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Physical & Chemical properties

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The majority of data on physico-chemical properties of sodium sulfite were taken from handbooks (including CRC Handbook of Chemistry and Physics and the Merck Index).

Studies conducted in accordance with EU guidelines are available for: particle size distribution, auto flammability, flammability and explosive properties.

Waivers are proposed for boiling point, vapour pressure, partition coefficient, surface tension, flash point, oxidising properties, stability in organic solvents, dissociation constant and viscosity, as well as for auto flammability, flammability and explosiveness.

Sodium sulfite (Na2SO3, molecular weight 126.043 g/mol), CAS number 7757-83-7, EC number 231-821-4

Sodium sulfite appears as a white hexagonal crystalline material or as a powder.

Melting point: >900°C (reliable handbook data)

Relative density: 2.63 at 20°C (reliable handbook data)

Particle size distribution and dustiness of a representative sample (experimental study results):

D50 = 246.6 µm

D10 = 102.2 µm

D90 = 466.2 µm

Dustiness: 9.29 mg/g; MMAD (GSD): 26.10 µm (2.04)

Water solubility: 307 g/L at 25°C (very soluble, reliable handbook data)