Aromatic hydrocarbon

Aromatic hydrocarbon A hydrocarbon with  a chemistry similar to that of benzene. Aromatic hydrocarbons are either benzenoid or nonbenzenoid. Benzenoid aromatic hydrocarbons contain one or more benzene rings and are by far the more common and the more important commercially. Nonbenzenoid aromatic hydrocarbons have carbon rings that are either smaller …

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Aqua regia

Aqua regia A mixture of one part by volume of concentrated nitric acid and three parts of concentrated hydrochloric acid. Aqua regia was so named by the alchemists because of its ability to dissolve platinum and gold. Either acid alone will not dissolve these noble metals.

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Antimony

Antimony A chemical element, symbol Sb, atomic number 51. Antimony is not a naturally abundant element; it is occasionally found native, often in isomorphous mixture with arsenic, as allemonite. The symbol Sb is derived from the Latin name stibium. The element is dimorphic, existing as a yellow, metastable form composed …

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Ammonium Salt

Ammonium salt A product of a reaction between ammonia, NH3, and various acids. The general reaction for formation is NH3 + HX –+ NH2X. Examples of ammo­nium salts are ammonium chloride, NH4Cl, ammonium nitrate, NH4NO3,  These compounds are ad­dition products of ammonia and the acid. For this reason, their formulas …

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Ammonia

Ammonia The most familiar compound composed ‘of the elements nitrogen and hydrogen, NH3. It is formed as a result of the decomposition of most nitrogenous organic material, and its presence is indicated by its pungent and irritating odor. Ammonia has a wide range of industrial and agricultural applications. Examples of …

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Aspirin

Aspirin The acetyl ester of salicylic acid, also known as 2-(acetyloxy)-benzoic acid and acetylsalicylic acid (see structure below). Aspirin is prepared by the acetylation of salicylic acid with acetic anhydride. Aspirin is effective as an analgesic, antipyretic, and anti-inflammatory drug. It pre­vents the aggregation of platelets, and there is some …

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Argon

Argon A chemical element, Ar, atomic number 18, and atomic weight 39.948. Argon is the third member of group 18 in the periodic table. The gaseous elements in this group are called the noble, inert, or rare gases, although argon is not actually rare. The Earth’s atmosphere is the only …

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Ammine

Ammine One of a group of complex compounds formed by the coordination of ammonia molecules with metal ions and, in a few instances, such as calcium, strontium, and barium, with metal atoms. Although ammines are formally analogous to many salt hydrates, the general characteristics of the group of ammines differ …

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Amino acids

Organic compounds possessing one or more basic amino groups and one or more acidic carboxyl groups. Of the more than 80 amino acids which have been found in living organisms, about 20 serve as the building blocks for the proteins. All the amino acids of proteins, and most of the …

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Ascorbic Acid

Ascorbic acid A white, crystalline compound, also known as vitamin C. It is highly soluble in water, which is a stronger reducing agent than the hexose sugars, which it resembles chemically. Vitamin C deficiency in humans has been known for centuries as scurvy.The compound has the structural formula shown below. …

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