Inorganic ions aqueous solution

Most trivalent rare earth ions have no or very weak absorption in the visible range [8]. For example, Y +, La +, Gd +, Yb +, and Lu + in inorganic acid aqueous solutions are colorless. It is worth noting that colors of the aqueous solutions for ions having the 4f electronic configuration are usually similar to those that have the 4f " " configuration (Figure 1.7). 

Phenyldiazonium chloride and other similar diazonium compounds are very soluble in water, are completely insoluble in ether and other organic solvents, and are completely dissociated in aqueous solution to organic cations and inorganic anions (e.g., chloride ions) a convenient formulation is therefore, for example, CjHjNj+CP. 

Ch oline in the form of choline base (hydroxide) is a strong organic base with a pH of approximately 14. This product can have industrial apphcations where it is important to replace inorganic bases with organic materials. Ch oline base is currently used in the formulation of photoresist stripping products for use in the printed wire board industry. Dilute aqueous solutions (5%) of ch oline base that have very low concentrations of metallic ions have been utilized for apphcations in the semiconductor industry. 

In the case of inorganic solutes we are concerned largely with samples in aqueous solution so that it is necessary to produce substances, such as neutral metal chelates and ion-association complexes, which are capable of extraction into organic solvents. For organic solutes, however, the extraction system may sometimes involve two immiscible organic solvents rather than the aqueous-organic type of extraction. 

It is very common for inorganic chemists to neglect or ignore the presence of solvent molecules coordinated to a metal centre. In some cases, this is just carelessness, or laziness, as in the description of an aqueous solution of cobalt(ii) nitrate as containing Co ions. Except in very concentrated solutions, the actual solution species is [Co(H20)6] . In other cases, it is not always certain exactly what ligands remain coordinated to the metal ion in solution, or how many solvent molecules become coordinated. Solutions of iron(iii) chloride in water contain a mixture of complex ions containing a variety of chloride, water, hydroxide and oxide ligands. 

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