Abstract: We prepared magnesium hydroxide by using the ammonia bubbling method. When the temperature ranged from 303.15 K to 353.15 K, we measured the solubility of magnesium chloride in different concentrations of ammonium chloride aqueous solution and deuterium volume fractions of 1.65×10^-4，1.30×10^-4，7.0×10^-5 water and ordinary water. We correlated the solubility data by using Apelblat equation and empirical equation, and calculated the solubility entropy, enthalpy, and standard Gibbs free energy change of magnesium chloride in ammonium chloride aqueous solution by using the modified Van’t-Hoff equation. The results show that under the same solvent conditions, the solubility of magnesium chloride increases with increasing temperature. Under the same temperature conditions, the solubility of magnesium chloride increases sequentially in ammonium chloride solution, ordinary water, and low deuterium water. The higher the concentration of ammonium chloride, the lower the solubility, and the lower the deuterium content, the higher the solubility. The Apelblat equation and empirical equation both show good correlation results, with a total relative error of 0.66%. The entropy change is the main factor affecting the dissolution process of magnesium chloride.

Key words: magnesium chloride,  , low deuterium water,  , ammonium chloride, magnesium hydroxide, solubility,  , entropy change