Reactions of anions with water

Changing the pH of the water affects the equilibrium between the various protonated forms. In solutions with a high pH, the PO ion (5a = 0.25vu) is stabilized because the excess OH ions (. a = (l +0.17)/3 = 0.39 vu) are a better 

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Hydrolysis is the general term of the chemical reaction of anions with water. Salts of weak acids and bases hydrolyze in aqueous solutions. 

Although the equation Kg Kb = K permits quantitative predictions to be made concerning the extent of reaction of anions with water, we will concern ourselves only with the following qualitative conclusions ... 

For many years it was thought that fluorine did not form any 0x0-acids or oxo-acid anions. Recent work, however, indicates the existence of fluoric(I) acid (hypofluorous acid), HFO, formed by the reaction of fluorine with water at 273 K. The acid forms colourless crystals, m.p. 156 K, is very unstable and has, as expected, very strong oxidising properties. 

Hydroxides MOH are important compounds for all the alkali metals. They can easily formed by reaction of oxides with water (or atmosphere moisture). They are soluble in water and give strong base. Compounds of oxoacids are commonly encountered, such as carbonate, nitrate, sulphate, etc. as these anions are fairly large, lithium compounds tend to be the most soluble in the series. Many of these compounds crystallise in a variety of hydrated forms (e.g. Na2C03. H2 O with n = 1, 7 or 10). 

At ordinary temperature and pressure quartz is the stable modification of silica. Quartz does not noticeably react with water but is readily attacked by HF. A less dense metastable modification of Si02 called silica W [after Weiss and Weiss (35)] reacts readily with water and forms a yellow silver silicate in contact with an aqueous solution of AgNOs. Another newly discovered but dense modification of Si02, called silica C [after Coes (6)], which is also metastable under ordinary conditions, is so unreactive that even the smallest crystals are not noticeably attacked by HF. The rates of the reactions of Si02 are determined by the polarizability of the O-2 ions. The O-2 ions are most polarizable in the low density form (silica W) and least polarizable in the high density form (silica C). The reactions of silica with water are initiated by the penetration of protons into the electron clouds of the O-2 ions and the rate of proton penetration increases with increasing polarizability of the anions. The phenomena described are strictly rate phenomena, because neither quartz nor the two metastable forms of silica are in equilibrium with HF. 

By propoxylation of this mixture of sucrose - water, in anionic catalysis (KOH or NaOFI), propylene oxide (or EO) react not only with the hydroxyl groups of sucrose but react with water too, which is not an inert compound in this reaction (see Chapter 4). The reaction of PO with water causes diols (propyleglycol, dipropyleneglycol, etc.) to be formed, which decrease markedly the functionality of the resulting sucrose polyol. In order to minimise as much as possible, the diol formation, the propoxylation reaction of the sucrose - water mixture is divided into two steps ... 

SECTION 16.9 The acid-base properties of salts can be ascribed to the behavior of their respective cations and anions. The reaction of ions with water, with a resultant change in pH, is called hydrolysis. The cations of... 

ACID-BASE PROPERTIES OF SALTS (SECTION 16.9) The acid-base properties of salts can be ascribed to the behavior of their respective cations and anions. The reaction of ions with water, with a resultant change in pH, is called hydrolysis. The cations of the alkali metals and the alkaline earth metals as well as the anions of strong acids, such as Cl , Br , F, and NO3 , do not undergo hydrolysis. They are always spectator ions in acid-base chemistry. A cation that is the conjugate acid of a weak base produces H upon hydrolysis. 

Show a mechanism (a sequence of molecular-level events) of the reaction of BaO with water to produce aqueous barium cations and hydroxide anions. 

One of the major problems of lithium polymer electrolyte systems is the development of high interfacial resistance at the lithium/polymer electrolyte interphase. This resistance grows with time and could be as high as 10 kO cm. This resistance layer is due to the reactions of lithium with water, other impurities, and the salt anions. Similar to nonaqueous electrolytes, the solid electrolyte interphase (SET) also exists in the lithium/polymer electrolyte systems. In this case, the solid electrolyte interface (SEI) consists of the inorganic reduction products of the polymer electrolyte and its impurities. 

Decomposition or alteration of a chemical snbstance by water. (2) In aqueous solutions of electrolytes, the reactions of cations with water to produce a weak base or of anions to produce a weak acid. 

Reaction of Nitriles with Organometallic Reagents Grignard reagents add to a nitrile to give an intermediate imine anion that is hydrolyzed by addition of water to yield a ketone. 

The two-phase titration is based on the reaction of anionic surfactants with cations—normally large cationic surfactants—to form an ion pair. The preferred cationic is benzethonium chloride (Hyamine 1622, 1) because of the purity of the commercially available product. On neutralization of the ionic charges, the ion pair has nonpolar character and can be extracted continuously into the organic phase, e.g., chloroform, as it is formed. The reaction is monitored by addition of a water-soluble cationic dye, dimidium bromide (2), and a water-soluble anionic dye, disulfine blue (3). The cationic dye forms an extractable... 

J.ll In each of the following salts, either the cation or the anion is a weak acid or a weak base. Write the chemical equation for the proton transfer reaction of this cation or anion with water (a) NaC6H50 (b) KCIO (c) C,HSNHCI ... 

J.I3 Na As04 is a salt of a weak base that can accept more than one proton, (a) Write the chemical equations for the sequential proton transfer reactions of the anion with water. Identify the acid and the base in each reaction, (b) If 35.0 g of Na3As04 is dissolved in water to make 250.0 ml. of solution, how many moles of sodium cations are in the solution ... 

The pH of the aqueous solution of an amphiprotic salt is equal to the average of the pKlts of the salt and its conjugate acid. The pH of a solution of a salt of the final conjugate base of a polyprotic acid is found from the reaction of the anion with water. 

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