WordNet
n. (chemistry) any process determined by the atomic and molecular composition and structure of the substances involved [syn: chemical change, chemical action]
Wikipedia
In a scientific sense, a chemical process is a method or means of somehow changing one or more chemicals or chemical compounds. Such a chemical process can occur by itself or be caused by an outside force, and involves a chemical reaction of some sort. In an " engineering" sense, a chemical process is a method intended to be used in manufacturing or on an industrial scale (see Industrial process) to change the composition of chemical(s) or material(s), usually using technology similar or related to that used in chemical plants or the chemical industry.
Neither of these definitions is exact in the sense that one can always tell definitively what is a chemical process and what is not; they are practical definitions. There is also significant overlap in these two definition variations. Because of the inexactness of the definition, chemists and other scientists use the term "chemical process" only in a general sense or in the engineering sense. However, in the "process (engineering)" sense, the term "chemical process" is used extensively. The rest of the article will cover the engineering type of chemical process.
Although this type of chemical process may sometimes involve only one step, often multiple steps, referred to as unit operations, are involved. In a plant, each of the unit operations commonly occur in individual vessels or sections of the plant called units. Often, one or more chemical reactions are involved, but other ways of changing chemical (or material) composition may be used, such as mixing or separation processes. The process steps may be sequential in time or sequential in space along a stream of flowing or moving material; see Chemical plant. For a given amount of a feed (input) material or product (output) material, an expected amount of material can be determined at key steps in the process from empirical data and material balance calculations. These amounts can be scaled up or down to suit the desired capacity or operation of a particular chemical plant built for such a process. More than one chemical plant may use the same chemical process, each plant perhaps at differently scaled capacities. Chemical processes like distillation and crystallization go back to alchemy in Alexandria, Egypt.
Such chemical processes can be illustrated generally as block flow diagrams or in more detail as process flow diagrams. Block flow diagrams show the units as blocks and the streams flowing between them as connecting lines with arrowheads to show direction of flow.
In addition to chemical plants for producing chemicals, chemical processes with similar technology and equipment are also used in oil refining and other refineries, natural gas processing, polymer and pharmaceutical manufacturing, food processing, and water and wastewater treatment.
Usage examples of "chemical process".
This, as a matter of fact, is perhaps the key chemical process in living tissue, and in the last ten years much has been discovered about its details.
DELKAI Never much better than ordinary, Delkai can be a pleasant and fruity-enough sweet white wine It is the only commercially available wme on Caladan which is produced entirely from native grapes remarkable enough for that reason alone There are a dozen or more different methods of producing the wine, each one a chemical process that is the jealously guarded secret of a single family Depending on the producer the wine may vary from emerald green to straw colored and from syrupy s.
Life had arisen almost immediately after the origin of the Earth, which suggests that life may be an inevitable chemical process on an Earth-like planet.
It was either being outgassed from the planet's interior-unlikely, after twelve billion years-or it was a by-product of some form of non-equilibrium chemical process driven by the light from Voltaire.
The conversion of wood into charcoal may have been the first chemical process developed by human beings for the production of a useful substance.
Linnaeus' method was liable to this objection so far as it required the aid of anatomical dissection, as of the heart, for instance, to ascertain the place of any animal, or of a chemical process for that of a mineral substance.
She had long, glossy black hair that had never been subjected to any chemical process other than regular shampooing.
There's got to be some sequence that will completely inhibit the chemical process, he thought as his fingers tapped the keyboard.
This initiated a chemical process that would rapidly generate heat and, in four minutes, an explosion fiery enough to ignite the remaining contents of the two-gallon can and the trail of fuel leading away from it to the bedroom on the second floor, to the corpse.
The rest it preserved by a curious chemical process, using substances from a small metal pack it had worn and for which it made gestures.
The adhesive, ironically, had been produced using a chemical process given to humans by the Pipe-Rillas.
It took a good deal of the raw ore to make one transmission chip, due to the particular chemical process involved in activating its potential for e-wave transmission, and they wanted all they could get, as cheaply as they could get it.
You begin with an unfertilized egg cell and treat it in such a way as to remove its nucleus, either by delicately cutting it out or by using some chemical process.
Several times both listened, and they agreed that some chemical process was taking place in the bowels of the earth.
Enzymes were those minuscule organic bodies of biological origin whose presence affect the chemical process.