Octadecahydrate

Hydrates. Aluminum sulfate hydrates, Al2(SO H20, where n ranges from 0 to 27 have been reported (3—6). Relative decreasiag vapor pressure studies iadicate the presence of an octadecahydrate, hexadecahydrate, dodecahydrate, dihydrate, and the anhydrous salt, assumiag that basic aluminum sulfates are not formed duriag the dehydration (3). 

Solubility. The aqueous solubiUty of a typical commercial aluminum sulfate, Al2(SO H20, where n = 14-18, is shown compared to the solubihty of the octadecahydrate in Table 1 (2,8). Differences in solubiUties probably result from small amounts of impurities such as iron, and the slight excess of AI2O2 base present in technical grade commercial aluminum sulfate hydrate. 

Ci9H24Nb012P Ca2+ 18 H20 Guanylyl-(3 — 5 )-cytidine, calcium salt, octadecahydrate CAGUCP10 37 430... 

Formula Cr2(S04)s MW 392.16 several hydrates are known these include the pentadecahydrate Cr2(S04)s I5H2O and the octadecahydrate Cr2(S04)3-18H20 Synonym chromic sulfate... 

Reddish-brown hexagonal crystal the pentadecahydrate is a dark green amorphous substance while the octadecahydrate is a violet cubic crystal the densities are 3.10 g/cm (the anhydrous salt), 1.87 g/cm (pentadecahydrate), 1.709/cm (octadecahydrate) the anhydrous sulfate is insoluble in water and acids the hydrate salts are soluble in water the pentadecahydrate is insoluble in alcohol, but the octadecahydrate dissolves in alcohol. 

Crystallization yields the commercial product, pink heptahydrate. Further oxidation of this salt in dilute H2SO4 with ozone or fluorine produces hydrated cobalt(III) sulfate, 002(804)3 I8H2O. This blue octadecahydrate, 002(804)3 I8H2O also is obtained by electrolytic oxidation of cobalt(II) chloride or any cobalt(II) salt solution in 8M sulfuric acid. 

V. Matsuguma et al, KogyoKayaku 33(4), 214-22(1972) CA 78, 6074(1973) (Combustion preventive chemicals for coal mine expls. II. Inorganic compds. Effective compds were aluminum nitrate nonahydrate, aluminum sulfate octadecahydrate and magnesium sulfate heptahydrate)... 

D. PREPARATION OF PURE DODECASODIUM PENTADECATUNGSTODIPHOSPHATE OCTADECAHYDRATE, Na12[ar-P2W15056] 18H20... 

MgS03 (WH4)2S03 nH20 (c). Hartog1 measured the heats of solution in HC1 (aq.) of the hexa- and octadecahydrates. 

Assay Anhydrous Not less than 99.5% of A12(S04)3, calculated on the ignited basis Octadecahydrate Not less than 99.5% and not more than 114.0% of A12(S04)3- 18H20, corresponding to not more than approximately 101.7% of A12(S04)314H20. 

Octadecahydrate. The commercial product is also known as cake alum or patent alum. It is about 99.5% pure. The article of commerce usually contains to 10% lew water than theory. 

Octadecahydrate, needles. Practically insol in water, ethanethiol. 

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