A text-book of inorganic chemistry / by George Senter.

  • Senter, George, 1874-
Date:
1913
Catalogue details

Licence: In copyright

Credit: A text-book of inorganic chemistry / by George Senter. Source: Wellcome Collection.

    564/678 (page 550)
    On account of their powerful oxidizing action, permangates are largely used as disinfectants. The cheaper sodium permanganate, which does not readily crystallize, is sold in solution for this purpose under the name of Condfs disinfecting fluid. The action is identical with that of the potassium salt, being due to the MnO/ ion. Tests for Manganese—The formation of a flesh-coloured sulphide, MnS, when ammonium sulphide is added to the solution of a manganous salt is a characteristic test; the sulphide is soluble in acetic acid. Further, the formation of a green mass of manganate when a salt of manganese is fused with alkali and an oxidizing agent is a useful test; when the green mass is treated with water and the solution is boiled, it becomes pink. Manganese salts give an amethyst colour to a borax bead. Summary—Owing to the isolated position of manganese in the periodic table, there are no elements which very closely resemble it ; but, on the other hand, it shows a number of points of analogy with elements belonging to other groups. The remarkable variety of valencies shown by manganese has already been mentioned ; it acts as a divalent, trivalent, hexavalent, septavalent, and possibly quadri- valent element. In the divalent manganous compounds it re- sembles magnesium and ferrous salts, the compounds MnS04,7H20, MgS04,7H20 and FeS04,7H20 being isomorphous; in its trivalent compounds it resembles iron and aluminium, as is clearly shown by the existence of a manganese alum, Mn2(S04)3,K2S04,24H20 ; in its sexavalent compounds it resembles sulphur and chromium, as is shown by the isomorphism of the compounds K2Mn04, K2S04 and K2Cr04 ; finally, in its septavalent compounds it resembles the highest oxidation stage of chlorine, the compounds KMn04 and KC104 being isomorphous. It follows that the formula of potassium manganate is represented graphically thus : /OK 0X0K , and potassium per- manganate thus: ),Mn{ (X \QK It is interesting to note that the green manganate ion and the red permanganate ion are both of the composition Mn04, but the former has two negative charges, the latter only one.