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Calcium carbonate is a chemical compound with the chemical formula Ca CO 3. It is a common substance found in rocks as the minerals calcite and aragonite , most notably in chalk and limestone , eggshells , gastropod shells , shellfish skeletons and pearls .
Calcium carbonate (CaCO 3) and calcium sulfate (CaSO 4) are particularly abundant minerals. [19] Like strontium and barium, as well as the alkali metals and the divalent lanthanides europium and ytterbium , calcium metal dissolves directly in liquid ammonia to give a dark blue solution.
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.
In the making of calcium oxide, calcium carbonate breaks down upon heating, releasing carbon dioxide: [2] CaCO 3 CaO + CO 2 {\displaystyle {\ce {CaCO3 -> CaO + CO2}}} The reaction of elements with oxygen in air is a key step in corrosion relevant to the commercial use of iron especially.
As the groundwater enters the cave, the excess carbon dioxide is released from the solution of the bicarbonate, causing the much less soluble calcium carbonate to be deposited. In the reverse process, dissolved carbon dioxide (CO 2) in rainwater (H 2 O) reacts with limestone calcium carbonate (CaCO 3) to form soluble calcium bicarbonate (Ca(HCO ...
In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to other atoms are fully ionic. It describes the degree of oxidation (loss of electrons ) of an atom in a chemical compound .
Example: sodium chloride, potassium oxide, or calcium carbonate. When the metal has more than one possible ionic charge or oxidation number the name becomes ambiguous. In these cases the oxidation number (the same as the charge) of the metal ion is represented by a Roman numeral in parentheses immediately following the metal ion name.
Element Negative states Positive states Group Notes −5 −4 −3 −2 −1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 Z; 1 hydrogen: H −1 +1: 1 2 helium: He 0 18