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Burning (calcination) of calcium carbonate in a lime kiln above 900 °C (1,650 °F) [4] converts it into the highly caustic and reactive material burnt lime, unslaked lime or quicklime (calcium oxide) and, through subsequent addition of water, into the less caustic (but still strongly alkaline) slaked lime or hydrated lime (calcium hydroxide ...
Carbonatation is a slow process that occurs in concrete where lime (CaO, or Ca(OH) 2 ) 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.
CaO + H 2 O → Ca(OH) 2 Ca(OH) 2 + CO 2 → CaCO 3 + H 2 O. In a laboratory, calcium carbonate can easily be crystallized from calcium chloride (CaCl 2), by placing an aqueous solution of CaCl 2 in a desiccator alongside ammonium carbonate [NH 4] 2 CO 3. [10] In the desiccator, ammonium carbonate is exposed to air and decomposes into ammonia ...
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: Ca(OH) 2 → Ca 2+ + 2 OH −. The solubility is affected by the common-ion effect. Its solubility drastically decreases upon addition of hydroxide or calcium sources.
The less soluble Mg(OH) 2 precipitates because of the common ion effect due to the OH − added by the dissolution of Ca(OH) 2: [7] Mg 2+ + Ca(OH) 2 → Mg(OH) 2 + Ca 2+ For seawater brines, precipitating agents other than Ca(OH) 2 can be utilized, each with their own nuances: Use of Ca(OH) 2 can yield CaSO 4 or CaCO 3, which reduces the final ...
Ground quicklime is used in the production of aerated concrete such as blocks with densities of ca. 0.6–1.0 g/cm 3 (9.8–16.4 g/cu in). [10] Quicklime and hydrated lime can considerably increase the load carrying capacity of clay-containing soils. They do this by reacting with finely divided silica and alumina to produce calcium silicates ...
It consists of calcium cations (Ca 2+) and chloride (Cl −) and hydroxide (− OH) anions. A white solid, it forms by the reaction of hydrogen chloride with calcium hydroxide [3] According to X-ray crystallography, it adopts a layered structure related to brucite (magnesium hydroxide, Mg(OH) 2). [4]
Ca(OH) 2 or CaO · H 2 O: Calcium hydroxide (portlandite) C-S-H: 0.6–2.0 CaO · SiO 2 · 0.9–2.5 H 2 O, with variable composition within this range, and often also incorporating partial substitution of Al for Si: Calcium silicate hydrate: C-A-H: Phase more complex than C-S-H: Calcium aluminate hydrate C-A-S-H: This is even more complex than ...