Aqueous ions

What if the analyte is an aqueous ion, such as Pb + In this case we cannot isolate the analyte by filtration because the Pb + is dissolved in the solution s matrix. We can still measure the analyte s mass, however, by chemically converting it to a solid form. If we suspend a pair of Pt electrodes in our solution and apply a sufficiently positive potential between them for a long enough time, we can force the reaction... 

Aqueous Chemistry. Molybdenum has weU-characterized aqueous chemistry in the five oxidation states, VI, V, IV, III, and II. A listing of aqua ions is given in Table 2. Except for the Mo(VI) species all of the aqua ions are only soluble or stable in acidic media (17). The range of aqueous ions known for molybdenum is far broader than that of other elements. 

Table 2. Aqueous Ions of Molybdenum in Acid Solutions...

Thermodynamic. Thermodynamic properties of Pu metal, gaseous species, and the aqueous ions at 298 K are given in Table 8. Thermodynamic properties of elemental Pu (44), of alloys (68), and of the gaseous ions Pu", PuO", PuO" 27 PuO 2 (67) have been reviewed, as have those of aqueous ions (64), oxides (69), haUdes (70), hydrides (71), and most other compounds (65). 

Absorption Spectra, of Aqueous Ions. The absorption spectra of Pu(III) [22541-70 ] Pu(IV) [22541 4-2] Pu(V) [22541-69-1] and Pu(VI) [22541-41-9] in mineral acids, ie, HCIO and HNO, have been measured (78—81). The Pu(VII) [39611-88-61] spectmm, which can be measured only in strong alkaU hydroxide solution, also has been reported (82). As for rare-earth ion spectra, the spectra of plutonium ions exhibit sharp lines, but have larger extinction coefficients than those of most lanthanide ions (see Lanthanides). The visible spectra in dilute acid solution are shown in Figure 4 and the spectmm of Pu(VII) in base is shown in Figure 5. The spectra of ions of plutonium have been interpreted in relation to all of the ions of the bf elements (83). 

The chemistry of plutonium ions in solution has been thoroughly studied and reviewed (30,94—97). Thermodynamic properties of aqueous ions of Pu are given in Table 8 and in the Uterature (64—66). The formal reduction potentials in aqueous solutions of 1 Af HCIO or KOH at 25°C maybe summarized as follows (66,86,98—100) ... 

Step C 3-Carboxy-4-Hydroxy-8-Tn f/uoromethy/quino/ine - 70 grams of crude 3-car-bethoxv-4-hvdroxv-8-trifluoromethvlquinoline, obtained in Step B, were introduced under an inert atmosphere into a mixture of 300 cc of water and 100 cc of aqueous ION solution of sodium hydroxide. The reaction mixture was heated to reflux and maintained there for 2 hours and forty-five minutes. The solution obtained was poured over a mixture of water, ice and 100 cc of aqueous 11.8N solution of hydrochloric acid. The precipitate thus formed was isolated by filtration, washed with water and introduced into a solution of 20 grams of sodium bicarbonate in 2 liters of water. 

Enthalpy changes for reactions in solution can be determined using standard enthalpies of formation of aqueous ions, applying the general relation... 

Standard molar entropies of elements, compounds, and aqueous ions are listed in Table 17.1 (p. 456). Notice that—... 

NaCIfsj dissolve in water to form aqueous ions, they are considered to be similar. 

These three solids, sodium chloride, calcium chloride, and silver nitrate are similar, hence they are classified together. They all dissolve in water to form aqueous ions and give conducting solutions. These solids are called Ionic solids. 

Silver chloride is a solid that shows this effect. This solid does not dissolve readily in water. When solid silver chloride is placed in water, very little solid enters the solution and there is only a very slight increase in the conductivity of the solution. Yet there is a real and measurable increase—ions are formed. Careful measurements show that even though silver chloride is much less soluble in water than sodium chloride, it is like sodium chloride in that all the solid that does dissolve forms aqueous ions. The reaction is... 

In contrast, solid sodium chloride dissolves readily in water at room temperature and without a large heat effect. This can only mean that the water interacts strongly with the ions—so strongly that aqueous ions are about as stable as are ions in the crystal. In fact, water interacts... 

Again, we see that the alkali metals display likeness in their reactions with water. Furthermore, the reaction products always include an aqueous ion of the alkali element in which one electron has been removed, giving a 1+ ion. 

However they are formed, and from whatever source, aqueous ions are individual species with properties not possessed by the materials from which they came. Furthermore, the properties of a particular kind of ion are independent of the source. Chloride ions from sodium chloride, NaClfsJ, have the same properties as chloride ions in an aqueous solution of hydrochloric acid, HQ. In a mixture of the two, all of the chloride ions act alike none remembers whether it entered the solution from an ionic NaQ lattice or from a gaseous HC1 molecule. 

Water saturated with S02 gas is a relatively mild but quite useful reducing agent. Which of the following aqueous ions might be reduced by it ... 

Many organic compounds are only slightly soluble in water so that non-aqueous ion exchange has an important role in operations with organic substances.21... 

Fuger, J. Oetting, F.L. "The Chemical Thermodynamics of Actinide Elements and Compounds. Part 2. The Actinide Aqueous Ions" International Atomic Energy Agency Vienna, 1976. 

In Zn24, the 3c/-orbitals are filled (du>). Therefore, there can be no electronic transitions between the t and e levels hence, no visible light is absorbed and the aqueous ion is colorless. The dH) configuration has no unpaired electrons, so Zn compounds would be diamagnetic, not paramagnetic. 

In many cases, lanthanide reactions can either be assigned exclusively to one of these two classes, or they show deviations that the classification makes understandable. In Fig. 1.2, we plot the values of AH for the complexing of the tripositive aqueous ions by EDTA (aq), a reaction in which the 4f electrons are conserved. The irregularities are negligible at the chosen scale. Also shown are the values of AH (MCl3,s) which refer to ... 

Similar principles apply to the actinides. The -i-2 oxidation state is present in dipositive aqueous ions and alkaline earth-like dihalides. In the first half of the... 

An example of such a process is the dissolving of ammonium nitrate in water to produce aqueous ions ... 

The equilibrium constant for this reaction is large, indicating that nearly all of the aqueous ions end up as solid precipitate. 

By convention, a solubility equilibrium is written in the direction of a solid dissolving to give aqueous ions, and the equilibrium constant for this reaction is called the solubility product ( sp). Here, for example, is the reaction... 

Earlier chapters described how metal salts dissolve in water to give solutions of aqueous ions. Here are three... 

This paper describes the successful incorporation of molybdenum and molybdenum-nickel clusters into zeolites with 12-membered ring by aqueous ion exchange and application of the resulting materials to HDS reaction of benzothiophene. Stoichiometry of the ion exchange was examined by elemental analysis. UV-visible spectroscopy and EXAFS measurements were carried out to investigate the structure of molybdenum species loaded on zeolites. 

Gunn. S. R. Thermodynamics of the Aqueous Ions of Americium. Diss. 

Lohr, H. R. Heats of Formation of Some Aqueous Ions of Americium. 

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