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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.
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 ...
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 ...
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).
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:
Attempts to prepare compounds such as solid calcium bicarbonate by evaporating its solution to dryness invariably yield instead the solid calcium carbonate: [1] Ca(HCO 3) 2 → CO 2 (g) + H 2 O(l) + CaCO 3 (s). Very few solid bicarbonates other than those of the alkali metals (other than ammonium bicarbonate) are known to exist. [clarification ...
Its usage varies from about 30 to 50 kilograms (65–110 lb) per ton of steel. The quicklime neutralizes the acidic oxides, SiO 2, Al 2 O 3, and Fe 2 O 3, to produce a basic molten slag. [10] 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]
The tetrahydrate crystallizes as a solid solution of Ca 3 (SO 3)2(SO 4). 12H 2 O and Ca 3 (SO 3)2(SO 3). 12H 2 O. The mixed sulfite-sulfate represents an intermediate in the oxidation of the sulfite to the sulfate, as is practiced in the production of gypsum. This solid solution consists of [Ca 3 (SO 3) 2 (H 2 O) 12] 2+ cations and either ...