calcium oxide
calcium oxide
calcium oxide
| Noun | 1. | calcium oxide - a white crystalline oxide used in the production of calcium hydroxide |
calcium oxide
calcium oxide,
chemical compound, CaO, a colorless, cubic crystalline or white amorphous substance. It is also called lime, quicklime, or caustic lime, but commercial lime often contains impurities, e.g., silica, iron, alumina, and magnesia. It is prepared by heating calcium carbonatecalcium carbonate,CaCO3, white chemical compound that is the most common nonsiliceous mineral. It occurs in two crystal forms: calcite, which is hexagonal, and aragonite, which is rhombohedral.
..... Click the link for more information. (e.g., limestonelimestone,
sedimentary rock wholly or in large part composed of calcium carbonate. It is ordinarily white but may be colored by impurities, iron oxide making it brown, yellow, or red and carbon making it blue, black, or gray. The texture varies from coarse to fine.
..... Click the link for more information. ) in a special lime kiln to about 500°C; to 600°C;, decomposing it into the oxide and carbon dioxide. Calcium oxide is widely used in industry, e.g., in making porcelain and glass; in purifying sugar; in preparing bleaching powderbleaching powder,
white or nearly white powder that is usually a mixture of calcium chloride hypochlorite, CaCl(OCl); calcium hypochlorite, Ca(OCl)2; and calcium chloride, CaCl2.
..... Click the link for more information. , calcium carbide, and calcium cyanamide; in water softeners; and in mortars and cements. In agriculture it is used for treating acidic soils (limingliming
, application to the soil of calcium in various forms, generally as ground limestone, but also as marl, chalk, shells, or hydrated lime. Lime benefits soil by neutralizing acidity, improving texture, and increasing the activity of soil microorganisms.
..... Click the link for more information. ). It is incandescent when heated to high temperatures; the Drummond light, or limelight, provides a brilliant white light by heating a cylinder of lime with the flame of an oxyhydrogen torch. Calcium oxide is a basic anhydride, reacting with water to form calcium hydroxidecalcium hydroxide,
Ca(OH)2, colorless crystal or white powder. It is prepared by reacting calcium oxide (lime) with water, a process called slaking, and is also known as hydrated lime or slaked lime. When heated above 580°C; it dehydrates, forming the oxide.
..... Click the link for more information. ; during the reaction (slaking) much heat is given off and the solid nearly doubles its volume.
Calcium Oxide
(also quicklime), CaO, a compound of calcium and oxygen; colorless crystals with a density of 3.4 g/cm3 and a melting point of 2585°C. The industrial product is a white porous substance. Calcium oxide reacts vigorously with water, liberating a considerable amount of heat and forming calcium hydroxide: CaO + H2O = Ca(OH)2 (slaking process). Calcium oxide is obtained by the calcination of limestone or chalk. It is widely used in construction, the chemical industry, metallurgy, agriculture, and water purification.
calcium oxide
[′kal·se·əm ′äk‚sīd]lime
calcium oxide
calcium oxide
calcium
(Ca) [kal´se-um]Within the body fluids calcium exists in three forms. Protein-bound calcium accounts for about 47 per cent of the calcium in plasma; most of it in this form is bound to albumin. Another 47 per cent of plasma calcium is ionized. About 6 per cent is complexed with phosphate, citrate, and other anions.
Ionized calcium is physiologically active. One of its most important physiological functions is control of the permeability of cell membranes. Parathyroid hormone, which causes transfer of exchangeable calcium from bone into the blood stream, maintains calcium homeostasis by preventing either calcium deficit or excess.
Hypercalcemia: This is when the level of serum calcium rises above normal; neuromuscular activity begins to diminish. Symptoms include lethargy, muscle weakness (which, as the level of calcium increases, can progress to depressed reflexes and hypotonic muscles), constipation, mental confusion, and coma. The heartbeat also slows, which potentiates the effects of digitalis.
Hypocalcemia: This is a serum level of calcium that is below normal; it is manifested by increased neuromuscular irritability. When there is a deficit of ionized calcium, the nerve cells become more permeable, allowing leakage of sodium and potassium from the cells. This produces excitation of the nerve fibers and triggers uncontrollable activity of the skeletal muscles. Hence, as the calcium level continues to drop, the patient begins to experience muscle twitching and cramping, grimacing, and carpopedal spasm, which can quickly progress to tetany, laryngospasm, convulsions, cardiac arrhythmias, and eventually to respiratory and cardiac arrest. Relatively early signs of hypocalcemia are a positive trousseau's sign and a positive chvostek's sign.
Dietary sources of calcium include dairy products (such as milk and cheese), soybeans, fortified orange juice, dark green leafy vegetables (such as mustard greens and broccoli), sardines, clams, and oysters. The allowance" >recommended dietary allowance of calcium for children aged 4 to 8 is 800 mg, and that for women aged 50 to 70 is 1200 mg. (See tables in the Appendices for recommended dietary allowances across the life span.) It is difficult to meet these requirements without including milk or milk products in the daily diet. The most familiar calcium deficiency disease is rickets, in which the bones and teeth soften. However, it is believed that a large number of people suffer from subclinical calcium deficiency because of poor eating habits. Since calcium is essential to the formation and maintenance of strong bones, an adequate intake is important in the prevention of osteoporosis.
lime
(līm),calcium oxide
A whitish, odourless crystal widely used in industry; it is poorly soluble in water, and reacts with water to form calcium hydroxide (CaOH), a base. It has a melting point of 2614ºC and a boiling point of 2850ºC.Toxicity
Mucocutaneous and upper airway irritation, burns with oropharyngeal ulceration, abdominal pain, nausea and vomiting.
See CAO
calcium oxide
- noun
Synonyms for calcium oxide
noun a white crystalline oxide used in the production of calcium hydroxide
Synonyms
- burnt lime
- calcined lime
- calx
- fluxing lime
- quicklime
- unslaked lime
- lime
Related Words
- atomic number 20
- Ca
- calcium
- oxide
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