|OTP appearance||brown/black solid|
|Solubility in water(g/L)||insoluble|
- Essential for several kinds of voltaic cells
- As an oxidizer for producing both potassium permanganate and chlorine
- Source of pure manganese via carbothermal reduction
- Manganese dioxide occurs naturally as pyrolusite
Manganese dioxide is purified from the raw material (pyrolusite) by dissolving the pyrolusite in a solution of sulfuric acid, sometimes adulterated with manganese sulfate. A current is applied, and the purified manganese dioxide is deposited on the anode.
- Crush psilomelane to a fine powder
- Dissolve in dilute (but proportional) hydrochloric acid, producing some chlorine gas.
- MnO2 + 4 HCl → MnCl2 + 2 H2O + Cl2
- Discard residue
- Precipitate the iron chloride by converting it to prussian blue
- Retain residue of prussian blue
- Evaporate filtrate
- Roast residue, producing manganese dioxide and chlorine gas, leaving the other (sodium, potassium, barium) chlorides unchanged.
- Wash with water
- Residue is manganese dioxide
- Filtrate contains assorted chlorides.