Amphoteric compounds definition

This is an amphoteric compound because it behaves as both an acid and a base in the Bronsted definition. As an acid, it can donate an H+ and becomes the conjugate base ... 

Amphiphilic compounds as surfactants, 21 Amphoteric surfactant, definition, 386 Analysis speed, importance, 125 Anionic surfactants definition, 387... 

The elements show increasing metallic character down the group (Table 14.6). Carbon has definite nonmetallic properties it forms covalent compounds with nonmetals and ionic compounds with metals. The oxides of carbon and silicon are acidic. Germanium is a typical metalloid in that it exhibits metallic or nonmetallic properties according to the other element present in the compound. Tin and, even more so, lead have definite metallic properties. However, even though tin is classified as a metal, it is not far from the metalloids in the periodic table, and it does have some amphoteric properties. For example, tin reacts with both hot concentrated hydrochloric acid and hot alkali ... 

In very general terms, petroleum is a mixture of (1) hydrocarbon types, (2) nitrogen compounds, (3) oxygen compounds, (4) sulfur compounds, and (5) metallic constituents. Petrolenm prodncts are less well defined in terms of heteroatom compounds and are better defined in terms of the hydrocarbon types present. However, this general definition is not adequate to describe the true composition as it relates to the behavior of the petroleum, and its products, in the environment. For example, the occnrrence of amphoteric species (i.e., compounds having a mixed acid-base natnre) is not always addressed, nor is the phenomenon of molecnlar size or the occnrrence of specific functional types that can play a major role in petrolenm behavior. 

The trivalent state is the characteristic one for all the lanthanides. They form oxides, M203, which resemble the Ca-Ba group oxides and absorb carbon dioxide and water from the air to form carbonates and hydroxides, respectively. The hydroxides, M(OH)3, are definite compounds, having hexagonal structures, and not merely hydrous oxides. The basicities of the hydroxides decrease with increasing atomic number, as would be expected from the decrease in ionic radius. The hydroxides are precipitated from aqueous solutions by ammonia or dilute alkalis as gelatinous precipitates. They are not amphoteric. 

At least two of the recognized mechanisms for the formation of electrical double layers (Hunter, elal. 1981 Russel etal., 1989) are relevant to LB film depositions (1) ionization of carboxylic acid group and amphoteric acid groups on solid surfaces, and (2) differences between the affinities of two phases for ions or ionizable species. The latter mechanism includes the uneven distribution of anions and cations between two immiscible phases, the differential adsorption of ions from an electrolyte solution to a solid surface, and the differential solution of one ion over the other from a crystal lattice. Since the solid-liquid and the film-liquid interfaces are flat, large surfaces and since both have a large, solid-like concentration, the analysis that follows applies to both interfaces. For an interface conformed by a thin film of an amphiphilic compound with the hydrophilic end of the molecule in contact with the water subphase, the equilibrium of charges is based on pH and subphase concentration. The effect of pH is highlighted by the definition of the of the carboxylic acid ... 

Synthesis and antimicrobial activity of 3-formyl analogs of norfloxacin, ciprofloxacin, and pefloxacin have been reported [93]. These studies have shown definitive evidence that the 3-formyl analogs of quinolones function as prodrugs and are oxidized in vivo to carboxylic acids. The higher bioavailability of formyl derivatives may be due to a change in physical and chemical properties by the lack of their amphoteric nature, compared to the parent zwitterionic compounds. 

Sodium isostearoamphoacetate Synonyms Isooctadecanamide, N-[2-[N-(2-hydroxyethyl)-N-carboxymethylamino] ethyl-, sodium salt Isostearoamphoglycinate Classification Amphoteric organic compd. Definition Synthetic compound derived from fatty acids... 

Because of a pronounced amphoteric nature of beryllium, all attempts to obtain beryllium compounds in a sufficiently pure form were unsuccessful for a long time. As a result, many properties of the element and especially its valence and atomic mass were determined incorrectly. Consequently, the place of beryllium in the periodic table was not definitely found for a very long time. Only after it had been firmly established that beryllium is bivalent, that the formula of its oxide is BeO, and atomic mass is 9.01, was it once and for all placed in the upper box of the second group. A great contribution to that was made by the Russian scientist I.V. Avdeev. 

Definition Synthetic compound derived from fatty acids Ionic Nature Amphoteric... 

The height of formalism was reached by Wickert in his definitions of acids and bases in terms of the solvent system. He overlooks such experimental behavior as amphoterism in order to state his definitions wholly in terms of ions. Shatenstein also has pointed out one of the several inconsistencies in Wickert s presentation. Although Wickert defines an acid as an ionic compound the cation of which has an incomplete electronic configuration, he recognizes that ammonium salts are acids in ammonia. Another contradiction of the experimental facts is his listing of antimony trichloride but not aluminum chloride as an acid. 

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