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Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca (OH) 2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed with water. Annually, approximately 125 million tons of calcium hydroxide are produced worldwide. [8]
Carbonatation is a slow process that occurs in concrete where lime (CaO, or Ca (OH) 2(aq)) in the cement reacts with carbon dioxide (CO 2) from the air and forms calcium carbonate. The water in the pores of Portland cement concrete is normally alkaline with a pH in the range of 12.5 to 13.5. This highly alkaline environment is one in which the ...
Pure lime is soluble in water containing carbonic acid, a natural, weak acid which is a solution of carbon dioxide in water and acid rain so it will slowly wash away, but this characteristic also produces autogenous or self-healing process where the dissolved lime can flow into cracks in the material and be redeposited, automatically repairing ...
As lime in the form of limewater is added to raw water, the pH is raised and the equilibrium of carbonate species in the water is shifted. Dissolved carbon dioxide (CO 2) is changed into bicarbonate (HCO − 3) and then carbonate (CO 2-3). This action causes calcium carbonate to precipitate due to exceeding the solubility product.
Rain water contains dissolved carbon dioxide taken from the atmosphere. Some of the dissolved carbon dioxide reacts with the water to form carbonic acid, which remains in solution. Minerals containing calcium and magnesium form soluble bicarbonates when exposed to carbonic acid. Water containing these minerals is known as "hard water".
The root of the word calcination refers to its most prominent use, which is to remove carbon from limestone (calcium carbonate) through combustion to yield calcium oxide (quicklime). This calcination reaction is CaCO 3 (s) → CaO (s) + CO 2 (g). Calcium oxide is a crucial ingredient in modern cement, and is also used as a chemical flux in ...
Traditional lime kiln in Sri Lanka. A lime kiln is a kiln used for the calcination of limestone (calcium carbonate) to produce the form of lime called quicklime (calcium oxide). The chemical equation for this reaction is. CaCO 3 + heat → CaO + CO 2. This reaction can take place at anywhere above 840 °C (1,540 °F), but is generally ...
Whitewash cures through a reaction with carbon dioxide in the atmosphere to form calcium carbonate in the form of calcite, a type of reaction generally known as carbonation or by the more specific term, carbonatation. It is usually applied to exteriors, or interiors of rural dairies because of its mildly antibacterial properties. Whitewash can ...