Silicate, dissolved

Keywords FTIR, Raman, alkaline, silicate, dissolved. 

Sampling sites are also referred to as station locations. For water column work, depth profiles are constructed from seawater samples collected at representative depths. Temperature and salinity are measured in situ with sensors. Remote-closing sampling bottles deployed from a hydrowire are used to collect water for later chemical analysis, either on the ship or in a land-based laboratory. The standard chemical measurements made on the water samples include nutrients (nitrate, phosphate, and silicate), dissolved O2, and total dissolved inorganic carbon (TDIC) concentrations. 

Hydrolysis of Sodium Silicate. Dissolve several sodium silicate crystals in hot water and filter the solution if required. Test the action of the solution on phenolphthalein. Explain the change in the colour of the indicator. 

If the analyses of different glasses previously given liad not solved the question, these last two would suffice to demonstrate that all the glasses are silicates in definite proportions, or, at least, mixtures of different definite silicates, dissolved the one by tl e other.. Hence it may be inferred, that by sufficiently prolonging the time of the solidification of a vitreous mass, it would be possible to separate successively compounds more and more fusible, the alkaline base concentrating more and more in the successive residues. And hence, also, may be conceived what takes place in the solidification of lavas, which have so much analogy with the pro. ducts now under consideration, and an explanation may be given of the formation of natural crystals, so diversified as they appear in their mass. 

Silicates. — Dissolve 20 gm. of crystallized sodium carbonate in 30 cc. of hydrochloric acid in a platinum dish, and... 

It must, however, be pointed out that many silicates dissolve completely in the bead so that the absence of a silica skeleton does not conclusively prove that a silicate is not present. 

Some silicate minerals are also formed in a similar manner. The process is very slow, slower than even carbonate formation, because of the very low solubility of silicate minerals. In clay minerals, or in lateritic soils, silicates dissolve very slowly to form an intermediate product, silicic acid (H4Si04), which subsequently will react with other sparsely soluble compounds and form silicate bonding phases. Thus, a dissolution-precipitation process seems to be crucial to forming some silicate minerals. 

The ultimate source of most cations as weU as the silicate dissolved in rivers and the ocean is igneous rock. Granites are light-colored acidic rocks basalts are dark-colored with high concentrations of metal ions. These rocks originate from deep within the Earth, where at one time they were in a molten state. They are made of minerals like feldspar, mica, and quartz. Feldspars are the pink, green, and white minerals visible in granite ... 

When the samples of the glassy substances with P/Si ratios more than 6 are treated with water, almost all the silicate deposits as silicic acid. All phosphate species and trace amounts of silicate dissolve. The compositions of the phosphate species in the solutions were determined by paper chromatography. Solvents A and B reported by Bernhart and Chess (41) were used in this investigation. Solvent A was made by mixing 25 ml. of a 20% trichloroacetic acid solution, 10 ml. of water, and 65 ml. of acetone. Solvent B was made by mixing 25 ml. of a 20% trichloroacetic acid solution, 17 ml. of water, and 58 ml. of acetone. 

Michon, et al (40), studied the silicon metabolism of rabbits after inhalation of a sodium silicate aerosol. They concluded that sodium silicate dissolves in the lungs and is rapidly eliminated in the urine. 

Monomeric crystalline silicates dissolve and are neutralized to liberate monosilicic acid at about pH 2. Kraut (23) prepared monosilicic acid by dissolving sodium meta-silicate hexahydrate in various acidic solutions at low temperature. He reported that monosilicic acid is most stable at around pH 2-3. Weitz, Franck, and Schuchard (20) demonstrated that when Na2Si03-9Hj0 was reacted with acetic acid it liberated Si(OH)4. Also olivine (magnesium orthosilicate, Mg-SiOO dissolved in 1.0 N HCl to give a practically 100% yield of monosilicic acid, the solution containing 0.04% SiO,. Thus monosilicic acid may be liberated from silicates which contain SiO ions separated by cations, such as are present in anhydrous orthosilicates. 

Starting Silicate Dissolved Silicic Acid Type Half-life (sec) K (Sec- ) K (min ) ... 

Inorganic Binders. Inorganic binders are mostly inorganic silicates dissolved in water or solvent that react with moisture in the air after their application to a surface. The type of inorganic binder... 

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