Metasilicic acid

HPO3 metaphosphoric acid H2S103 metasilicic acid... 

Metasilicic acid, H2Si03, and orthosilicic acid, H4Si04, are weak acids. However, when a solution of sodium orthosilicate is acidified, instead of H4Si04, a gelatinous precipitate of silica is produced ... 

Polymeric chain, band- and sheet silicate structures have been discussed previously (page 742), and it should not be surprising to learn that cyclic silicate anions, such as [Si3Oy]ft and [Si601B]l2 (Fig. 16.28) are known. These anions are sometimes referred to as metasilicates in line with the older system of nomenclature, which assigned vrtlto to the most fully hydrated species [as in orthosilicic acid." Si(QH)J and metu to the acid (and anion) from which one mole of water has been removed [either in fact or formally for example, "metasilicic acid," OSi(OH)2]. 

Dilute hydrochloric acid Silicates, Si032- Gelatinous precipitate of metasilicic acid insoluble in concentrated acids soluble in water and dilute acids... 

Salts of silicic acids. The silicates may be looked upon as salts of a considerable variety of silicic acids, some of which are far more complex than any acids discussed thus far. The two simplest acids of silicon are orthosilicic and metasilicic acids. The relationship between these two acids and their anhydride may be shown as follows ... 

Water glass. A familiar and useful silicate is that known as water glass. Although the commercial product consists of a rather complex mixture of silicates, water glass is commonly represented by the formula for the normal sodium salt of metasilicic acid, Na2Si03. This material is produced by heating sand with sodium hydroxide under pressure... 

The addition of an acid to a sodium silicate solution causes a separation of silicic acid which appears as a jelly-like substance. Orthosilicic acid has the composition HtSiCh, metasilicic acid, H2Si03 the acid corresponding to the sodium salt of the above formula, H2Si409. Suspended in water these different silicic acids are more or less easily interchangeable one into another, but, if silicic acid is heated, it loses all its water and becomes the anhydride. The anhydride practically will not take on water again to form acids. 

Dilute hydrochloric acid Add dilute hydrochloric acid to the solution of the silicate a gelatinous precipitate of metasilicic acid is obtained, particularly on boiling. The precipitate is insoluble in concentrated acids. The freshly precipitated substance is appreciably soluble in water and in dilute acids. It is converted by repeated evaporation with concentrated hydrochloric acid on the water bath into a white insoluble powder (silica, Si02). 

SYNS KIESELSAEURE (GERMAN) METASILICIC ACID PRECIPITATED SILICA SIUCA GEL SIUCIC ACID... 

H,Si03) metasilicic acid poly(dihydrogen trioxosilicate) polytrioxosilicic acid... 

H2Si03) = TSi(0H)20T metasilicic acid cafena-poly[dihydroxidosilicon-p-oxido]... 

Infinite Chain Anions. These are of two main types, the pyroxenes, which contain single-strand chains of composition (SiO ) (Fig. 11-3) and the amphiboles which contain double-strand, cross-linked chains or bands of composition (Si Of ),. Note that the general formula of the anion in a pyroxene is the same as in a silicate with a cyclic anion. Silicates with this general stoichiometry are often, especially in older literature, called metasilicates. There is actually neither metasilicic acid nor any discrete meta-silicate anion. With the exception of the - few— -metasilicates with-cychc -anions, such compounds contain infinite chain anions. 

Glasses are three-dimensional polymers whereas fibrous or ladder silica is linear and unidimensional. Fibrous silica readily reacts with water or alcohol, forming metasilicic acid or a polymeric ester of metasilic acid ... 

The yield depends solely on the degree to which moisture is excluded and on the water content of the alcohol. If, for example, 96% alcohol is used instead of absolute alcohol, the principal product will be esters of disilicic acid and polymeric metasilicic acid. Esters of other alcohols can be obtained in the same manner in the preparation of the methyl ester, however, special care must be taken to exclude moisture, and perfectly dry methanol must be used. 

H2Si03 (Si02 + H2O) is metasilicic acid. See also meta- para-. 

The most important ion in rocks is the silicate SiO " (in analogy to sulfate S04 ) from the weak orthosilicic acid H4Si04 = Si (OH)4. It is in equilibrium with silicon dioxide (Si02) by condensation (and liberation of H2O) via metasilicic acid (H2Si03) ... 

CAS 63231-67-4 977052-02-0 EINECS/ELINCS 231-545-4 Synonyms Metasilicic acid Silica aerogel Definition A regenerative adsorbent consisting of coherenL continuous three-dimensional network of spherical particles of colloidal silica Empirical OiSi Formula SiOj... 

CAS 7699-41-4 EINECS/ELINCS 231-716-3 Synonyms Metasilicic acid Precipitated silica Silica gel Silica, gel and amorphous-precipitated Empirical HjOjSi... 

Metasap Zinc Stearate. See Zinc stearate Metasilicic acid. See Silicic acid Silica gel Metasol 350. See Dodecylguanidine hydrochloride Metasol 550. See Glutaral Metasol 600 HF. See Dodecylguanidine hydrochloride... 

Free metasilicic acid is contained in waterglasses with M > 2 and thus formation of linear polymers becomes possible ... 

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