Ammonia alkali metals soluble

Ammonium salts. Ammonium salts can be prepared by the direct neutralisation of acid by ammonia. The salts are similar to alkali metal salts and are composed of discrete ions. Most ammonium salts are soluble in water. Since ammonia is volatile and readily oxidisable the behaviour of ammonium salts to heat is particularly interesting. 

Lead nitrate [10099-74-8] Pb(N02)2, mol wt 331.23, sp gr 4.53, forms cubic or monoclinic colorless crystals. Above 205°C, oxygen and nitrogen dioxide are driven off, and basic lead nitrates are formed. Above 470°C, lead nitrate is decomposed to lead monoxide and Pb O. Lead nitrate is highly soluble in water (56.5 g/100 mL at 20°C 127 g/100 mL at 100°C), soluble in alkalies and ammonia, and fairly soluble in alcohol (8.77 g/100 mL of 43% aqueous ethanol at 22°C). Lead nitrate is readily obtained by dissolving metallic lead, lead monoxide, or lead carbonate in dilute nitric acid. Excess acid prevents the formation of basic nitrates, and the desired lead nitrate can be crystallized by evaporation. 

Lithium-ammonia reduction of l7a-ethyl-19-nortestosterone (68) using Procedure 8a (section V) affords the 4,5a-dihydro compound (69) in 85% yield after a reaction time of 12 minutes after a reaction time of 80 minutes, the yield of (69) is 76%. Lfsing sodium in the same reduction, the yields of compound (69) are 79 and 77 % after reaction times of 8 and 80 minutes respectively. Both the lithium and sodium enolates appear to be reasonably stable in liquid ammonia in the presence of alkali metal. Since the enolate salts are poorly soluble in ammonia, their resistance to protonation by it may be due in part to this factor. 

Adds.—A free acid may be at once identified by its solubility in a holution of sodium carbonate and by being reprecipitated by concentrated hydrochloric acid. If a metal has been dis-coveied in the piehminary examination, a careful examination must be made for an organic acid. As the substance is insoluble ill water the metal will probably not be an alkali metal. Boil the substance with sodium carbonate solution. The sodium salt of the acid passes into solution and the metallic carbonate IS precipitated. Filter boil the filtrate with a slight excess of nitric acid, add excess of ammonia and boil until neutral, tests may then be applied in order to identify one of the common acids and the ni.p. determined but beyond this it is impossible to carry the investigation in a limited time. 

In contrast, these metals dissolve and undergo reaction only very slowly in liquid ammonia. Solutions containing alkali metals in liquid ammonia have been known for more than 140 years, and they have properties that are extraordinary. The extent to which the metals dissolve is itself interesting. The solubilities are shown in Table 10.3. 

Polyatomic anions of tin can be prepared in solution, using alloys of tin with alkali metals which are remarkably soluble in liquid ammonia. The obtained colored solutions contain the cluster anion [Sng]4, 68a106. Upon treatment with a crown ether in ethylenediamine, crystalline compounds [Na(crypt)+]4[Sn9]4 could be prepared where crypt = N(CH2CH20CH2CH20CH2CH2)3N ... 

Fullerenes can be easily chemically reduced by the reaction with electropositive metals [1, 97-99], for example, alkali- and alkaline earth metals. The anions Cjq"" (n = 1-5) can be generated in solution by titrating a suspension of in liquid ammonia with a solution of Rb in liquid ammonia [100], whereupon the resulting anions dissolve. Monitoring of this titration is possible by detecting the characteristic NIR absorption of each anion by UV/Vis/NIR spectroscopy. The solubility of the alkali metal fullerides in the polar solvent NHj demonstrates their salt character. 

Binary Selenides. Most binary selenides are formed by heating selenium in the presence of the element, reduction of selenites or selenates with carbon or hydrogen, and double decomposition of heavy-metal salts in aqueous solution or suspension with a soluble selenide salt, eg, Na2Se or (NH Se [66455-76-3]. Atmospheric oxygen oxidizes the selenides more rapidly than the corresponding sulfides and more slowly than the tellurides. Selenides of the alkali, alkaline-earth metals, and lanthanum elements are water soluble and readily hydrolyzed. Heavy-metal selenides are insoluble in water. Polyselenides form when selenium reacts with alkali metals dissolved in liquid ammonia. Metal (M) hydrogen selenides of the M HSe type are known. Some heavy-metal selenides show important and useful electric, photoelectric, photo-optical, and semiconductor properties. Ferroselenium and nickel selenide are made by sintering a mixture of selenium and metal powder. 

The electro-affinity of lithium is smaller than that of any of the other alkali metals, and it exhibits a greater tendency than the other alkali metals to form complex salts—e.g. the solubility of ammonia in water is raised by the addition of a lithium salt, which presumably unites with the ammonia the solubility curves of the lithium salts in water usually show more breaks than the corresponding salts of the other alkali metals owing to the formation of hydrates. Potassium, rubidium, and caesium seem to have a smaller and smaller tendency to form complex salts as the at. wt. of the element increases otherwise expressed, the electro-affinity, or the ionization tendency of the alkali metals increases as the at. wt. increases. This is illustrated by the heats of ionization. According to W. Ostwald,27 the heat of ionization per gram-atom iB... 

The alkali metals are soluble in liquid ammonia, and certain amines, to give solutions which are blue when dilute. The solutions ate paramagnetic and conduct electricity, the carrier being the solvated electron. In dilute solutions the metal is dissociated into metal ions and ammoniated electrons. The metal ions are solvated in the same way that they would be in a solution of a metal salt in ammonia, and so comparison can be made with, for example, [Na(NH3)4]+I-, the IR and Raman spectra of which indicate a tetrahedral coodination sphere for the metal.39... 

Kraus has shown that many of these compounds of the alkali metals with the less electropositive metals (some of which are soluble in liquid ammonia) possess many of the properties of typical salts. He calls these salts of homoatomic anions. It should be noted that in handbooks or indexes, these compounds are to be found... 

The difference in affinities shown in gas and solution phases suggests that solvent effects are quite important. These ligands have the unusual ability to promote the solubility of alkali sails in organic solvents as a result of the large hydrophobic organic nng. For example, alkali metals do not normally dissolve in ethers as they do in ammonia (see Chapter 10). but they will do so if crown ligands are present ... 

Mercury Arsenites.—Mercurous Orthoarsenite, Hg3As03, may be obtained by treating a solution of mercurous nitrate with one of sodium orthoarsenite6 or with a solution of arsenious oxide in 50 per cent, alcohol 6 in the latter case the mercurous nitrate solution should be acidified with nitric acid and sufficient alcohol added to produce a slight turbidity. The precipitate is pale yellow, but rapidly turns brown on exposure to air. It is slightly soluble in water, being slowly decomposed with separation of mercury. It is also decomposed by hydroxides and carbonates of alkali metals and of barium, and by ammonia. It dissolves in acids, but when these are dilute, basic salts gradually separate. 

Ammonia is a colorless, pungent-smelling gas, consisting of polar, trigonal pyramidal NH3 molecules that have a lone pair of electrons on the N atom. Because of hydrogen bonding (Section 10.2), gaseous NH3 is extremely soluble in water and is easily condensed to liquid NH3, which boils at —33°C. Like water, liquid ammonia is an excellent solvent for ionic compounds. It also dissolves alkali metals, as mentioned in Section 6.7. 

Neutralization of aqueous ammonia with acids yields ammonium salts, which resemble alkali metal salts in their solubility. 

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