Solubility in acidic solution

Fumarates. lron(Il) fumarate [141 -01 -5], Fe(C4H20, is prepared by mixing hot aqueous solutions of sodium fumarate and iron(Il) sulfate followed by filtration of the resulting slurry. It has limited solubiUty in water but is more soluble in acid solution. The compound is red-orange to red-brown and finds uses as a hematinic. A non stoichiometric compound [7705-12-6] and iron(Ill) fumarate [52118-11-3], Fe2(C4H20 3, are also available. 

Thus, many salts are more soluble in acidic solution than in pure water. In addition to the carbonates, important examples include the phosphates (POq ) and the sulfides (S ). Insoluble hydroxides also dissolve in acidic solution, as illustrated by magnesium hydroxide ... 

Among these less well-known addition patterns are oxo-tetraamino-[60]fijllerenes like 23 and 24 containing four permanent or pH-dependent positive charges (Witte et al., 2007). Compound 23 is very well soluble in water over a wide pH range by virtue of its four permanent trimethyl ammonium groups, whereas 24 is only slightly soluble in acidic solutions (pH 4) but well dissolvable in polar solvents like methanol or ethanol. 

Free and glycine-conjugated BAs are only slightly soluble in acid solutions. As the pH is increased, the solubility will increase. This is a very important characteristic since it describes the solubility characteristics of the major BAs, and, it also explains their potential to enter the epithelium at physiological pH ranges. 

When the collagen rod can be extracted in the native form it is soluble in acidic solutions, at room temperature. If the solutions are heated, the collagen is denaturated the chains lose their helical conformation. The characteristic temperature of this helix —> coil transition is around 36 C. The solution then contains principally single chains, but also some double and triple chains which were initially covalently bound and some sub-units of the single chains. This product is gelatin. 

Applications of precipitation titrations are listed in Table 7-1. Whereas the Volhard method is an argentometric titration, the Fajans method has wider applications. Because the Volhard titration is carried out in acidic solution (typically 0.2 M HN03), it avoids certain interferences that affect other titrations. Silver salts of CO -, C20 -, and AsO " are soluble in acidic solution, so these anions do not interfere. 

In its precipitation reactions ameiicium(IIl) is very similar to the other tripositive actinide elements and to the rare earth elements. Thus the fluonde and the oxalate are insoluble and the phosphate and iodate are only moderately soluble in acid solution, whereas the nitrates, halides, sulfates, sulfides, and perchlorates are all soluble. Americium(VI) can be precipitated with sodium acetate giving crystals isostructural with sodium uranyl acetate,... 

Studies on porphyrins in aqueous solution are complicated by their lack of solubility (in acidic solutions) and their tendency to associate (in basic solutions). These difliculties may be overcome by using soluble porphyrins with carboxylate or sulfonate substituents, although the uroporphyrins are convenient to study as they are freely soluble, and do not aggregate at concentrations necessary for many solution studies. 

PROBLEM 16.26 Which of the following compounds are more soluble in acidic solution than in pure water ... 

It is unclear how accurate this method is for the determination of lignin content in grasses, since a fraction of the lignin from grasses appears to be readily soluble in acidic solutions, such as used in this procedure. This would result in underestimation of the actual lignin content (Hatfield and Fukushima, 2005). 

Because Ru02 is not soluble in acidic solutions, only the ruthenium that is not in the zeolite as Ru02 will be dissolved during the acid digestion used in the ICP/MS analysis. The solutions above the undissolved RuC>2 particles were analyzed and the results indicate that only 3% of the ruthenium is not incorporated into Ru02 particles in the calcined RuY samples. 

Solubility can also be affected by pH. Salts whose anions are basic will increase in solubility in acidic solutions. This is because the anions will combine with excess hydrogen ions. According to Le Chatelier s Principle, this will shift the equilibrium to the right to restore equilibrium. 

Carbonate minerals are easily calcined to the oxide. They are also soluble in acidic solutions and form the salt of that acid. This offers many possibilities for purification prior to extraction by one of the prepared menstruums. Using a strong vinegar to produce the acetate of the metal is often the preferred way and this subject will be examined later. The extraction of the mineral takes place much as in the Vegetable work, by covering the subject with menstruum, sealing and digesting in a warm place up to about 90°C. 

It is also soluble in acid solutions containing thiourea, which stabilizes Cu1 as a complex acid thiourea solutions are also used to dissolve copper deposits in boilers. 

Aminosulfonic and carboxylic acids can be diazotized in the normal way if they are readily soluble in acid solution. Usually, however, this... 

The literature review in Chapter 2 reveals that divalent metal oxides such as oxides of calcium, magnesium, and zinc (CaO, MgO, and ZnO) are the major candidates for forming phosphate ceramics. These oxides are sparsely soluble in acidic solution, and as we shall see in Chapter 4, they are the most suitable ones to form ceramics. In addition, following the methods discussed in subsequent chapters in this book, aluminum oxide (alumina, AI2O3) and iron oxide (Fe203), which are abundant in earth s crust have excellent potential to form low cost CBPCs. For this reason, we have provided relevant information on these oxides. Table 3.2 gives some details. 

Slightly soluble in water, but less soluble in acid solutions freely soluble in most organic solvents. 

Acidic dmgs such as the nonsteroidal antiinflammatory agents, are less soluble in acidic solutions than in alkaline solutions because the predominant undissociated species cannot interact with water molecules to the same extent as the ionised form, which is readily hydrated. 

Basic dmgs such as ranitidine are more soluble in acidic solutions, where the ionised form of the dmg is predominant. If is the solubility of an undissociated base, RNH2, the expression for the solubility (5) as a function of pH can be obtained as follows. 

Ozone is more soluble in acid solutions than in alkaline solutions (10), and dissolves in dilute acid with a rapid pH rise. This solution holds the dissolved ozone in solution longer than is possible in higher pH solutions, where hydroxyl ion catalyzes the decomposition. As the ozone decomposes, pH falls back to the original value. Figure 5... 

As the solution is made more acidic, the concentration of hydroxide ion decreases, causing an increase in the concentration of Zn (aq) ion. Zinc hydroxide is thus more soluble in acidic solution than in pure water. 

The presence of salts that share a common ion to the constituent ions of a solute will affect the solubility of a solute. Because of Le Chatelicr s principle, the addition of common ions shifts the equi librium toward the formation of additional solute (solid), which decreases its solubility. Solubility can also be affected by pH. Salts whose anions are basic will increase in solubility in acidic solutions. This is because the aiuons will combine with excess hydrogen ions. According to Le Chatelier s principle, this will shift the equilibrium to the right to restore equilibrium. 

During exposure, galvanized steel and weathering steel are expected to corrode by forming a protective surface film that retards corrosion. The rate of corrosion would then be diffusion controlled and depend upon the thickness of the film. Many of the corrosion products, particularly the carbonates, hydroxides, etc. within the film are soluble in acid solutions. In environments where increased acidity is present, dissolution of the protective film is a competing mechanism that accelerates the rate of corrosion of metals. 

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