Neutralization Reactions and Salts

The properties of acidic solutions are quite different from those of basic solutions. Acids have a sour taste, whereas bases have a bitter taste. Acids change the colors of certain dyes in a way that differs from the way bases affect the same dyes. This is the principle behind the indicator known as litmus paper ( FIGURE 4.8). In addition, acidic and basic solutions differ in chemical properties in several other important ways that we explore in this chapter and in later chapters. 

When a solution of an acid and a solution of a base are mixed, a neutralization reaction occurs. The products of the reaction have none of the characteristic properties of either the acidic solution or the basic solution. For example, when hydrochloric acid is mixed with a solution of sodium hydroxide, the reaction is 

A FIGURE 4.8 Litmus paper. Litmus paper is coated with dyes that change color 

Water and table salt, NaQ, are the products of the reaction. By analogy to this reaction, the term salt has come to mean any ionic compound whose cation comes from a base (for example, Na from NaOH) and whose anion comes from an acid (for example, CP from HCl). In general, a neutralization reaction between an acid and a metal hydroxide produces water and a salt. 

Because HCl, NaOH, and NaCl are all water-soluble strong electrolytes, the complete ionic equation associated with Equation 4.12 is 

Equation 4.14 summarizes the main feature of the neutrahzation reaction between any strong acid and any strong base H aq) and OH (oq) ions combine to form H20(Z). 

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If you remember from Chapter 11, we said that if an acid and base are mixed together, a neutralization reaction occurs that produces water and a salt. In this section, we are going to look a bit more closely at the salts that form in neutralization reactions (and salts in general). If you remember, a neutralization reaction takes the form ... 

The melting point of the pure nicotinic acid salt is 180°C and the yield is 75% to 80% related to the used theophylline. The substance has a nearly neutral reaction and is very readily soluble in water. 

The reaction between an acid and a base is called a neutralization reaction, and the ionic compound produced in the reaction is called a salt. The general form of a neutralization reaction of a strong acid and a metal hydroxide that provides the hydroxide ion, a strong base, in water is... 

Neutral solutions also contain a dissolved salt, derived from the neutralization of the acid and the base (a salt is an ionic compound formed in a neutralization reaction and is composed of the cation of an alkali and the anion of an acid). When a solution of carbonic acid (formed when atmospheric carbon dioxide dissolves in water), for example, reacts with an alkaline solution of lime, the two solutions neutralize each other and form a salt, calcium carbonate ... 

Precisely similar considerations appear to apply to iodine penta-fluoride, though this has been studied in less detail. Thus from SbFg and IFg the acid IF4SbFg may be isolated, while with KF the base KIFg is formed. These two substances undergo a neutralization reaction and form the salt KSbFg. 

The most common ionic liquids include alkylammonium, alkylphosphonium, A/-alkylpyridinium, and A/A/ -dialkylimidazolium cations. Two general methods for their preparation are acid-base neutralization reactions and metathesis of halide salts with a metal or ammonium salts. Alkylammonium, pyridinium, and imidazo-lium halides can be prepared by the reaction of the appropriate alkyl halide and amine. Preparation of l-ethyl-3-methylimidazolium chloride [emimjCl requires a sealed tube since it has a low boiling point. On the other hand, synthesis of [bmim] Cl can be achieved under conventional reflux conditions [33, 34]. 

Sodium hydroxide is a base reacting with sulfuric acid. This is a neutralization reaction, and one product is water. The other is the salt formed as sodium replaces hydrogen in the acid, Na2S04faq). The completed equation is ... 

This is a simple calculation because it involves a complete neutralization reaction and the salt (NaCl) does not undergo hydrolysis. At the equivalence point, [H+] = [OH ] and the pH of the solution is 7.00. 

Schulze and Trier discovered betonicine, C7H13O3N, in Betonica officinalis L. and in Stachys sylvatica L. (43, 58). This alkaloid has a sweet taste, a neutral reaction and is readily soluble in water but difficultly so in cold alcohol. Crystallization from this latter solvent yields short, four-sided, truncated pyramids containing a molecule of water of crystallization, C7H13O3N H2O. These crystals, after drying, melted at 252° (dec) (59) and at temperatures in excess of this produced a vapor which shows an intense pyrrole reaction. It is optically active, [a ]D 36.6° (water), and forms salts readily. The hydrochloride separates from ethanol as colorless prismatic needles, m.p. 224° (dec) [a]J —24.8° (water), the chloroaurate, clusters of small yellow tablets, melts at 230-232° (dec) and the chloroplatinate, (B HCLjPtCU, melts at 225-226° (dec). 

It is readily soluble in water, from which it crystallizes with one molecule of water. The anhydrous imide melts at 126° and boils at 287°-288°. Although succinimide has a neutral reaction and does not decompose carbonates, it forms salts in which one hydrogen is replaced by a metallic atom. Potassium hydroxide and succinimide react in alcoholic solution to form a salt to... 

It shows IR spectrum band at 4.57 i. It gives rise to several well defined derivatives, such as (i) Red monohydrate C H N Og (ii) Potassium salt obtained from (i), KC HgN Og, which being slightly soluble in water having almost neutral reaction and (Hi) Alcoholates. 

Thus, the most favorable quantity of acid is o 2 per cent HQ. Sulphuric acid, in equimolal quantities, gives the same effect. Acetic acid, in equimolal quantities, is still more favorable than HCl, but phosphoric acid is less favorable than HQ. The neutral reaction, and especially the alkaline reaction, exerts a retarding effect. The influence which salts produce on the activity of endotryptase is as follows... 

Within clinical dentistry, there are several types of cement available, including the zinc phosphate and the zinc polycarboxylate. They share with glass-ionomers the feature of being acid-base cements and setting as the result of a neutralization reaction, and consequently they are hydrophilic by nature [7]. These cements differ from each other in that they have different acid and base components, but they resemble each other in that the acid is always an aqueous solution and the base is a water-insoluble soUd metal oxide powder. The setting reaction, which begins immediately when the components are mixed, involves acid attack on the solid powdered base, and leads to the release of metal ions into the aqueous phase. In this phase, the metal ions interact with the acid (or its anion) to form metal salts, and these are rigid and insoluble. As these salts form, so the overall cement hardens and becomes insoluble in saliva and other aqueous media [7]. 

Aqueous solutions of caustic soda aie highly alkaline. Hence caustic soda is ptimatily used in neutralization reactions to form sodium salts (79). Sodium hydroxide reacts with amphotoric metals (Al, Zn, Sn) and their oxides to form complex anions such as AlO, ZnO. SnO ", and (or H2O with oxides). Reaction of AI2O2 with NaOH is the primary step during the extraction of alumina from bauxite (see Aluminum compounds) ... 

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