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Physical & Chemical properties

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Administrative data

Description of key information

Additional information

Purity

Typically the purity of magnesium is 81% (dry weight, after excluding water).

Impurities in the substance: The substance may contain the impurities indicated below, derived from the production process, each one present at the concentrations indicated below

Magnesium hydrogen orthophosphate, EINECS 231-823-5

< 20 %

 

All other impurities > 1 % are other inorganic phosphates or other related inorganic substances which do not significantly affect the substance’s toxicological and ecotoxicological properties.

Impurity profile is specific to each registrant. 

Physico-chemical properties

Magnesium bis(dihydrogenorthophosphate) has a melting point of >450°C.

The water solubility of the test material has been determined to be at least 221 g/l of solution at 20.0 ± 0.5°C. However, the solubility of the test material was demonstrated to be extremely sensitive to the nominal loading rate of the solution, as demonstrated by the results in the following table:

 

Nominal loading rate (g/l)

Equivalent test material concentration (g/l)

Typical solution pH

5.0

3.68

5.2 to 5.7

16.7

11.5

4.5 to 5.2

50

36.1

3.9

100

67.6

3.7

200

117

3.4

400

221

3.0

 

Investigation into the influence of the pH range 4 to 9 on the solubility of the test material was performed, but in each case the test material demonstrated acidic characteristics on dissolution, overwhelming the capacity of the buffer solutions to give solution pH’s approximately equal to those observed using un-buffered water. Therefore, as the buffering capacity of the solutions used was considered to exceed that of the environment, the solubility of the test material was considered to be independent of the initial pH range 4 to 9, resulting in a consistent acidic solution capable of overwhelming any weak to moderate buffering capacities present.

Finally, although a definitive value for water solubility could not be determined, testing carried out did indicate that the influence of temperature on the observed solubility was not significant.

 

Magnesium bis(dihydrogenorthophosphate) is not considered to possess any of the following hazardous physico-chemical properties: autoflammability and/or self-ignition, flammability, explosiveness and oxidising properties