Group aqueous solution chemistry

The aqueous solution chemistry of Al and the other group 13 metals is rather complicated. The aquo ions are acidic with... 

Pyridinecarboxaldehyde, 3. Possible hydration of the aldehyde group makes the aqueous solution chemistry of 3 potentially more complex and interesting than the other compounds. Hydration is less extensive with 3 than 4-pyridinecarboxaldehyde but upon protonation, about 80% will exist as the hydrate (gem-diol). The calculated distribution of species as a function of pH is given in Figure 4 based on the equilibrium constants determined by Laviron (9). 

The aqua ions (M = Al, Ga, In, Tl) are acidic (see equation 6.34) and the acidity increases down the group. Solutions of their salts are appreciably hydrolysed and salts of weak acids (e.g. carbonates and cyanides) cannot exist in aqueous solution. Solution NMR spectroscopic studies show that in acidic media, Al(III) is present as octahedral [Al(H20)g], but raising the pH leads to the formation of polymeric species such as hydrated [Al2(OH)2] and [Al7(OH)ig] +. Further increase in pH causes Al(OH)3 to precipitate, and in alkaline solution, the aluminate anions [A1(0H)4] (tetrahedral) and [Al(OH)g] (octahedral) and polymeric species such as [(H0)3Al(p-0)Al(0H)3] are present. The aqueous solution chemistry of Ga(III) resembles that of Al(III), but the later metals are not amphoteric (see Section 12.7). 

Aqueous solution chemistry involving cations of the group 14 elements is restricted mainly to Sn and Pb (see Section 13.13), and so Table 13.1 gives E° values only for these metals. 

Many aspects of the aqueous solution chemistry of the group 15 elements have already been covered ... 

Further, there is little difference in energy between the various oxidation state species of sulfur, a fact that is doubtless involved in the complicated oxoacid and oxoanion chemistry of sulfur. We have already discussed some aspects of the aqueous solution chemistry of the group 16 elements ... 

The Group 13 metals differ sharply from the non-metallic element boron both in their greater chemical reactivity at moderate temperatures and in their well-defined cationic chemistry for aqueous solutions. The absence of a range of... 

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