![]() Aqueous solutions of calcium hydroxide are called limewater and are medium-strength bases, which react with acids and can attack some metals such as aluminium ( amphoteric hydroxide dissolving at high pH), while protecting other metals, such as iron and steel, from corrosion by passivation of their surface. This behavior is relevant to cement pastes. At high pH values due to a common-ion effect with the hydroxide anion, its solubility drastically decreases. Calcium hydroxide solutions can cause chemical burns. With a solubility product K sp of 5.02 ×10 −6 at 25 ☌, its dissociation in water is large enough that its solutions are basic according to the following dissolution reaction:Īt ambient temperature, calcium hydroxide ( portlandite) dissolves in water to produce an alkaline solution with a pH of about 12.5. ![]() Limewater, also called milk of lime, is the common name for a saturated solution of calcium hydroxide.Ĭalcium hydroxide is poorly soluble in water, with a retrograde solubility increasing from 0.66 g/L at 100 ☌ to 1.89 g/L at 0 ☌. Calcium hydroxide is used in many applications, including food preparation, where it has been identified as E number E526. It has many names including hydrated lime, caustic lime, builders' lime, slaked lime, cal, and pickling lime. It is a colorless crystal or white powder and is produced when quicklime ( calcium oxide) is mixed with water. Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca( OH) 2.
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