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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. This is in contrast to ion exchange softening where sodium is exchanged for calcium and magnesium ions.
Calcium hydroxide has many names including hydrated lime, caustic lime, builders' lime, slaked lime, cal, and pickling lime. Calcium hydroxide is used in many applications, including food preparation, where it has been identified as E number E526. Limewater, also called milk of lime, is the common name for a saturated solution of calcium hydroxide.
This is also one of the few chemical reactions known in prehistoric times. [8] CaCO 3 (s) → CaO(s) + CO 2 (g) The quicklime is not stable and, when cooled, will spontaneously react with CO 2 from the air until, after enough time, it will be completely converted back to calcium carbonate unless slaked with water to set as lime plaster or lime ...
An example is when slaked lime (calcium hydroxide) is mixed into a thick slurry with sand and water to form mortar for building purposes. When the masonry has been laid, the slaked lime in the mortar slowly begins to react with carbon dioxide to form calcium carbonate (limestone) according to the reaction: Ca(OH) 2 + CO 2 → CaCO 3 + H 2 O.
The formation of water by the reaction and the moisture from the respiration also act as a solvent for the reaction. Reactions in aqueous phase are generally faster than between a dry gas and a dry solid. Soda lime is commonly used in closed-circuit diving rebreathers and in the anesthesia breathing circuit in anesthesia systems. [8] [9]
Mixtures of calcined lime and finely ground, active aluminosilicate materials were pioneered and developed as inorganic binders in the Ancient world. Architectural remains of the Minoan civilization on Crete have shown evidence of the combined use of slaked lime and additions of finely ground potsherds for waterproof renderings in baths, cisterns and aqueducts. [3]
If the quicklime is slaked with an excess of water then putty or slurry is produced. If just the right quantity of water is used, the result is a dry material (any excess water escaping as steam during heating). This is ground to make hydrated lime powder. Hydrated, non-hydraulic lime powder can be mixed with water to form lime putty.
The limestone blocks were then crushed, afterwards slaked (the process of adding water and constantly turning the lime to create a chemical reaction, whereby the burnt lime, or what is known also as calcium oxide, [7] is changed into calcium hydroxide), and mixed with an aggregate to form an adhesive paste (plaster) used in construction and for ...