When potassium permanganate (KMnO₄) is mixed with sodium hydroxide (NaOH), a chemical reaction occurs that results in the formation of various compounds, depending on the concentration and conditions of the reaction. The main products in this reaction are potassium manganate (K₂MnO₄), water (H₂O), and the release of heat. This reaction is a good example of how the oxidation states of elements can change in chemical processes.

The Chemical Reaction

When potassium permanganate (KMnO₄), which is purple in color, is added to sodium hydroxide (NaOH), the manganese ion (Mn) in KMnO₄ undergoes a reduction in its oxidation state. In basic conditions (provided by NaOH), the purple color of KMnO₄ disappears as it transforms into a green compound called potassium manganate (K₂MnO₄).

The balanced chemical equation for the reaction is:

2K₂MnO₄+2NaOH→2K₂MnO₄+H₂O+O₂

In this reaction:

• Potassium permanganate (KMnO₄) is reduced to potassium manganate (K₂MnO₄).
• Sodium hydroxide (NaOH) serves as the base that provides hydroxide ions (OH⁻) to the reaction, aiding in the transformation.
• Oxygen gas (O₂) is also released during the reaction as a by-product.

What Are the Products?

1. Potassium Manganate (K₂MnO₄):
   This compound is green in color, in contrast to the deep purple color of potassium permanganate. It is a manganese(VI) compound where manganese has an oxidation state of +6. Potassium manganate is commonly used as a strong oxidizing agent in various chemical processes.
2. Water (H₂O):
   Water is formed as a result of the combination of hydroxide ions (OH⁻) from sodium hydroxide and the manganese species in potassium permanganate.
3. Oxygen Gas (O₂):
   Oxygen gas is produced during this reaction, typically as a by-product due to the oxidation of manganese species. The oxygen comes from the breakdown of KMnO₄ under basic conditions.

Oxidation and Reduction in the Reaction

This reaction is an example of redox chemistry (reduction-oxidation). In this case:

• Potassium permanganate (KMnO₄) undergoes reduction as manganese changes from an oxidation state of +7 in KMnO₄ to +6 in K₂MnO₄.
• The hydroxide ion (OH⁻) from NaOH is oxidized, providing oxygen gas (O₂) as a by-product.

Conditions Affecting the Reaction

1. Concentration:
   The concentration of NaOH and KMnO₄ can affect the extent of the reaction and the color of the products. At lower concentrations, the green potassium manganate may be less intense, and some potassium permanganate may remain unreacted.
2. Temperature:
   The temperature of the reaction mixture can influence the speed of the reaction and the amount of oxygen gas produced. Heat may also affect the stability of the manganese species.

Applications of the Reaction

• In Analytical Chemistry:
  Potassium permanganate is used as an oxidizing agent in titrations to determine the presence of reducing agents. When mixed with NaOH, the color change from purple to green can be used to track the progress of chemical reactions.
• In Industrial Applications:
  Potassium manganate is used in various oxidation processes, including water treatment and in the manufacture of dyes and chemicals.

When KMnO₄ (potassium permanganate) is mixed with NaOH (sodium hydroxide), the reaction primarily produces potassium manganate (K₂MnO₄), water, and oxygen gas. The color change from purple to green indicates the reduction of manganese from the +7 oxidation state to +6. This reaction highlights important principles in redox chemistry and has applications in both laboratories and industrial processes.