Table 4.
The precipitation of insoluble calcium orthophosphates. The activity products (Q) and the solubility products Ksp (at 37 °C) are obtained from the literature.
| Formula | Activity Product (Q) | Solubility Product, Ksp at 37 °C | Ref. | |
|---|---|---|---|---|
| BRU | CaHPO4 | {Ca2+} {HPO42−} | 2.34 × 10−7 * | [129] |
| 2.26 × 10−7 | [134] | |||
| 0.92 × 10−7 | [135] | |||
| OCP | Ca8(HPO4)2(PO4)4 | {Ca2+}8 {H+}2 {PO43−}6 | 1.25 × 10−96 * | [129] |
| 1.20 × 10−97 | [134] | |||
| 3.98 × 10−98 | [136] | |||
| 2.51 × 10−99 | [137] | |||
| ACP | CaxHy(PO4)z | {Ca2+}x {H+}y {PO43−}z | 2.0 × 10−26 *† | [130] |
| {Ca2+}3 {PO43−}2 | 2.0 × 10−33–1.6 × 10−25 | [29] | ||
| {Ca2+} {H+}0.22 {PO43−}0.74 | 2.3 × 10−11, 3.2 × 10−12 § | [138] | ||
| CDHA | Ca10-x(HPO4)x(PO4)6-x(OH)2-x | {Ca2+}10−x {H+}x {PO43−}6 {OH−}2−x | ~7.94 × 10−86 * | [130] |
| HA | Ca10(PO4)6(OH)2 | {Ca2+}10 {PO43−}6 {OH−}2 | 1.00 × 10−118 | [29] |
| 6.31 × 10−118 * | [129] | |||
| 2.00 × 10−119 ‡ | [139] | |||
| 2.51 × 10−111 | [140] | |||
| 5.42 × 10−119 | [141] | |||
| ClA | Ca10(PO4)6Cl2 | {Ca2+}10 {PO43−}6 {Cl−}2 | 3.98 × 10−116 * | [140] |
| CO3A | Ca10(PO4)6CO3 | {Ca2+}10 {PO43−}6 {CO32−} | 1.58 × 10−103 *‡ | [139] |
* Values used in the calculations presented in this work; † Ksp is pH-dependent, value in the table for pH = 7.4; ‡ Ksp obtained at 25 °C; § authors observed two different metastable phases.