Dihydrate, definition

An enormous variety of solvates associated with many different kinds of compounds is reported in the literature. In most cases this aspect of the structure deserved little attention as it had no effect on other properties of the compound under investigation. Suitable examples include a dihydrate of a diphosphabieyclo[3.3.1]nonane derivative 29), benzene and chloroform solvates of crown ether complexes with alkyl-ammonium ions 30 54>, and acetonitrile (Fig. 4) and toluene (Fig. 5) solvates of organo-metallic derivatives of cyclotetraphosphazene 31. In most of these structures the solvent entities are rather loosely held in the lattice (as is reflected in relatively high thermal parameters of the corresponding atoms), and are classified as solvent of crystallization or a space filler 31a). However, if the geometric definition set at the outset is used to describe clathrates as crystalline solids in which guest molecules... 

Twinning. Two or more crystals of the same species are sometimes found joined together at a definite mutual orientation, this orientation of the individual crystals being constant in different examples of any one species. Such crystals are said to be twinned. Certain species show this phenomenon frequently, and some species invariably. The most frequent type of twinning is that of calcium sulphate dihydrate (gypsum), which is often found in the form shown in Fig. 41 a. The two crystals appear to be joined at the 100 plane. At the junction there is presumably a sheet of atoms common to the two individuals when the crystal nucleus was formed, two lattices were probably built by deposition on opposite sides of this common sheet of atoms. 

Several hydrates of sodium chloride have been described, but only the dihydrate, NaCl,2H20, seems to have been definitely isolated.5... 

Systems consisting of two different hydrates and vapour have a definite vapour pressure at every temperature. The vapour pressure of the solution, which is a measure of the tendency of the hydrate to give up water, is not completely defined unless the compound (containing less water) which results on the dissociation of the hydrate is also specified. The corresponding pressure temperature diagrams, i.e. the vapour pressure curves, also intersect at quadruple points, namely, those at which three sohd phases are in equihbrium with water vapour, e.g. ice, hexa-hydrate, and tetrahydrate /5, or hexahydrate, tetrahydrate /3 and dihydrate. 

The tetrameric chloride is more readily hydrolyzed to the very stable acid (NH P(O)OH) 2H2O (86, 86, 88). Two octasilver salts were obtained by Stokes (88) the cyclic acid is otherwise tetrabasic. The unit cell sizes of the dihydrate, the dipotassium and dirubidium salts have have been obtained by Corbridge (15). The tetrameric acid is also formed by decomposition of the pentameric acid (90). There is little definite information on the higher acids 90, 91). 

Definition Mixt. of mono- and dihydric phenols contg. cardanol and cardol with long alkyl unsat. chain substitutes Empirical C21H34O Formula CeH, OH C15H29... 

CAS 7631-95-0 EINECS/ELINCS 231-551-7 Synonyms Molybdic acid, sodium salt Sodium molybdate (VI) Definition Avail, commercially as anhyd. or dihydrate Empirical MoNajO,... 

Definition Calcium salt of tartaric acid avail, as the dihydrate and tetrahydrate Empirical C4H4CaOe... 

CAS 8007-24-7 EINECS/ELINCS 232-355-4 Synonyms Cashew nutshell liq. Cashew shell liq. CNSL 3-(n-Penta-8 -decenyl) phenol Definition Mixt. of mono- and dihydric phenols contg. cardanol and cardol with long alkyl unsat. chain substitutes Empirical C21H34O Formula C6H4 OH C15H29 Properties Brn. liq. dens. 0.943-0.968 vise. 600 cps b.p. 223-227 C (1.3 kPa)... 

Definition A polyol derived exclusively from sugar mixt. of two components 6-0-D-glucopyranosyl-D-sorbitol and 1-0-D-glycopyranosyl-D-mannitol-dihydrate... 

Definition Avail, as the dihydrate Empirical C2H2NI04 Formula (HCOO)2Ni... 

Classification Org. dicarboxylic acid Definition Avail, commercially as the dihydrate Empirical C2H2O4... 

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