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General |
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| Name | Calcium oxide |
| Chemical formula | Ca O |
| Appearance | White solid |
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Physical |
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| Formula weight | 56.1 amu |
| Melting point | 3200 K (2927 °C) |
| Boiling point | 3773 K (3500 °C) |
| Density | 3.3 ×103 kg/ m3 |
| Crystal structure | NaCl |
| Solubility | hydrolysed |
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Thermochemistry |
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| ΔfH0gasThe standard enthalpy of formation of a compound is the change of enthalpy that accompanies the formation of 1 mole of that substance from its component elements, at their standard states (the most stable form of the element or compound at 25 degrees Cels | 43.93 kJThe joule (symbol J also called newton metre or coulomb volt is the SI unit of energy and work. The unit is pronounced to rhyme with "tool", and is named in honour of the physicist James Prescott Joule (1818-1889). 1 joule 1 N · 1 m 1 newton · 1 metre 1 k/ molThe mole (symbol: mol) is one of the seven SI base units and is commonly used in chemistry. It measures the amount of substance of a system and is defined as the amount of substance that contains as many elementary entities as there are atoms in exactly 0 |
| ΔfH0liquid | -557.33 kJ/mol |
| ΔfH0solid | -635.09 kJ/mol |
| S0gas, 1 barIn chemistry, the standard molar entropy is the entropy content of one mole of substance, under conditions of standard temperature and pressure. By comparing the entropies of products and reactants in a chemical reaction, we can determine whether the reac | 219.71 J/mol·K |
| S0liquid, 1 bar | 62.31 J/mol·K |
| S0solid | 38.19 J/mol·K |
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Safety | |
| Ingestion | Dangerous—causes GI irritation, larger doses could be fatal. |
| Inhalation | Dangerous - irritation; chemical bronchitis or even death for larger exposures. |
| Skin | Irritation and possible burns. |
| Eyes | May cause permanent damage. |
| More info | Hazardous Chemical Database |
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SIThe International System of Units (symbol: SI (for the French phrase Systeme International d'Unites , is the most widely used system of units. It is used for everyday commerce in virtually every country of the world except the United States, and it is uni units were used where possible. Unless otherwise stated, standard conditions were used. | |
Calcium oxide (CaO), commonly known as lime or quicklime, is a widely used chemical compound. It is a white, caustic and alkaline crystalline solid. As a commercial product lime often also contains magnesium oxide, silicon oxide and smaller amounts of aluminium oxide and iron oxide.
Calcium oxide is usually made by the thermal decomposition of materials, such as limestone, that contain calcium carbonate (CaCO3). This is accomplished by heating the material to around 500° C and so removing the carbon dioxide in a reversible reaction. It is one of the first chemical reactions discovered by man and was known in prehistory: see limekiln.As hydrated or slaked lime, Ca(OH)2, it was used in mortar and plaster to increase the rate of hardening. Hydrated lime is very simple to make as lime is a basic anhydride and reacts vigorously with water. Lime was also used in glass production and its ability to work with silicates is also used in modern metal production ( steel, magnesium, aluminium and other non-ferrous metals) industries to remove impurities as slag.
It is also used in water and sewage treatment to reduce acidity, to soften, as a flocculant and to remove phosphates and other impurities; in paper making to dissolve lignin, as a coagulant and in bleaching; in agriculture to improve acid soils; and in pollution control - in gas scrubbers to de sulfurize waste gases and to treat many liquid effluents. It is a refactory and a dehydrating agent and is used to purify citric acid, glucose, dyes and as a CO2 absorber. It is also used in pottery, concrete, paints and the food industry.