Reaction mass of Magnesium peroxide and magnesium carbonate and magnesium hydroxide and magnesium oxide

Water solubility

Description of key information

An exact water solubility cannot be determined by measurement of the magnesium

peroxide due to its reactivity when brought into contact with water. Nevertheless, the qualitative measurement of the magnesium content in the test solutions demonstrates that the water solubility of the reaction mass of magnesium carbonate and magnesium hydroxide and magnesium oxide and magnesium peroxide is > 0.010 g/L. More specifically, a water solubility of 0.03136 g/L can determined based on the equilibrium concentration of magnesium in the test solutions.

Key value for chemical safety assessment

Water solubility:

0.031 g/L

at the temperature of:

19.7 °C

Additional information

The flask method was applied for the determination of the water solubility of Reaction mass of Magnesium peroxide, Magnesium hydroxide, Magnesium oxide and Magnesium carbonate. Three mixtures of water and the test substance were stirred for 24, 48 and 96 h whereafter magnesium content, hydrogen peroxide content and pH were measured.

Nominal test substance conc. (mg/l)	Analysed Mg conc. (g/l) after stirring for			Analysed hydrogen peroxide conc. (g/l) after stirring for			pH
	24 h	48 h	96 h	24 h	48 h	96 h
10	0.00388	0.00474	0.00406	0.00201	0.00221	0.0188	10.0-10.2
100	0.0125	0.0117	0.0124	0.00700	0.00903	0.0108	10.7
1000	0.0145	0.0138	0.0132	0.0256	0.0316	0.0396	10.4-10.5

An exact water solubility cannot be determined by measurement of the magnesium peroxide due to its reactivity when brought into contact with water. Nevertheless, an indicative value for the water solubility of the reaction mass of magnesium carbonate and magnesium hydroxide and magnesium oxide and magnesium peroxide can be estimated from the magnesium content.

 

Based on the composition of the reaction mass of magnesium carbonate, magnesium hydroxide, magnesium oxide and magnesium peroxide the maximally attainable magnesium concentration in an aqueous solution can be determined. For the above test concentrations (10, 100 and 1000 mg/L, respectively), the corresponding maximally attainable magnesium concentration is 0.0041, 0.041 and

0.41 g/L, respectively.

 

For the measured magnesium concentrations tabulated above, it is clear that in the 10 mg/L experiment, the maximally attainable magnesium concentration is reached, thus demonstrating that the test chemical is completely dissolved. The water solubility of the reaction mass therefore is > 0.01 g/L.

Moreover, the magnesium concentrations in the 100 and 1000 mg/L experiments suggest that an equilibrium is reached during the experiment. The mean magnesium concentration in these experiments is 0.0130 g Mg/L. From this magnesium concentration, the water solubility of the reaction mass of magnesium carbonate and magnesium hydroxide and magnesium oxide and magnesium peroxide can be back-calculated: 0.031 g/L.