A treatise on chemistry. Vol. III, The chemistry of the hydrocarbons and their derivatives, or, Organic chemistry. Part I / by H.E. Roscoe & C. Schorlemmer.

  • Henry Enfield Roscoe
Date:
1881
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on chemistry. Vol. III, The chemistry of the hydrocarbons and their derivatives, or, Organic chemistry. Part I / by H.E. Roscoe & C. Schorlemmer. Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

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    194X5-22 100 =10-1 of hydrogen, 194x 28-99 , loo = o6*2 01 nitrogen, lO-i X 16-28 ^ = :31-o8 of oxygen. Olio molecule of caffeine, therefore, consists of 96-1 12 10-1 = 8-0 atoms of carbon, = lO'l atoms of hydrogen. 1 56-2 --j^ = 4-0 atoms of nitrogen, 31-58 ~Yq~ ~ atom of oxygen. Its molecular formula is therefore CgHjQN^jOg, corresponding to a molecular weight of 194, or more exactly of 193-78. In the determination of the molecular weight of an organic base we also often know beforehand to which homologous series it belongs. In such a case, the determination of the platinum in the double salt is sufficient to determine the formula. Exam'plc A^o. 9. A compound ammonia, having the general formula Cnllan+sN forms a double salt, 100 parts of which, on ignition, leave a residue of 33-62 of platinum. As the platinum double salt possesses the formula (C„Hon + 3N,C]H)2 + PtCl4, the molecular weight of the base is easily found to be 80, and hence we have the equation: ■ 12 2?i + 3+ 14 = 86 /. n = 4-93. Hence the base possesses the formula CjHjgN, and lias a molecular weight of 80-86. 74 (d) Molecular ForimUce of Non-volaiile and Neutral Bodies. Most carbon compounds, however, neither act as acids nor as bases, and if they are not volatile without decomposition, ami do not enter into combination to form distinct compounds with other elements by means of which the molecular weight can be ascertained, the molecular formulte can be ascertained, in many cases at lenst, by a ravcful examination of their chemical metamorphoses.