Preparation of potassium permanganateपोटैशियम परमैंगनेट का निर्माणPreparation of potassium permanganate

Class 12 Chemistry · Chapter 4 · interactive diagram

Parts and what they mean

• Pyrolusite, MnO₂ (पाइरोलुसाइट, MnO₂) — The manganese ore; Mn is +4.
• Alkaline oxidative fusion (क्षारीय ऑक्सीकारी संगलन) — 2MnO₂ + 4KOH + O₂ → 2K₂MnO₄ + 2H₂O (Mn +4 → +6).
• Potassium manganate (green) (पोटैशियम मैंगनेट (हरा)) — Dark green K₂MnO₄; MnO₄²⁻ is tetrahedral and paramagnetic (d¹).
• Disproportionation (neutral or acid) (असमानुपातन (उदासीन या अम्ल)) — 3MnO₄²⁻ + 4H⁺ → 2MnO₄⁻ + MnO₂ + 2H₂O. Mn(+6) → Mn(+7) + Mn(+4).
• Commercial: electrolytic oxidation (व्यावसायिक: विद्युत-अपघटनी ऑक्सीकरण) — Manganate(VI) is oxidised electrolytically in alkaline solution to permanganate(VII): MnO₄²⁻ → MnO₄⁻ + e⁻.
• Potassium permanganate (purple) (पोटैशियम परमैंगनेट (बैंगनी)) — Dark purple crystals; MnO₄⁻ is tetrahedral and diamagnetic (d⁰).
• Laboratory route (प्रयोगशाला विधि) — 2Mn²⁺ + 5S₂O₈²⁻ + 8H₂O → 2MnO₄⁻ + 10SO₄²⁻ + 16H⁺ (balanced: charge −6 on both sides).

Steps

1. Start with pyrolusite and fuse it with KOH in air (or with KNO₃).
2. Green potassium manganate, K₂MnO₄, forms.
3. Manganate → permanganate: disproportionation in neutral/acid solution, or (commercially) electrolytic oxidation.
4. In the laboratory, Mn²⁺ is oxidised by peroxodisulphate.

Original diagram drawn by Simple Learning Hub, based on the NCERT textbook. Report a mistake