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Density

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Endpoint:
density
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Measurements were conducted with a method recommended in the current guidelines, and sounds of good scientific quality, however some informations are missing to allow full validation.
Reason / purpose:
reference to same study
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 109 (Density of Liquids and Solids)
Qualifier:
equivalent or similar to
Guideline:
EU Method A.3 (Relative Density)
Type of method:
oscillating densitimeter
Key result
Type:
density
Density:
1.383 g/cm³
Temp.:
25 °C

Density of selected water-TFEtOH mixtures at 25°C

wt.% Density (g/cm3)
0,00 0,997070
9,97 1,032140
20,02 1,068590
30,01 1,105920
40,01 1,144380
49,98 1,181910
60,02 1,220900
70,01 1,261100
80,04 1,302740
90,03 1,339310
100,0 1,382710

The publication also provides a table with 25 density results for 0-1 mole fraction water-TFEtOH mixtures at 25°C.

The results of the present work on TFEtOH alone is also compared with litterature data:

°C Density (g/cm3) Ref.
0,0 1,4106 Janz 1972, Riddick 1986
22,0 1,3736 Janz 1972, Riddick 1986
25,0 1,3826* Evans 1971
25,0 1,38271* this work

* TFEtOH is highly hygroscopic and changes in density are observed when the liquid is not properly stored.

Data from different sources indicate a significant scattering on density values. In particular, the density of freshly distilled TFEtOH and of TFEtOH-rich solutions decreases when the samples are exposed to air. For instance, the freshly distillled fluorinated alcohol has a density of about 1.3827 g/cm3 at 25°C, which reduces to 1.3737 in a week, when the sample is kept in open air. Such behavior implies a strong affinity of TFEtOH for water vapor.

Executive summary:

The publication describes experimental density measurements, with oscillating densitimeter, of aqueous solutions of 2,2,2-trifluoroethanol varying from 0 to 100 %. For the pure substance, the result was found to be 1.3827 g/cm3 at 25°C. It is also pointed out that 2,2,2-trifluoroethanol has affinity with water vapor, so that exposure to air leads to rapid decrease of the density.

Endpoint:
density
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 109 (Density of Liquids and Solids)
Qualifier:
equivalent or similar to
Guideline:
EU Method A.3 (Relative Density)
Type of method:
pycnometer method
Key result
Type:
density
Density:
1.383 g/cm³
Temp.:
298 K
Remarks on result:
other: (mole fraction = 1.0)

The densities of solutions in water are given in the following table:

Mole fraction Density (g/cm3)
0,0365 1,06117
0,0661 1,10279
0,130 1,16686
0,188 1,20925
0,271 1,25475
0,354 1,28551
0,519 1,32737
0,645 1,34837
0,773 1,36385
1,000 1,38335
Executive summary:

The densities of aqueous of solutions of 2,2,2-Trifluoroethanol, having a molar ratio ranging from 0.0365 to 1.0, were measured using a pycnometer method. At 25°C, the density of the pure alcohol was found to be 1.38335 g/cm3.

Description of key information

Experimental results: 1.3827 g/cm3 (Gente 2000), 1.3834 g/cm3 (Rochester 1974).

Key value for chemical safety assessment

Relative density at 20C:
1.383

Additional information

Two published experimental studies, conducted with oscillating densitimeter (1.3827 g/cm3) and pycnometer (1.3834 g/cm3), were considered reliable for the determination of the density.

Literature provides consistent data (1.362 to 1.39 g/cm3), except the Sax's handbook value, that was discarded, as considered inconsistent compared to the other results (1.288). Values from Baehr's publication were not taken into account as not suitable (pressure > ambient).

As the substance is known to absorb air moisture, the slightly higher mean of the two experimental results will be considered as the endpoint key value rather than the arithmetic mean of all retained values (1.381 g/cm3).