Why potassium permanganate is not a primary standard?

Question

Accepted Answer

Potassium permanganate is not a primary standard due to its instability and tendency to react with impurities.

Potassium permanganate is highly reactive and can easily react with impurities in the air or solution, leading to inaccurate results.
It is also unstable and can decompose over time, making it difficult to maintain a consistent concentration.
Primary standards are highly pure and stable substances that can be accurately weighed and dissolved to prepare a standard solution.
Examples of primary standards include sodium chloride, potassium hydrogen phthalate, and oxalic acid.
Potassium permanganate is often used as a secondary standard for redox titrations, where it is standardized against a primary standard.