Salts That Yield Neutral Solutions

A salt consisting of the anion of a strong acid and the cation of a strong base yields a neutral solution because the ions do not react with water. To see why the ions don t react, let s consider the dissociation of the parent acid and base. When a strong acid such as HNO3 dissolves, complete dissociation takes place  

H2O is a much stronger base than N03, so the reaction proceeds essentially to completion. The same argument can be made for any strong acid the anion of a strong acid is a much weaker base than water. Therefore, a strong acid anion is hydrated, but nothing further happens. 

Now consider the dissociation of a strong base, such as NaOH  

When Na enters water, it becomes hydrated but nothing further happens. The cations of all strong bases behave this way. 

The anions of strong acids are the halide ions, except F , and those of strong oxoacids, such as N03 and C104. The cations of strong bases are those from Group 1 A(l) and Ca, Sr, and Ba from Group 2A(2). Salts containing only these ions, such as NaCl and Ba(N03)2, yield neutral solutions because no reaction takes place between the ions and water. 

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Salts That Yield Neutral Solutions Salts That Yield Acidic Solutions Salts That Yield Basic Solutions Salts of Weakly Acidic Cations and Weakly Basic Anions... 

Acid-Base Properties of Salt Solutions Salts That Yield Neutral Solutions... 

Salts that yield a neutral solution consist of ions that do not react with water. Salts that yield an acidic solution contain an unreactive anion and a cation that releases a proton to water. Salts that yield a basic solution contain an unreactive cation and an anion that accepts a proton from water. If both cation and anion react with water, the ion that reacts to the greater extent (higher K) determines the acidity or basicity of the salt solution. 

Salts that yield a neutral solution consist of ions that do not react with water. 

Consider NaCl, the salt of a strong acid and a strong base. The hydrolysis of this salt /would yield NaOH and HC1. Since both species would completely dissociate lnto -tneir respective ions yielding equivalent amounts of H3O and OK, the overall net effect would be that no hydrolysis takes place. Since [HjOl = [OK], the pH would be 7, a neutral solution. 

A 3 per cent solution of hydrazoic acid (synthesis 26A) is neutralized with an aqueous solution of pure potassium hydroxide. The resulting solution of potassium azide is concentrated on the steam bath to incipient crystallization. The solution is then made slightly acid with hydrazoic acid to replace the hydrogen azide lost by hydrolysis. A volume of ethyl alcohol twice that of the solution is added, and the solution is cooled in an ice bath. Since the solubility in alcohol of the alkali and alkaline earth azides is very slight (see table below), precipitation in the form of a white microcrystalline salt takes place readily. From 90 to 95 per cent recovery of the theoretical quantity of potassium azide can be effected. The precipitated azide is filtered on a Buchner funnel and washed with cold absolute alcohol and then with ether. Any traces of adhering solvent may be removed in a vacuum desiccator. In a typical run, 300 ml. of a solution of hydrazoic acid containing 8.5 g. of HN3 was neutralized with potassium hydroxide, and the isolation of potassium azide effected as indicated above. Yield 14.7 g. (91.5 per cent) KN3. 

While pancreatic and malt amylases are similar in their protein nature and alike in yielding maltose as the chief end product of their action upon starch, there are some respects in which they present marked differences. Thus the optimum activities of these two enzymes are shown at quite different hydrogen ion concentrations that of pancreatic amylase in a practically neutral solution, pH = 6.9 that of malt amylase at the distinctly acid reaction of pH = 4.411 In an extended series of experiments with malt amylase it was found that the optimum hydrogen ion concentration was the same whether this were reached by the addition of a strong acid, a weak acid, or an acid salt.12... 

Bouveault1 claims that the yield of adipic acid is better on electrolyzing the methyl ester-salt in methyl-alcoholic solution. He obtained a yield of 80% by using a mercury cathode and a hollow platinum spiral anode, through which a current of cold water was passed. The acid succinic methyl ester occurs as the principal by-product, also a neutral methyl ester of a tribasic acid which was not investigated. 

Tartrazine occurs as a yellow-orange powder or granules. It is principally the trisodium salt of 4,5-dihydro-5-oxo-l-(4-sulfophenyl) -4-(4- sulfophenyl- azo) - IH-pyrazole- 3- carboxylic acid. When dissolved in water, it yields a solution golden yellow at neutrality and in acid. When dissolved in concentrated sulfuric acid, it yields an orange-yellow solution that turns yellow when diluted with water. It is insoluble in ethanol. 

The structures of the pairs have been determined by ab initio calculations. Surprisingly, while the absorption spectrum of the solvated electron presents a single band located around 2250 nm, the absorption spectra of the pairs are blue-shifted and composed of two bands (Fig. 7)7 Those spectra were interpreted as a perturbation of the solvated electron spectrum with the use of an asymptotic model. This model describes the solvated electron as a single electron trapped in a THF solvent cavity and takes into account the effects of electrostatic interaction and polarization due to the solutes that are modeled by their charge distribution. It was shown that the p-like excited states of the solvated electron can be split in the presence of molecules presenting a dipole. So, the model accounts for the results obtained with dissociated alkali and non-dissociated alkaline earth salts in THF since ionic solutes yield absorption spectra with only one absorption band, and dipolar neutral solutes yield absorption spectra with two bands (Fig. 8). ... 

The same workers demonstrated that catalysis by copper salts affected the rate of (3), but not of (2). Perhaps because the reaction in nearly neutral solution was reported to pursue a remarkable course , no other kinetic work was done on the system for thirty years. A number of determinations of reaction yields were made, however, and these were subsequently rationalized in mechanistic terms. A kinetic study in liquid ammonia demonstrated first-order decomposition of chloramine and confirmed the earlier complex rate behaviour and indicated that it was due to the rapid reaction (3) of hydrazine and chloramine. In this system, the rates of the reaction were apparently independent of acidity (10 -10 M NH4.CI). Liquid ammonia had the advantage of diminishing stray catalytic paths for reaction (3). Yagil and Anbar examined the rates of reaction (2) in aqueous solution in the range pH 10.15 to that of 9.0 M KOH. Between pH 10.15 and 14, the rate expression was... 

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