Solubility equilibria windows

Also, from the figure, the lowest solubility of Mg in equilibrium with Mg(OH)2 occurs at about pH 10.4 raising the pH above this value does not affect the solubility, since the solubility is already zero at pH 10.4. At this value of pH, the solubility of Ca in equilibrium with CaC03 is not affected very much. Also, lowering the pH to below 9.8 practically dissolves the Mg(OH)2. Thus, these two limiting conditions leave only a very small window of pH 9.8 to 10.4 for an optimal concurrent precipitation of Ca and Mg. Above pH 10.4, the precipitation of CaC03 suffers and below pH 9.8, the precipitation of Mg(OH) suffers. 

In the case of slow reactions, the transformation rate is limited by intrinsic kinetics. A drastic increase of the temperature allows exponential acceleration of the reaction rate in agreement with the Arrhenius Law. Moreover, the pressure can be advantageous to accelerate reactions, to shift equilibrium, to increase gas solubility, to enhance conversion and selectivity, to avoid solvent evaporation, and to obtain single-phase processes [8, 13]. The overall transformation rate of such reactions could be significantly increased in these wove/ operating windows. 

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