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Magnesium hydroxide is an inorganic compound with the chemical formula Mg(OH) 2. It occurs in nature as the mineral brucite. It is a white solid with low solubility in water (K sp = 5.61 × 10 −12). [5] Magnesium hydroxide is a common component of antacids, such as milk of magnesia.
ions is first treated with lime (calcium oxide) and the precipitated magnesium hydroxide is collected: Mg 2+ (aq) + CaO (s) + H 2 O (l) → Ca 2+ (aq) + Mg(OH) 2 (s) The hydroxide is then converted to magnesium chloride by treatment with hydrochloric acid and heating of the product to eliminate water: Mg(OH) 2 + 2 HCl → MgCl 2 + 2 H 2 O
Calcium hydroxide is moderately soluble in water, as seen for many dihydroxides. Its solubility increases from 0.66 g/L at 100 °C to 1.89 g/L at 0 °C. [8] Its solubility product K sp of 5.02 × 10 −6 at 25 °C, [1] its dissociation in water is large enough that its solutions are basic according to the following dissolution reaction:
This action causes calcium carbonate to precipitate due to exceeding the solubility product. Additionally, magnesium can be precipitated as magnesium hydroxide in a double displacement reaction. [3] In the process both the calcium (and to an extent magnesium) in the raw water as well as the calcium added with the lime are precipitated.
When all the available Na + ions have been replaced with calcium or magnesium ions, the resin must be recharged by eluting the Ca 2+ and Mg 2+ ions using a solution of sodium chloride or sodium hydroxide, depending on the type of resin used. [10] For anionic resins, regeneration typically uses a solution of sodium hydroxide or
Magnesium hydroxide is a strong electrolyte, which can be obtained by the reaction of a soluble magnesium salt and sodium hydroxide. Like magnesium oxide, it will generate a basic carbonate when placed in the air. [3] Magnesium sulfide can be produced by the reaction of magnesium and hydrogen sulfide, or by the reaction of magnesium sulfate and ...
The following chart shows the solubility of various ionic compounds in water at 1 atm pressure and room temperature (approx. 25 °C, 298.15 K). "Soluble" means the ionic compound doesn't precipitate, while "slightly soluble" and "insoluble" mean that a solid will precipitate; "slightly soluble" compounds like calcium sulfate may require heat to precipitate.
For pH control, popular chemicals include calcium carbonate, calcium oxide, magnesium hydroxide, and sodium bicarbonate. The selection of an appropriate neutralization chemical depends on the particular application. There are many uses of neutralization reactions that are acid-alkali reactions. A very common use is antacid tablets.
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