Solubility Characteristics of MgO and Its Reaction with Acid Phosphates

SOLUBILITY CHARACTERISTICS OF MgO AND ITS REACTION WITH ACID PHOSPHATES 

As discussed in Chapter 3 (also see Ref. [23]), MgO and Mg(OH)2 are sparsely soluble and their dissolution reactions are given by 

Correspondingly, as we have seen in Table 5.1, the pH dependence of the ionic concentration of Mg in an acidic solution, i.e., Mg (aq)), is given by 

These equations were used to plot the pH dependence of log(Mg +(aq)) in Fig. 5.2. 

The plots in Fig. 5.2 show that (Mg (aq)) decreases linearly as the pH increases. Thus, its solubility in H3PO4 solution is high, but will be significantly less if acid phosphate solutions of higher pH are used to form the ceramics. For this reason, as stated above, acid phosphate salts are used in fabrication of almost all Mg-phosphate ceramics. 

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