Question

Potassium permanganate is purple in colour. On adding KOH, it turns green. What is the compound formed?
A. Potassium permanganate
B. Potassium manganate
C. Both A and B
D. None of the above

Answer 1

Hint: Potassium permanganate ($KMn{O_4}$) is a dark purple coloured and odourless compound. Potassium permanganate is a strong oxidising agent.
Potassium permanganate ($KMn{O_4}$) is an odorless solid, and they look like crystals of dark purple or bronze color. When these crystals are dissolved in water, the solution becomes purple in color.
Complete step-by-step answer:
Physical Properties of Potassium Permanganate:
It is an odorless, purple to magenta crystalline solid.
It is soluble in water, acetone, acetic acid, methanol, and pyridine.
It gets dissolved in ethanol and organic solvents.
Potassium permanganate is found in the form of monoclinic prisms, which are almost opaque with a blue metallic light.
It is odorless. An aqueous solution has a sweetish astringent taste. It is water-soluble and more soluble in boiling water.
Chemical Properties Of Potassium Permanganate:
Potassium permanganate is a very strong oxidizing agent and can, therefore, be used as an oxidant in a wide spectrum of chemical reactions.
We can see the oxidizing capability of potassium permanganate while performing a redox reaction with it, in which the dark purple solution turns colorless and then into a brown solution.
The above reaction can be performed in an acidic or a basic medium.
Now the reaction between potassium permanganate and potassium hydroxide gives:
$2KMn{O_4} + 2KOH \to 2{K_2}Mn{O_4} + {H_2}O + \dfrac{1}{2}{O_2}$
Thus the purple coloured potassium permanganate reacts with KOH to form green coloured potassium manganate.
Hence option B is the correct answer.

Note: Potassium permanganate is used to treat various skin diseases such as fungal infection in the foot, it is also used as an oxidizing agent in industries since it is a powerful oxidizing agent.