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Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Version / remarks:
23.03.2006
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
static method
Temp.:
20 °C
Vapour pressure:
342 Pa
Remarks on result:
other: 10 pairs temperature/vapour pressure were used to calculate a regression from which vapour pressure at ambient temperature was estimated.
Temp.:
25 °C
Vapour pressure:
395 Pa
Remarks on result:
other: 10 pairs temperature/vapour pressure were used to calculate a regression from which vapour pressure at ambient temperature was estimated.

Measurement Values: The measured values are presented in the following table.

Measurement Values, Date: 10. Mar. 2020

1. Determination increasing temperature

2. Determination decreasing temperature

Temp. in °C

Time

Pressure in hPa

Temp. in °C

Time

Pressure in hPa

20.0

10:00

3.2

48.0

13:20

7.2

29.0

10:43

4.5

38.9

14:00

6.0

38.0

11:20

5.6

29.9

14:24

4.9

47.0

12:05

6.9

21.0

15:00

3.5

55.0

12:49

8.2

16.0

15:19

3.0

 

CALCULATION OF RESULTS

From the measured values for the increasing and for the decreasing temperature, log p (in log Pa) and 1/T (in 1/K) were calculated. The measured and the calculated values were plotted (p against T and log p against 1/T). The regression curve with slope B, intercept A and correlation r was calculated (graph log p vs. 1/T). From the values of these parameters, vapour pressures at 20.0 and at 25.0 °C were calculated using the following equation: log p = (B*1/T) + A which can be transformed as follows: p(20 °C) = 10 EXP [(B+1/293.15)+A] and p(25 °C) = 10 EXP [(B+1/298.15)+A]

RESULTS

The calculation results are presented in the following table:

n

Temperature T

Pressure p

Temperature T

1/T

log p

°C

hPa

K

1/K

log Pa

1

20.0

3.2

293.15

0.00341122

2.5051

2

29.0

4.5

302.15

0.00330961

2.6532

3

38.0

5.6

311.15

0.00321388

2.7482

4

47.0

6.9

320.15

0.00312354

2.8388

5

55.0

8.2

328.15

0.00304739

2.9138

6

48.0

7.2

321.15

0.00311381

2.8573

7

38.9

6.0

312.05

0.00320461

2.7782

8

29.9

4.9

303.05

0.00329979

2.6902

9

21.0

3.5

294.15

0.00339963

2.5441

10

16.0

3.0

289.15

0.00345841

2.4771

 

The parameters for the linear regression of the graph log (p) vs. 1/T are presented in the following table:

Parameter

Value

Slope

-1090.744297

Intercept

6.254459611

Correlation coefficient r

-0.9932

Coefficient of determination r²

0.9865

 

Using the equation stated above, vapour pressures at ambient temperature were calculated as:

Vapour Pressure (20.0 °C): 342 Pa

Vapour Pressure (25.0 °C): 395 Pa

Conclusions:
The vapour pressure of the test item 1,3-Diiodopropane was calculated as 342 Pa at 20.0 °C and 395 Pa at 25.0 °C, based on results in the study.
Executive summary:

Using the static method according to OECD 104 resp. EU A.4, vapour pressures of 342 Pa at 20.0 °C and 395 Pa at 25.0 °C for 1,3-diiodopropane were determined.

These values were calculated from the regression of 10 individual measurements, which were performed in a temperature range of 16.0 – 55.0 °C.

The measured values for pressure p and temperature T were used to calculate pairs of log p and 1/T. These values were plotted; from the linear regression (Coefficient of determination r² = 0.9865), vapour pressures at ambient temperature were determined.

Description of key information

Using the static method according to OECD 104 resp. EU A.4, vapour pressures of 342 Pa at 20.0 °C and 395 Pa at 25.0 °C for 1,3-diiodopropane were determined.

These values were calculated from the regression of 10 individual measurements, which were performed in a temperature range of 16.0 – 55.0 °C.

The measured values for pressure p and temperature T were used to calculate pairs of log p and 1/T. These values were plotted; from the linear regression (Coefficient of determination r² = 0.9865), vapour pressures at ambient temperature were determined.

Key value for chemical safety assessment

Vapour pressure:
342 Pa
at the temperature of:
20 °C

Additional information