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Physical & Chemical properties

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Appearance/physical state/colour: At room temperature calcium magnesium oxide is a beige powder (reliable data from a GLP guideline compliant study report).

Melting point: > 450 °C (study result, EU A.1 method)

Boiling point: A study does not need to be conducted for solids with a melting point above 300 °C (melting point of this substance: > 450 °C) (cf. section 7.3 Column 2 Annex VII of regulation (EC) 1907/2006).

Relative density: The relative density (compared to water at 4 °C) is D4R = 3.41 (21.6 °C); (study result,EU A.3 method). The deviation from the nominal temperature (20 °C) does not significantly affect the accuracy of the density value.

Particle size distribution: Calcium magnesium oxide (Neutralac QM3): Total Dustiness (airborne fraction): 73.31 mg/g (experimental result, DMT Report). MMAD (bimodal distribution) of airborne fraction: MMAD1 = 6.65 µm (19.9 %) , MMAD2 = 32.27 µm (80.1 %) (distribution fitted to cascade impactor data, percentage in parentheses indicates weighting factor). GSD of MMAD: GSD1 = 2.12 µm, GSD 2 = 1.49 µm. Fractional deposition in human respiratory tract (MPPD model, based on calculated MMAD): Head (ET): 49.2 %; Tracheobronchial (TB): 0.3 %; Pulmonary (PU): 0.9 %. Calcium magnesium oxide 20 - 40 mm: Total Dustiness (airborne fraction): 1.24 mg/g (experimental result, DMT Report). MMAD (bimodal distribution) of airborne fraction: MMAD1 = 5.36 µm (29.9 %) , MMAD2 = 54.01 µm (70.1 %) (distribution fitted to cascade impactor data, percentage in parentheses indicates weighting factor). GSD of MMAD: GSD1 = 1.85 µm, GSD 2 = 4.02 µm. Fractional deposition in human respiratory tract (MPPD model, based on calculated MMAD): Head (ET): 52.0 %; Tracheobronchial (TB): 0.7 %; Pulmonary (PU): 2.0 %

Vapour pressure: Calcium magnesium oxide is a solid with a melting point of > 450 °C. The vapour pressure of solids with a melting point above 300 °C needs not be determined experimentally (cf. section 7.5 Column 2 Annex VII of Regulation (EC) 1907/2006).

Partition coefficient: This study generally does not need to be conducted for inorganic substances (cf. section 7.8 Column 2 Annex VII of Regulation (EC) 1907/2006).

Water solubility of calcium magnesium oxide: 1385.2 mg/L at 20 +/- 0.5 °C(study results, EU A.6 method, recalculated value from calcium and magnesium)

Surface tension: This study only needs to be conducted if, based on the structure, surface activity is expected or can be predicted, which is not the case for this substance: calcium magnesium oxide is not known to exhibit such a structure (hydrophilic head group and hydrophobic tail) (cf. section 7.6 Column 2 Annex VII of Regulation (EC) 1907/2006).

Flash point: This study is only relevant for liquids or low melting point solids, which is not the case for this substance. Further, this study generally does not need to be conducted for inorganic substances (cf. section 7.9 Column 2 Annex VII of Regulation (EC) 1907/2006).

Auto-flammability: The test material shows no relative self-ignition temperature below 400 °C (study result, EU A. 16 method).

Flammability: Non-flammable (study result, EU A.10 method).

Explosiveness: According to the provisions of EU A.14 method, expert judgement considered the test substance to be void of any chemical structures commonly associated with explosive properties.

Oxidising properties: According to the provisions of EU A.17 method, expert judgement considered the test substance as a not oxidising substance.

Stability in organic solvents and identity of relevant degradation products: This study does not need to be conducted for inorganic substances (cf. section 7.15 Column 2 Annex IX of Regulation (EC) 1907/2006).

Dissociation constant: In accordance with section 1, Annex XI of Regulation (EC) 1907/2006 (REACH), this study does not need to be conducted. This property is applicable only for ionisable organic substances. Calcium oxide and magnesium oxide are inorganic salts, which react with water to give a solution of calcium dihydroxide and magnesium hydroxide, respectively. Calcium dihydroxide will completely dissociate to Ca2+ and OH- ions when dissolved in water. Magnesium hydroxide on the other hand will completely dissociate to Mg2+ and OH- ions when dissolved in water. The concept of dissociable functional groups is therefore not applicable. Therefore, the determination of a dissociation constant is not considered to be required (ECHA Guidance on information requirements and chemical safety assessment Chapter R.7a: Endpoint specific guidance, section R.7.1.17).

Viscosity: Viscosity is a property of liquids. Since calcium magnesium oxide is a solid at ambient temperature (ca. 20 °C) such a study does not need to be conducted for this substance (melting point: >450 °C) (in accordance with section 1, Annex XI of Regulation (EC) 1907/2006 (REACH)).

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