Salts that produce acidic solutions

Salts That Produce Neutral Solutions Salts That Produce Basic Solutions Salts That Produce Acidic Solutions Metal Ion Hydrolysis Salts in Which Both the Cation and Anion Hydrolyze... 

Acid-Base Properties of Salts Saits That Produce Neutrai Soiutions Saits That Produce Basic Soiutions Base Strength in Aqueous Solutions Salts That Produce Acidic Solutions... 

C02. Unfortunately, S02 is less soluble (and hence less easily removed by scrubbing) in slightly acid solutions, so that it is extremely difficult in practice to operate a calcium-bascd system in such a manner that SO2 removal is maximized while the quantities of calcium chemicals are minimized in order to approach stoichiometric conditions. As calcium-based slurry systems are usually operated at pH 6-10, disposal of the very large masses of used slurry presents a major problem. A typical power station using a caldnm-based SO2-removal slurry system will produce several hundred tons of spent slurry per day. A further disadvantage of lime or limestone systems is their marked tendency to precipitate insoluble calcium salts inside the scrubber. Unless the scale is removed, the scrubber shortly becomes inoperable. 

Acid-base neutralization reactions are processes in which an acid reacts with a base to yield water plus an ionic compound called a salt. You might recall from Section 2.9 that we defined acids as compounds that produce H+ ions when dissolved in water and bases as compounds that produce OH- ions when dissolved in water. Thus, the driving force behind a neutralization reaction is the production of the stable covalent water molecule by removal of H + and OH- ions from solution. The reaction between hydrochloric acid and aqueous sodium hydroxide to yield water plus aqueous sodium chloride is a typical example ... 

Heteropoly acids and salts that undergo partial hydrolytic degradation in water to produce hydrogen ion can be stabilized in mixed solvents, such as water dioxane, water acetone, water alcohol, etc.ls 114 Thus, when HafPMo O ] is potentio-metrically titrated with base in aqueous solution, it behaves as a six to seven basic acid, however, when similar measurements were carried out in 1 1 water-acetone or water dioxane, the acid was found to be tribasic15,114 ... 

A second type of salt that produces an acidic solution is one that contains a highly charged metal ion. For example, when solid aluminum chloride (AICI3) is dissolved in water, the resulting solution is significantly acidic. Although the Al3+ ion is not itself a Bronsted-Lowry acid, the hydrated ion A1(H20)63+ formed in water is a weak acid ... 

Salts that produce basic solutions Potassium fluoride is the salt of a strong base (KOH) and a weak acid (HF). It dissociates into potassium ions and fluoride ions. 

Salts that produce acidic solutions NH4CI is the salt of a weak base (NH3) and a strong acid (HCl). When dissolved in water, the salt dissociates into ammonium ions and chloride ions. 

Salts that produce neutral solutions Sodium nitrate (NaN03) is the salt of a strong acid (HNO3) and a strong base (NaOH). Little or no salt hydrolysis occurs because neither Na nor NOs" react with water. Therefore, a solution of sodium nitrate is neutral. 

Recall that the conjugate base of a strong acid has virtually no affinity for protons as compared with that of the water molecule. For this reason strong acids completely dissociate in aqueous solution. Thus, when anions such as Cl and NOa are placed in water, they do not combine with and therefore have no effect on the pH. Cations such as and Na" from strong bases have no affinity for and no ability to produce H, so they too have no effect on the pH of an aqueous solution. Salts that consist of the cations of strong bases and the anions of strong acids have no effect on [H ] when dissolved in water. This means that aqueous solutions of salts such as KCl, NaCl, NaNOs, and KNO3 are neutral (have a pH of 7). 

Figure 3.6 shows that salts of strong acids and weak bases are acidic at the equivalence point. Cations of the dissolved salt are hydrolyzed in the water solvent, and the pH of the solution is lowered, indicating that the hydronium ion concentration has increased. In this case, the cations of the salt undergo hydrolysis because they are the positive ions from a weak base. The anions of the salt are the negative ions from a strong acid and do not hydrolyze appreciably. Ammonium chloride, NH Cl, is a salt that produces an acidic solution. 

Acids are substances that produce H+ ion in water solution and bases are substances that produce OH ion. Salts are substances that are composed of ions and that contain a cation other than H+ and an anion other than OH . Salts can be produced by the reaction between H+ ion from an acid and OH ion from a base, a neutralization reaction. As a specific example, consider the reaction of H+ from a solution of sulfuric acid, H2SO4, with OH" from a solution of calcium hydroxide ... 

Dissolve (or suspend) 0-25 g. of the acid in 5 ml. of warm water, add a drop or two of phenolphthalein indicator and neutralise carefully with ca. N sodium hydroxide solution. Then add 2-3 drops of ca. O lN hydrochloric acid to ensure that the solution is almost neutral (pale pink colour). (Under alkaline conditions the reagent tends to decompose to produce the evil-smelling benzyl mercaptan.) If the sodium salt is available, dissolve 0-25 g. in 5 ml. of water, and add 2 drops of ca. 0 -hydrochloric acid. Introduce a solution of 1 g. of S-benzyl-iso-thiuro-nium chloride in 5 ml. of water, and cool in ice until precipitation is Dibasic and tribasic acids will require 0-01 and 0-015 mol respectively. 

In acid solution, the double bond of (203) is hydrogenated to the trans-fused sulfone (204). Presumably, this hydrogenation goes through a cis-fused intermediate that is rapidly epimerized to (204) under the acidic conditions of the reaction. Condensation of the sodium salt of 7,7-ethylenedioxy-3-oxooctanoate (205) with (204) produces (206). Cmde (206) is cyclized, hydroly2ed, and decarboxylated, producing the tricycHc compound (207). Hydrogenation of (207) followed by ketal hydrolysis and cyclization affords (208) in an overall yield of 35% from hydrindandione (203). 

Inorganic Chlorides/Halides — These metallic salts are formed from the reaction of a weak base with the strong acid HCl. Salts such as these dissolve in water to produce a markedly acidic solution. This is exemplified by aluminum chloride, which is corrosive due to the acidity resulting from the hydrolysis that produces aluminum and chlorine ions. Anhydrous AICI3 hydrolyzes violently when contacted by water. 

Bell has calculated Hq values with fair accuracy by assuming that the increase in acidity in strongly acid solutions is due to hydration of hydrogen ions and that the hydration number is 4. The addition of neutral salts to acid solutions produces a marked increase in acidity, and this too is probably a hydration effect in the main. Critchfield and Johnson have made use of this salt effect to titrate very weak bases in concentrated aqueous salt solutions. The addition of DMSO to aqueous solutions of strong bases increases the alkalinity of the solutions. 

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