Solubility product of amorphous magnesium carbonate

The thermodynamic solubility product of amorphous magnesium carbonate (AMC) was studied at room temperature. The samples had been prepared at pH 8.78 and 9.37, where the particle size was 58 ± 11 nm and 49 ± 9 nm, respectively. Solid-state NMR measurements showed that the former contained a minute amount of bicarbonate species, whereas we did not detect any for the latter. While the AMC sample prepared at higher pH exhibited a one-step decomposition at 413°C, the one at lower pH decomposed in two steps at 425 and 510°C. The solubility products of AMC prepared at two pH are statistically identical and the average value is estimated to be 6.3 × 10⁻⁶.