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Mixed-valence compounds are subdivided into three groups, according to the Robin–Day classification: [3] Class I, where the valences are trapped—localized on a single site—such as Pb 3 O 4 and antimony tetroxide. There are distinct sites with different specific valences in the complex that cannot easily interconvert.
Much of chemistry research is focused on the synthesis and characterization of beneficial products, as well as the detection and removal of undesirable products. Synthetic chemists can be subdivided into research chemists who design new chemicals and pioneer new methods for synthesizing chemicals, as well as process chemists who scale up chemical production and make it safer, more ...
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...
Chemical engineers design, construct, and operate process plants, such as these fractionating columns.. Chemical engineering is an engineering field which deals with the study of the operation and design of chemical plants as well as methods of improving production.
Theoretical chemistry requires quantities from core physics, such as time, volume, temperature, and pressure.But the highly quantitative nature of physical chemistry, in a more specialized way than core physics, uses molar amounts of substance rather than simply counting numbers; this leads to the specialized definitions in this article.
The yield coefficient is defined as the amount of cell mass (kg) or product formed (kg,mol) [Notes 1] related to the consumed substrate (carbon or nitrogen source or oxygen in kg or moles) or to the intracellular ATP production (moles)." [4] [5]: 168
One part per quadrillion (ppq) denotes one part per 1,000,000,000,000,000 (10 15) parts, and a value of 10 −15. This is equivalent to about two and a half minutes out of the age of the Earth (4.5 billion years). Although relatively uncommon in analytical chemistry, measurements at the ppq level are sometimes performed. [3]
The term "fine chemicals" was in use as early as 1908. [1] The emergence of the fine chemical industry as a distinct entity dates to the late 1970s, when the overwhelming success of the histamine H 2 receptor antagonists Tagamet (cimetidine) and Zantac (ranitidine hydrochloride) created a strong demand for advanced organic chemicals used in their manufacture.