Registration Dossier

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Additional information

Appearance: Barium hydroxide is a white powder (reliable handbook data)

Melting point: 392 °C (guideline study)

Boiling point. This study does not need to be conducted for solids with a melting point above 300°C (melting point of this substance: 392 °C) (cf. Annex VII section 7.3 Column 2 of regulation (EC) 1907/2006).

Relative density: Relative density: 3.74 at room temperature (barium hydroxide monohydrate) (reliable handbook data)

Particle size distribution/dustiness: Barium hydroxide monohydrate: MMAD 32.76 µm GSD 1.57 µm

Barium hydroxide monohydrate: D50 195.3 µm (Laser diffraction)

Vapour pressure: This study does not need to be conducted for solids with a melting point above 300°C (melting point of this substance: 392 °C) (cf. Annex VII section 7.5 Column 2 of regulation (EC) 1907/2006).

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

Water solubility of barium hydroxide: 37.4 g/L at 20 °C (HSDS) and 49.1 g/L at 25°C (CRC handbook). The water solubility of the test substance is dependent on temperature (> 3%/°C according to Gmelin _1932 - supporting study).

Surface tension: This study only needs to be conducted if based on the structure surface activity is expected or can be predicted (cf. Annex VII section 7.6 Column 2 of regulation (EC) 1907/2006): According to EU Directive 648/2004 (CEC, 2004). Surfactant means any organic substance and/or preparation used in detergents, which has surface-active properties and which consists of one or more hydrophilic and one or more hydrophobic groups of such a nature and size that it is capable of reducing the surface tension of water, and of forming spreading or adsorption monolayers at the water-air interface, and of forming emulsions and/or microemulsions and/or micelles, and of adsorption at water-solid interfaces. Therefore, the substance barium hydroxide could be regarded as non surface active substance and the study should not be conducted.

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. Annex VII section 7.9 Column 2 of regulation (EC) 1907/2006).

Auto-flammability: Self-ignition is not considered to be of relevance for this substance, since this would require heat to be developed either by reaction of this substance with oxygen or by exothermic decomposition and which is not lost rapidly enough to the surroundings (in accordance with section 1 of REACH Annex XI). A DSC analysis in an open test vessel results in no exothermic reaction up to 400°C. Since barium hydroxide represents the highest oxidised form of barium it is intrinsically not combustible and can safely be assumed not to be ignitable under the conditions given Test N4 Part III, sub-section 33.4.1.6 of the “UN Recommendations on the Transport of Dangerous Good, Manual of Tests and Criteria”. In conclusion, the conduct of further experimental verification is not considered to be required.

Flammability-pyrophoric properties: Testing for pyrophoric properties of solids is not considered to be required, since this substance is stable at ambient temperature. This substance also does not contain any chemical groups that might lead to spontaneous ignition a short time after coming in contact with air at room temperature (circa 20°C). Furthermore, long-term industrial experience in handling shows that the substance does not ignite in contact with air (in accordance with section 1 of REACH Annex XI).

Flammability in contact with water: Testing of flammability in contact with water is not considered to be required, because the substance does not contain groups that might lead to a reaction with water or damp air, leading to the development of dangerous amounts of gas or gases which may be highly flammable. Furthermore, long-term industrial experience in practical handling of the substance shows that it does not react with water, and recent experimental testing for water solubility has also not reported any formation of gases (in accordance with section 1 of REACH Annex XI).

Flammability solids (metal salts): Testing of flammability is not considered to be required for inorganic metal salts in which (i) the cation is in its highest possible oxidation state (e.g. Ba2+) and which therefore is incapable of further reaction with oxygen, and (ii) the anionic component is similarly not capable of further reaction with oxygen. This substance can thus be designated as non-flammable. (Guidance on information requirements and chemical safety assessment Chapter R.7a: Endpoint specific guidance, section R.7.1.10.3).

Explosiveness: This substance is void of any chemical structures commonly associated with explosive properties, such as metal peroxides, peroxo-acid-anions, azides, and halogen oxides.) Further, it is noted that despite long-term industrial use of the substance, it is not classified for explosive properties according to UN transport regulations (cf. Annex VII section 7.11 Column 2 of regulation 1907/2006).

Oxidising properties: This test item does not contain a surplus of oxygen or any structural groups known to be correlated with a tendency to react exothermally with combustible material (cf. Annex VII section 7.13 Column 2 of regulation 1907/2006).

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

Dissociation constant: The substance does not contain relevant functional groups for which an assessment of the dissociation behaviour would provide information for risk assessment purposes. Therefore, the determination of a dissociation constant is not considered to be required (Guidance on information requirements and chemical safety assessment Chapter R.7a: Endpoint specific guidance, section R.7.1.17.1).

Viscosity: Viscosity is a property of fluids. Since Barium hydroxide is a solid at ambient temperature (ca. 20°C) such a study does not need to be conducted for this substance (melting point: 408 °C) (in accordance with section 1 of REACH Annex XI).

Additional information: The pH value of a 10% test item solution is determined at pH 13.0