Aqua species of beryllium

In 2008, 159 Mt of gypsum was produced by mining worldwide. A second source referred to as synthetic gypsum is produced in the flue gas desulfurization processes described in Box 12.2. The contribution made by synthetic gypsum to world supplies is growing in importance, and its production is 

The Yoshino gypsum plant in Japan recycling gypsum wallboards is an integral part of the manufacturing process which produces new gypsum plasterboards. 

In contrast to the coordination number of four in the aquated Be ion, each of the later group 2 metal ions can accommodate six or more water molecules in the first coordination sphere. In solution ( 0-labelled water), NMR spectroscopic data are consistent with the presence of [Mg(OH2)6], and crystallographic data on a range of salts confirm that this complex ion is octahedral. The [Mg(OH2)6] ion dissociates to some extent in aqueous solution (pATa = 11.44). 

In solution, the coordination number of the [Ca(OH2) ] ion depends on the concentration with 6. In the solid state, octahedral [Ca(OH2)6] is present in crystalline CaCl2 6H2O and CaBr2-6H20, and a number of salts containing [Ca(OH2)7] have been structurally characterized. The geometry of the cation varies, e.g. pentagonal 

Complexes with ligands other than water 

8 Complex ions in aqueous solution Aqua species of beryllium 

Using O-labelled water, it is possible to confirm the hydration number in [Mg(H20)6] by use of NMR spectroscopy, but for the aqua ions of Ca +, Sr + and Ba, exchange between coordinated water and solvent is too fast on the NMR timescale for such studies. An octahedral coordination sphere has been established for [Mg(H20)g] in a number of crystalline salts, and also for [Ca(H20)g] +. The [Mg(H20)g] + ion dissociates to some extent in aqueous solution, but hydrated cations of the later metals are not appreciably ionized and solutions of their salts derived from strong acids are neutral. 

In 2004, 110Mt of gypsum was produced worldwide. Within the US in 2004, 29.5 Mt of prefabricated gypsum products were sold or used, and the chart below shows the distribution of products making up this total. The average new home in the US contains 570m of gypsum wallboard. 

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