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Physical & Chemical properties

Vapour pressure

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Reference
Endpoint:
vapour pressure
Data waiving:
study technically not feasible
Justification for data waiving:
other:
Justification for type of information:
Procedure for Vapour Pressure using Dynamic Method

When attempting to transfer the test item into the ebulliometer for analysis it was found that due to the viscosity of the substance and the set-up of the instrument it was not possible to transfer sufficient sample. Even with gentle heating to approximately 80 °C it was not possible to successfully aliquot the sample and therefore it was not technically feasible to perform this analysis.

Discussion

Further preparation of the test item to address this issue was considered, including heating to higher temperatures, however it was not possible to be certain whether this would impact upon the integrity of the test item and any subsequent data acquired.

Alternative methods, including gas saturation were also considered. When performing this method, saturation in the gas phase is of critical importance and due to the inherent nature of the test item, particularly the viscosity, this could not be achieved with absolute confidence and therefore was not considered an appropriate method for this test item.

The boiling temperature for the test item has been determined by an alternative technique as being 289.7 °C and this indicated that the expected vapour pressure would be relatively low.

The vapor pressure of a liquid is the pressure of the vapour in equilibrium with its condensed phase in a closed system and the boiling point of a liquid at a given pressure is the temperature at which the vapour pressure is equal to the given pressure. Therefore, the vapour pressure is a function of the temperature and the boiling point is a function of the pressure such that liquids with higher boiling points will have lower vapour pressures.

Conclusion

Determination of the vapour pressure for the highly viscous test item was “not technically feasible” because the substance could not be loaded into the testing apparatus.

Description of key information

Determination of the vapour pressure for the highly viscous Test Item was “not technically feasible” because the substance could not be loaded into the testing apparatus.

Key value for chemical safety assessment

Additional information