The starting material for the manufacture of \[\;KMn{O_4}\] is: (A) Pyrolusite (B) Manganite (C) Magnetite (D) Haematite
Answer
Verified
Hint: Potassium permanganate is produced industrially from manganese dioxide which occurs as mineral pyrolusite. The \[\;Mn{O_2}\] is fused with potassium hydroxide and heated in air or with another source of oxygen, like potassium nitrate or potassium chlorate.
Complete step by step solution: The starting material for the manufacture of \[\;KMn{O_4}\] is pyrolusite. Pyrolusite is a mineral consisting essentially of manganese dioxide (\[Mn{O_2}\]) and is important as an ore of manganese. It is a black, amorphous appearing mineral, often with a granular, fibrous, or columnar structure, sometimes forming uniform crusts. It consists of manganese ions and oxide ions. Potassium permanganate is prepared by fusion of \[Mn{O_2}\](pyrolusite) with potassium hydroxide and an oxidizing agent like \[KN{O_3}\] to form potassium manganate (green mass), which disproportionate in a neutral or acidic solution to form permanganate. \[3{K_2}Mn{O_4} + 4HCl \to 2KMn{O_4} + Mn{O_2} + 2{H_2}O + 4KCl\]
Hence, option A is correct.
Note: \[\;KMn{O_4}\] is a strong oxidizing agent with Mn in +7 state. In an acidic medium there is a change of 5 electrons whereas in neutral and basic medium it will act as an oxidizing agent.
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