Ammonia amphoterism

It is readily dehydrated on warming, to give the black oxide CuO. It dissolves in excess of concentrated alkali to form blue hydroxo-cuprate(II) ions, of variable composition it is therefore slightly amphoteric. If aqueous ammonia is used to precipitate the hydroxide, the latter dissolves in excess ammonia to give the deep blue ammino complexes, for example [Cu(NH3)4(H20)2] ... 

In its chemistry, cadmium exhibits exclusively the oxidation state + 2 in both ionic and covalent compounds. The hydroxide is soluble in acids to give cadmium(II) salts, and slightly soluble in concentrated alkali where hydroxocadmiates are probably formed it is therefore slightly amphoteric. It is also soluble in ammonia to give ammines, for example Of the halides, cadmium-... 

Chloroacetic acid can be esterified and aminated to provide useful chemical intermediates. Amphoteric agents suitable as shampoos have been synthesized by reaction of sodium chloroacetate with fatty amines (4,5). Reactions with amines (6) such as ammonia, methylamine, and trimethylamine yield glycine [66-40-6J, sarcosine [107-97-17, and carhoxymethyltrimethylammonium chloride, respectively. Reaction with aniline forms /V-phenylglycine [103-01 -5] a starting point for the synthesis of indigo (7). 

Cadmium is rapidly oxidized by hot dilute nitric acid with the simultaneous generation of various oxides of nitrogen. Unlike the ziac ion, the cadmium ion is not markedly amphoteric, and therefore cadmium hydroxide [21041-95-2] Cd(OH)2, is virtually iasoluble ia alkaline media. However, the cadmium ion forms stable complexes with ammonia as well as with cyanide and haUde ions. The metal is not attacked by aqueous solutions of alkaU hydroxide. 

Copper hydroxide is almost iasoluble ia water (3 p.g/L) but readily dissolves ia mineral acids and ammonia forming salt solutions or copper ammine complexes. The hydroxide is somewhat amphoteric dissolving ia excess sodium hydroxide solutioa to form ttihydroxycuprate [37830-77-6] [Cu(011)3] and tetrahydroxycuprate [17949-75-6] [Cu(OH) ]. ... 

Ammonia a base, 184 boiling point, 64 complexes, 392, 395, 408 complex with Ag+, 154 Haber process for, 150 and hydrogen chloride, 24 model of, 21 molar volume. 60, 64 production, 150 P V behavior of, 19, 51, 60 solubility, 20 Ampere, 241 Amphoteric, 371 complexes, 396 Analogy... 

Aqueous ammonia is a weak base, so relatively few hydroxide ions form. The position of equilibrium lies to the left. In the forward reaction, the water molecule gives up a proton and acts as an acid. A substance that can act as a proton donor (an acid) in one reaction and a proton acceptor (a base) in another reaction is said to be amphoteric. (Water acts as an acid in tbe presence of a stronger base, and as a base in tbe presence of a stronger acid. 

The amphoteric indium oxide can be considered as more basic than acidic when comparing the adsorption heats and irreversible adsorbed amounts, which are clearly higher for SO2 adsorption than for ammonia adsorption [40,47]. The heats of NH3 adsorption decreased continuously with coverage, while the SO2 adsorption heat remained constant over a wide range of coverage. 

Chemical Properties. Zinc oxide is amphoteric it reacts with organic and inorganic acids, and also dissolves in alkalis and ammonia solution to form zincates. It combines readily with acidic gases (e.g., C02, S02, and H2S). It reacts at high temperatures with other oxides to form compounds such as zinc ferrites. 

If a substance can behave both as a Bronsted-Lowry acid and as a Bronsted-Lowry base then it is called amphoteric. Water has this ability. As well as reacting with acids (above) it can also react with Bronsted-Lowry bases such as ammonia in the following way to form the base OH ... 

IV. Comparison of the Rate of Hydrogen Exchange in Ammonia and in Amphoteric Solvents... 

There is a separate scale for bases, but it seems silly to have two different scales, the basic pKB and the familiar pKa, when one will do and so we will stick to pK However, to avoid any misunderstandings that can arise from amphoteric compounds like ammonia, whose pKa is around 33. we will either say ... 

It is readily apparent that Zn(OH)2 is amphoteric in aqueous solution and that Zn(NH2)2 behaves in an analogous way in liquid ammonia. Other examples of amphoterism in nonaqueous solvents are A12(S03)3 in liquid S02 and Zn(C2H302)2 in glacial acetic acid. 

These equations are analogous to those shown earlier for amphoteric behavior of Zn2+ and Al3+ in water, liquid ammonia, and liquid hydrogen fluoride. 

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