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Calcium carbonate is the active ingredient in agricultural lime and is produced when calcium ions in hard water react with carbonate ions to form limescale. It has medical use as a calcium supplement or as an antacid , but excessive consumption can be hazardous and cause hypercalcemia and digestive issues.
Carbonatation induced rebar corrosion. 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.
Calcium deposits, primarily composed of calcium carbonate (CaCO 3), react with weak acids to form calcium salts that are soluble in water. The general reaction can be represented as follows: CaCO 3 + 2H + → Ca 2+ + CO 2 + H 2 O. Here, H + represents the hydrogen ions provided by the acid
When atmospheric carbon dioxide (CO 2), or carbonate ions (HCO − 3, CO 2− 3 dissolved in water) diffuse into concrete from its external surface, they react with calcium hydroxide (portlandite, Ca(OH) 2) and the pH of the concrete pore water progressively decreases from 13.5 – 12.5 to 8.5 (pH of water in equilibrium with calcite).
However, there is an equilibrium between dissolved calcium bicarbonate and dissolved calcium carbonate as represented by the chemical equation Ca 2+ + 2 HCO − 3 ⇌ Ca 2+ + CO 2− 3 + CO 2 + H 2 O. Note that CO 2 is dissolved in the water. Carbon dioxide dissolved in water (aq) tends to equilibrate with carbon dioxide in the gaseous state (g ...
Calcium carbide is used to determine the moisture content of soil. When soil and calcium carbide are mixed in a closed pressure cylinder, the water content in soil reacts with calcium carbide to release acetylene whose pressure can be measured to determine the moisture content. [23] [24] Calcium carbide is sold commercially as a mole repellent ...
Calcium oxide is usually made by the thermal decomposition of materials, such as limestone or seashells, that contain calcium carbonate (CaCO 3; mineral calcite) in a lime kiln. This is accomplished by heating the material to above 825 °C (1,517 °F), [ 6 ] [ 7 ] a process called calcination or lime-burning , to liberate a molecule of carbon ...
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 smelting.