Inorganic chemistry / by Ira Remsen.

  • Remsen, Ira, 1846-1927
Date:
1889
Catalogue details

Licence: Public Domain Mark

Credit: Inorganic chemistry / by Ira Remsen. Source: Wellcome Collection.

    717/866 (page 685)
    CHAPTER XXXIII. ELEMENTS OF FAMILY VIII, SUB-GROUP A: IRON—COBALT—NICKEL. General.—The three elements which form this group are in many respects very similar, and their atomic weights differ but little from one another. That of iron (55.88) is nearly the same as that of manganese (54.8), while cobalt and nickel have nearly the same atomic weight. There is much in iron which suggests manganese. It forms two series of compounds, the ferrous and ferric compounds, which are analogous to the manganous and manganic compounds. In the first series iron appears to be bivalent, as shown in the formulas FeCl2, Fe(OH)2, FeO, FeS, FeS04, FeC03, etc. In the second series it appears to be trivalent, as indi- cated in the formulas FeCl3, Fe(OH)s, Fe20„ Fe(N03)3, Fe3(S04)„ etc. Like chromium and manganese it also forms an acid known as ferric acid, H2Fe04, which in composition is analogous to chromic and manganic acids. The soluble salts of this acid are, however, unstable, and on decom- posing yield ferric hydroxide. Oxidizing agents readily convert ferrous compounds into ferric compounds, and reducing agents reconvert the latter into the former. When exposed to the air most ferrous compounds are oxidized to ferric compounds. The ferrous compounds in which iron is bivalent are similar to the compounds of the zinc group. The ferric compounds, however, in which the iron is trivalent, are similar to the aluminium compounds ; and in ferric acid it exhibits a resemblance to chromium. Cobalt and nickel resemble iron in re-