Registration Dossier

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Additional information

Tantalum pentachloride is a hygroscopic yellow-white substance consisting of monoclonal crystals at room temperature. It has a melting point of 216.6 °C and a boiling point of 239 °C, its density is 3.68 g/cm³ at near room temperature. The particle size distribution is as follows:

- >1000 µm: 37.6 % (w/w)

- > 500 and ≤ 1000 µm: 26.6 % (w/w)

- ≤ 500 µm: 35.0 % (w/w)

The measured equilibrium vapour pressure of tantalum pentachloride is 69.9 hPa at 169.3 °C.

Tantalum pentachloride decomposes after contact with water. The concentration of dissolved tantalum – the decomposition product – at the solubility limit upon mixing TaCl5with water, determined in triplicate at nominal loading rates of 8.9- 13.5 g/L varied between 2.0-3.5 g Ta/L (3.92- 6.91 g TaCl5/L).

The results considered most relevant for exposure assessment are those measured from TaCl5 dissolution in water with subsequent pH adjustment as also potential release of the substance to the environment will take place via process waste water which is neutralized prior to entering any sewage treatment plant.

The results from triplicate measurements in water after adjustment to pH 7 range between <0.1 mg Ta/L (LOQ; < 0.198 mg TaCl5/L) and 0.2 mg Ta/L (0.396 mg TaCl5/L).

The substance is considered non-flammable, no self-ignition of the substance can be observed up to temperatures of 400 °C. Furthermore, TaCl5 does not exhibit oxidizing properties.