Columbia Encyclopedia

Search results

421 results found

welding

(Encyclopedia)welding, process for joining separate pieces of metal in a continuous metallic bond. Cold-pressure welding is accomplished by the application of high pressure at room temperature; forge welding (forgi...

naphthol

(Encyclopedia)CE5 naphthol năfˈthôl [key], C10H7OH, either of two crystalline monohydric alcohols. The naphthols are position isomers, differing in the location of the hydroxyl group, –OH, on the carbon ske...

plasma

(Encyclopedia)plasma, in physics, fully ionized gas of low density, containing approximately equal numbers of positive and negative ions (see electron and ion). It is electrically conductive and is affected by magn...

Fischer-Tropsch process

(Encyclopedia)Fischer-Tropsch process fĭshˈər-trōpsh [key], method for the synthesis of hydrocarbons and other aliphatic compounds. Synthesis gas, a mixture of hydrogen and carbon monoxide, is reacted in the pr...

chemical reaction

(Encyclopedia)chemical reaction, process by which one or more substances may be transformed into one or more new substances. Energy is released or is absorbed, but no loss in total molecular weight occurs. When, fo...

chlorine

(Encyclopedia)chlorine klōrˈēn, klôrˈ– [key] [Gr.,=green], gaseous chemical element; symbol Cl; at. no. 17; interval in which at. wt. ranges 35.446–35.457; m.p. −100.98℃; b.p. −34.6℃; density 3.2 g...

aryl group

(Encyclopedia)aryl group ârˈĭl [key], in chemistry, group of atoms derived from benzene or from a benzene derivative by removing one hydrogen that is bonded to the benzene ring (see radical). The simplest aryl g...

alcohol

(Encyclopedia)CE5 Alcohols alcohol, any of a class of organic compounds with the general formula R–OH, where R represents an alkyl group made up of carbon and hydrogen in various proportions and –OH represe...

formyl group

(Encyclopedia)formyl group fôrˈmĭl [key], in chemistry, functional group that consists of a carbonyl group joined by a single bond to a hydrogen atom. Aldehydes are compounds that contain a formyl group joined b...

Haber process

(Encyclopedia)Haber process häˈbər [key], commercial process for the synthesis of ammonia, NH3. Pure hydrogen and nitrogen gases are mixed in the appropriate proportion, heated to between 450℃ and 600℃, comp...