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 oxychloride It can be prepared by calcination of magnesium hydroxycarbonate ·4 at about 600 °C. (Higher temperatures increase particle size leading to lower reaction rate.) It is believed that, during the reaction, the magnesium oxide is continuously hydrated and dissolved, helped by the slightly acidic character of the magnesium chloride solution. The acidity is attributed to hydrolysis of the magnesium hexahydrate cations: The protons (which are actually hydrated, e.g. as ) make the solution acidic; the pH varies from 6.5 to 4.7 as the concentration of increases from 30% to 70% (weight basis). The protons then react with and dissolve the