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Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

key study

Study period:

end on 11 August 2005

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The calculation followed the procedures indicated by EU and OECD guidelines.

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Version / remarks:

(only calculation)

Deviations:

no

GLP compliance:

no

Type of method:

other: vapour pressure calculated from the boiling point of the test item

Key result

Temp.:

25 °C

Vapour pressure:

ca. 0 Pa

Remarks on result:

other: 0.00001 Pa or lower

The boiling point of stearic acid was calculated to be approximately 356°C using Meissner’s method. Thus the boiling point of iron oxide isostearate must be above 356°C (which was confirmed experimentally. See section 4.3: boiling point > 400°C).

The vapour pressure of isostearic acid was estimated to be 1.25 x 10E-5 Pa at 25°C based on the boiling point calculated and using the Modified Watson correlation.

 

It is important to note, that the vapour pressure was calculated for the free isostearic acid of the test item. Using the Meissner’s method for the calculation of the boiling point, it is not possible to take into account that the binding of isostearic acid to iron oxide is rather more of covalent nature. The calculation should be regarded as a rough estimation and the real vapour pressure of iron oxide isostearate is expected to be at least several powers to 10 lower than the calculated values.

 

In conclusion, the vapour pressure of iron oxide isostearate is estimated to be <1x10E-5 Pa at 25°C, and therefore being outside of the experimentally measurable range.

Conclusions:

The vapour pressure of iron oxide isostearate is estimated to be < 1 x 10-5 Pa at 25°C.

Executive summary:

As the vapour pressure of the test item is expected to be so small that the value is below the measurement range of an experimental determination, the vapour pressure was calculated according to the procedures indicated by EU and OECD guidelines, and the method calculated the vapour pressure from the boiling point of the test item.

The vapour pressure of iron oxide isostearate is estimated to be < 1 x 10-5 Pa at 25°C.

Description of key information

The vapour pressure of iron oxide isostearate is estimated to be < 1 x 10E-5 Pa at 25°C.

Key value for chemical safety assessment

Vapour pressure:

0 Pa

at the temperature of:

25 °C

Additional information

As the vapour pressure of the test item is expected to be so small that the value is below the measurement range of an experimental determination, the vapour pressure was calculated according to the procedures indicated by EU and OECD guidelines. The resulting report was scored as Klimish 2 and selected as a key study; giving a vapour pressure below 1x10-5 Pa at 25°C.

This value is supported by the experimental data on cerium oxide isostearate which vapour pressure is 2 x 10-6 Pa at 25°C (see the read-across document attached to IUCLID section 13).