Registration Dossier

Diss Factsheets

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Additional information

The substance Chlorine-dioxide (EC 233-162-8, CAS 10049-04-4, ClO2) is an unstable oxidizing gas only generated in-situ and used at less than 2%w/w in water. Water is acting as a stabilizing agent against explosive/oxidizing properties. The highest possible recognized concentration which guarantees safe handling of the substance is 2-3%w/w in aqueous solution at 25 ° C under  a reduced pressure of 4600 Pa.


Therefore the substance registered in this dossier is the solution generated in-situ at less than 2%w/w in water. At this concentration, some of the physico-chemical properties of the registered substance are anticipated to be similar to the solvent.


Other physico-chemical properties are anticipated from available litterature data on the gaseous form of the substance. Note also that solubility is correlated to the pressure over the solution (and temperature), and in certain conditions, off-gassing may occur. Despite the solution should not be classified as hazardous as such, this phenomenon may lead to violent reaction as the gas is oxidising.


For that reason, available data on the pure gaseous substance and on the Solution generated in-situ at less than 2%w/w in water (as registered) were discussed in this dossier and summarized as follows:



























































































 



Solution of chlorine dioxine generated in-situ at less than 2% in water


(as registered)



Pure substance


(not registered as such, due to unstability)



Physical state at 20°C and 1013 hPa



Liquid


Yellow


with a chlorine-like odour, expected to be perceptible, if not in closed systems.


(visual observation)



Gas


green-yellow to orange-red depending on concentration with chlorine-like pungent odour. (literature data)



Melting point / freezing point



<= 0°C (close to the MP of water)


(waiving : expert statement)



-59°C at reduced pressure (10 mm Hg = 1333 Pa). (exp. Data & literature data)



Boiling point



<= 100°C (close to the BP of water)


(waiving : expert statement)



11°C at atm. P (1013 hPa)


(exp. Data & literature data)



Density



1 (close to the relative density of water)


theoretical relative density : 1.008


 



relative density : at 0°C (liquid) - 1.64


(exp. Data & literature data)



Particle size distribution (Granulometry)



Waiving (liquid)


(waiving : expert statement)



Waiving (gas)


(waiving : expert statement)



Vapour pressure



Vapour pressure is a function of temperature and


concentration.


Calculated ClO2 partial pressure at 20°C over 20 g/L = 22900 Pa


(literature data)



At 0°C, the calculated value between 65.3 and 68.1 kPa.


(literature data)


 



Partition coefficient



Waiving (inorganic substance)


(waiving : expert statement)



Waiving (inorganic substance)


(waiving : expert statement)


-3.22 (QSAR : Estimated value)



Water solubility



The substance as registered should be fully soluble in water but Water solubility is a function of temperature and


partial pressure (off-gassing).


(waiving : expert statement - see also comment on pure ClO2)


 



Water solubility is a function of temperature and


partial pressure (off-gassing).


Concentrations up to 60 g/L or more can be reached (parameters not specified), but unstable. Typically, 3 g/L at 25°C and 4600 Pa seems to be recognised as stable and safe.



Surface tension



Waiving (chemical structure)


(waiving : expert statement)



Waiving (chemical structure)


(waiving : expert statement)



Flash point



Waiving (inorganic substance)


(waiving : expert statement)



Waiving (gaseous inorganic substance)


(waiving : expert statement)



Auto flammability



Waiving (release the gas if heated - EUH018 proposed)


(waiving : expert statement)



Waiving (explosive substance)


(waiving : expert statement)



Flammability


 



Waiving (This endpoint does not apply to the substance as registered (aqueous solution generated in-situ), as liquid.)


(waiving: expert statement)



The gas has a Harmonised Classification as Oxidising, therefore it does not need to be classified in any other hazard class.


Chlorine dioxide gas: LEL = 4 (sparks) - 10 (any source of ignition) %v/v in air.



Explosiveness



For chlorine dioxide in aqueous solution, no physical hazard is established in the harmonised entry.


However, based on the potential hazard if off-gassing, the EUH018 phrase is proposed.


(literature data / expert statement)



The gas is well-known to be sensitive to various sources of ignition (heat, light, shock, and in particular sparks), and is characterised by an induction period.


However, the gas has a Harmonised Classification as Oxidising, therefore it does not need to be classified in any other hazard class.


(literature data provided).



Oxidising properties



Waiving : not considered to be oxidising, but potential hazard if off-gassing.


(waiving: expert statement & Literature data)



CLH : Ox. Gas 1, H270: May cause or intensify fire; oxidiser.


(waiving : expert statement)



Dissociation constant



Waiving (no ionization anticipated)


(waiving : expert statement)



Waiving (no ionization anticipated)


(waiving : expert statement)



Viscosity



ca 1 mPa.s at 20°C (close to the viscosity of pure water)


(waiving : expert statement)



Waiving (gas)


(waiving : expert statement)