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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:
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.
ca(oh) 2 + co 2 → caco 3 + h 2 o. The carbon dioxide that takes part in this reaction is principally available in the air or dissolved in rainwater [ 9 ] so pure lime mortar will not recarbonate under water or inside a thick masonry wall.
Calcium bicarbonate, also called calcium hydrogencarbonate, has the chemical formula Ca(HCO 3) 2. The term does not refer to a known solid compound; it exists only in aqueous solution containing calcium (Ca 2+), bicarbonate (HCO − 3), and carbonate (CO 2− 3) ions, together with dissolved carbon dioxide (CO 2).
CO 2 + Ca(OH) 2 → CaCO 3 + H 2 O + heat (in the presence of water) Each mole of CO 2 (44 g) reacts with one mole of calcium hydroxide (74 g) and produces one mole of water (18 g). The reaction can be considered as a strong-base-catalysed, water-facilitated reaction.
CaCO 3 (s) + CO 2 (g) + H 2 O(l) → Ca(HCO 3) 2 (aq) This reaction is important in the erosion of carbonate rock, forming caverns, and leads to hard water in many regions. An unusual form of calcium carbonate is the hexahydrate ikaite, CaCO 3 ·6H 2 O. Ikaite is stable only below 8 °C.
Treating the solution of different soluble magnesium salts with alkaline water induces the precipitation of the solid hydroxide Mg(OH) 2: Mg 2+ + 2 OH − → Mg(OH) 2. As Mg 2+ is the second most abundant cation present in seawater after Na +, it can be economically extracted directly from seawater by alkalinisation as described here above.
An aqueous solution containing 120 mg NaHCO 3 (baking soda) per litre of water will contain 1.4285 mmol/l of bicarbonate, since the molar mass of baking soda is 84.007 g/mol. This is equivalent in carbonate hardness to a solution containing 0.71423 mmol/L of (calcium) carbonate, or 71.485 mg/L of calcium carbonate (molar mass 100.09 g/mol).