A Short Manual of Analytical Chemistry, Qualitative and Quantitative--Inorganic and Organic (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 edition. Excerpt: ... There are almost unlimited cases in which such solutions may be applied to the various bodies capable of undergoing a definite change by oxidation, but the most common applications are: --. (1) For the estimation of ferrous salts. If we look at the simplest equation for the transference of iron from the ferrous to the ferric state, we find 2FeO + 0 = Fe203. So we observe that 1 atomic weight of O can oxidize 2 atomic weights of Fe, or that 7-94=Fe 55-5; 1, w .. molecular weight therefore each Cc. of-fir ox1dant =-005 s 5 metall1c 1ron or lu JJJ 10,000 of any ferrous salt containing 1 atom of iron in its molecule. Either of the oxidants may be employed for the estimation of ferrous salts. Take, for example, crystallized ferrous sulphate. We have the equations: --With bichromate. K2Cr 07 + 6FeS04. 7 H20 + 7H2S04 = 3Fe2(S04)3 + K3S04 + Cr2(S04)3 + 49HP. With permanganate. K2Mn2Os t 1oFeS04. 7H20 + 8H2S04 = 5Fe., (S04)3 + K2S04 + 2MnS04 + 78H20. In certain ferrous salts, such as phosphate or arseniate, the molecules of which contain Fe3, it is evident that from the equation K, Cr207 + 2Fe3(As04)2 + 7H2S04 = Fe., (S04)3 + 2Fe2(As04)2 + igS04 + Cr2(S04)3 + 7Hs0., _ ., molecular weight x 3, each Cc. of T77 ox1dant would equal of sush salt. 10 M 10,000 Such salts are included in the B.P., but not in the U.S.P. The following table gives the equivalents of 1 Cc. of either oxidant for some of the more important ferrous salts: --Name and formula. Gm. to weigh. Equivalent. Iron (in ferrous salts) Fe--..-00555 Ferrous carbonate (in ferri carb. sacch.)FeC03.. I-15..-011505 sulphate (cryst.) FeS04. 7H20... 139.-027601, anhydrous FeS04... 76. 015085 (dried U.S.P.) 2 FeS04 + 3H20.-895.. 017767 phosphate B P.Fe3(P04)., ....