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Date: 5-4-2017
2019
Date: 27-4-2019
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Date: 25-6-2020
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Hydroxides of e group 2 metals
Beryllium hydroxide is amphoteric and this sets it apart from the hydroxides of the other group 2 metals which are basic. In the presence of excess [OH]-, Be(OH)2 behaves as a Lewis acid forming the tetrahedral complex ion but Be(OH)2 also reacts with acids.
The water solubilities of M(OH)2 (M = Mg, Ca, Sr, Ba) increase down the group, as do their thermal stabilities with respect to decomposition into MO and H2O. Magnesium hydroxide acts as a weak base, whereas Ca(OH)2, Sr(OH)2 and Ba(OH)2 are strong bases. Soda lime is a mixture of NaOH and Ca(OH)2 and is manufactured from CaO and aqueous NaOH; it is easier to handle than NaOH and is commercially available, being used, for example, as an absorbent for CO2, and in qualitative tests for [NH4]+ salts, amides, imides and related compounds which evolve NH3 when heated with soda lime.
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