Synthetic magnesium silicate Synthetic magnesium silicate Synthetic magnesium silicates are white, odorless, finely divided powders formed by the precipitation reaction of water-soluble sodium silicate (water glass) and a water-soluble magnesium salt such as magnesium chloride, magnesium nitrate or magnesium sulfate. The composition of the precipitate depends on the ratio of the components in the reaction medium, the addition of the correcting substances, and the way in which they are precipitated. The molecular formula is typically written as MgO:XSiO, where X denotes the average mole ratio of SiO to MgO. The product is hydrated and the formula is sometimes written MgO:XSiO•HO to show the
Magnesium chloride made from solar evaporation of seawater. Anhydrous magnesium chloride is the principal precursor to magnesium metal, which is produced on a large scale. Hydrated magnesium chloride is the form most readily available. MgCl crystallizes in the cadmium chloride motif, which features octahedral Mg centers. Several hydrates are known with the formula MgCl(HO), and each loses water at higher temperatures: x = 12 (−16.4 °C), 8 (−3.4 °C), 6 (116.7 °C), 4 (181 °C), 2 (about 300 °C). In the hexahydrate, the Mg is also octahedral, but is coordinated to six water ligands. The thermal dehydration of the hydrates MgCl(HO) (x