlorine.

6. Other products:
During the reaction, some other products are also formed, such as potassium manganate (K2MnO4) and water (H2O). These by-products are formed due to the redox reactions occurring between the KMnO4 and KOH.

7. Importance:
The conversion of KMnO4 to MnO2 in an alkaline medium is an important reaction in various fields. It is used in organic chemistry for the synthesis of specific compounds and in analytical chemistry for the determination of reducing agents.

In conclusion, when KMnO4 is placed in an alkaline medium, it undergoes a reaction that results in the formation of manganese dioxide (MnO2). This reaction is important in various applications and is mediated by the reduction of MnO4- ions to MnO2 in the presence of OH- ions.

Mn(OH)4