Pyrolusite or MnO 2, a common mineral present in the earth’s crust, is the main source of the metal manganese. In the +4 state, manganese form stable dioxide MnO 2, halide MnF 4, and the complexes MnX 6 −2, where X = fluorine, chlorine, cyanide, and IO 3. The green mass is extracted with water containing little alkali and the solution evaporated to yield dark green crystalline solid K 2MnO 4. It is obtained as a green mass by fusing pyrolusite with alkali. Manganate ion (MnO 4 −2) is the only suitable representative in the +6 state of manganese. The green oxide is highly explosive that ignites alcohol or ether when brought into contact. In the +7 state, the metal forms oxide like Mn 2O 7 and oxohalides MnO 3Cl and MnO 3F. Potassium permanganate is used as an oxidizer in analytical chemistry. Permanganate ion is a very strong oxidizing agent in acid solution and moderately strong in the neutral and alkaline medium. Permanganate is familiar to us due to its strong oxidizing properties. Potassium permanganate is an important compound of manganese having the chemical formula KMnO 4. The reduction potential oxidation state diagram suggests that Mn (VI) is a highly oxidizing agent, that oxidizes to form Mn (III) and Mn (IV) ions. The +2 oxidation state is most stable due to the presence of a half-filled d 5 electron configuration. The acids are reduced to form sulfur dioxide and nitrogen monoxide (NO). It liberated hydrogen from all dilutes acids, including dilute nitric acid. The greyish-white paramagnetic metal, manganese does not oxidize in a very pure form but the presence of impurities like carbon makes it more reactive. The Mn (II) sulfate was further purified by crystallization before subjecting electrolysis. In both techniques, manganese sulfate (MnSO 4) is leached out from the residue by leaving impurities like iron oxide and other silicate compounds. The element, manganese is produced by electrolysis of an aqueous solution of Mn (II) sulfate which is prepared from pyrolusite by heating concentrated sulfuric acid at 150 ☌.Īlternatively, pyrolusite is heated below 800 ☌ with dehydrated green vitriol. 55Mn (half-life = 3.7 million years) and 54Mn (half-life = 312.2 days) are the most stable isotopes of Mn. The radioactive isotopes of Mn are obtained from different types of nuclear reactions. It has several radioactive isotopes with atomic mass ranges from 44 to 69. Naturally, occurring manganese has one stable isotope with an atomic mass of 55. The transition element, manganese present in food plants and animal bodies and plays an important role in the biological process. The large deposit of the elements may gain commercial significance in the future. More than 10 12 tones of such nodules have already been accommodated from the ocean water bed. It contains 15 to 30 percent of metal on a dry basis with copper, nickel, and cobalt. Manganese is found in a variety of minerals like pyrolusite (MnO 2) Hausmannite (Mn 3O 4), Braunite (Mn 2O 3) Manganese spar (MnCO 3) in Russia, India, South Africa, Ghana, Brazil, and Chile.Ĭolloidal particles of manganese are found on the ocean floor to form compact Mn nodules. It is the third most abundant transition metal after iron and titanium and the twelfth most abundant element among all periodic table elements. Manganese is a member of a transition metal that possesses the outer orbital electronic configuration 3d 5 4s 2. It is placed in group 7 and period 4 with d-block elements in the periodic table. The Latin magnes means magnet or from the black magnesium oxide magnesia nigra The +6 oxidation number or state is familiar to us in the compound potassium permanganate, KMnO 4, a strong oxidizing agent. The melting point and density of manganese are much lower than those of chromium suggesting more participation of d- electron in metallic chemical bonding. It formed a body-centered cubic crystal lattice. The metal was named in the Latin word magnesium from the old name pyrolusite. In chemistry, the element was isolated by another Swedish chemist Johan Gottlieb Gahn and studied by the Swedish chemist Carl Wilhelm Scheele in 1774. The Swedish chemist Bergmann discovered the presence of manganese in the black magnesia but fails to isolate it.
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