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Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO 2, commonly found in nature as quartz. [5] [6] In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant families of materials, existing as a compound of several minerals and as a
Like other chlorosilanes or silanes, silicon tetrachloride reacts readily with water: . SiCl 4 + 2 H 2 O → SiO 2 + 4 HCl. The reaction can be noticed on exposure of the liquid to air, as SiCl 4 vapour produces fumes as it reacts with moisture to give a cloud-like aerosol of silica and hydrochloric acid. [6]
The first part of the process is to create the colloid precursor which consists of the silica nanoparticles and the solvent. The initial silica nanoparticles are in an amorphous crystalline phase and the solvent is composed of trimethylsilyl chloride (TMCS) and ethyl alcohol. To synthesize hydrophobic nanostructured silica using this method ...
W-silica is an unstable low-density form involving SiO tetrahedra sharing opposite edges instead of corners, forming parallel chains similarly to silicon disulfide (SiS 2) and silicon diselenide (SiSe 2): it quickly returns to forming amorphous silica with heat or traces of water. [14] Condensed polysilicic acid. Silica is rather inert chemically.
The silica cycle plays an important role in long term global climate regulation. The global silica cycle also has large effects on the global carbon cycle through the carbonate-silicate cycle. [43] The process of silicate mineral weathering transfers atmospheric CO 2 to the hydrologic cycle through the chemical reaction displayed above. [4]
[4] [5] [6] Dehydrating the latter yields a hard translucent form of silica with atomic-scale pores, called silica gel, which is widely used as water absorbent and drying agent. Silica dissolves very sparingly in water [citation needed] and is present in seawater at concentrations below 100 parts per million. In such dilute solutions, silica is ...
Sodium silicate is also the technical and common name for a mixture of such compounds, chiefly the metasilicate, also called waterglass, water glass, or liquid glass. The product has a wide variety of uses, including the formulation of cements , coatings, passive fire protection , textile and lumber processing, manufacture of refractory ...
Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer-scale voids and pores. The voids may contain water or some other liquids, or may be filled by gas or vacuum. In the last case, the material is properly called silica ...