Calcium acetylide

Vapour pressure

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

equivalent or similar to guideline

Guideline:

other: not reported

GLP compliance:

not specified

Type of method:

other: not reported

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

0 mm Hg

Conclusions:

A vapour pressure value of 1.32E-033 mm Hg at 25°C is reported in a handbook or collection of reliable data (SRC PhysProp Database, 2000) which has been subject to peer-review and in which the original data sources are traceable. The result is considered to be reliable.

Executive summary:

A vapour pressure value of 1.32E-033 mm Hg at 25°C is reported in a handbook or collection of reliable data (SRC PhysProp Database, 2000) which has been subject to peer-review and in which the original data sources are traceable. The result is considered to be reliable. In SI units this corresponds to a vapour pressure of 1.76E-31

Reference 2

Endpoint:

vapour pressure

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

As calcium carbide instantly hydrolyses to Ca(OH)2 and C2H2 upon contact with water/moisture the assessment is based on the degradation products. For details please refer to the read across report in section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

40 400 mm Hg

Remarks on result:

other: Vapour pressure of degradation product

Conclusions:

Acetylene is one of the degradation products of Calcium acetylide. The vapour pressure of acetylene is 40400 mm Hg at 25 °C.

Executive summary:

Acetylene is one of the degradation products of Calcium acetylide. The vapour pressure of acetylene as cited in the Hazardous Substances Data Bank (HSDB) is 40400 mm Hg at 25 °C. Physico-chemical data form HSDB is peer-reviewed and thus considered to be reliable.

This information is used in a read-across approach in the assessment of the target substance. For justification of read-across please refer to the read-across report attached to IUCLID section 13.

Description of key information

Calcium carbide instantly decomposes hydrolytically upon contact with water,

yielding acetylene and calcium dihydroxide. Therefore, the vapour pressures of these degradation products are the relevant parameters for the environmental risk assessment. The vapour pressure of calcium hydroxide is negligible and is not further considered. For environmental risk assessment, the vapour pressure of acetylene is considered to be the critical parameter, whereas for human health risk assessment (worker exposure to dust) calcium carbide itself will be evaluated, and the vapour pressure set to the minimum accepted value.

Key value for chemical safety assessment

Vapour pressure:

0 Pa

at the temperature of:

25 °C

Additional information

For calcium carbide a vapour pressure value of 1.32E-033 mm Hg at 25°C is reported in a handbook or collection of reliable data (SRC PhysProp Database, 2000) which has been subject to peer-review and in which the original data sources are traceable. The result is considered to be reliable.

However, as the substance instantly decomposes hydrolytically upon contact with water, yielding acetylene and calcium dihydroxide, the vapour pressures of these degradation products are relevant for risk assessment.

The vapour pressure of acetylene as reported in the Hazardous Substances Data Bank (HSDB) is 4.04 x 10^4 mm Hg at 25 °C (Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989). This value corresponds to 53862 hPa at 25 °C.

The vapour pressure of calcium hydroxide is considered to be negligible as the substance has a melting point > 300 °C.

Thus the vapour pressure of acetylene is considered to be the critical parameter for chemical safety assessment (environment), whereas the negligible vapour pressure of calcium carbide itself is taken into account in human health risk assessment.

This information is used in a read-across approach in the assessment of the target substance. For justification of read-across please refer to the read-across report attached to IUCLID section 13.