Magnesium bis(dihydrogenorthophosphate)

Density

Link to relevant study record(s)

Reference

Endpoint:

relative density

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 109 (Density of Liquids and Solids)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.3 (Relative Density)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: 10 July 2012, Date of signature: 7 September 2012

Type of method:

pycnometer method

Remarks:

referred to as a 'gas comparison pyconometer' in the study report.

Type:

density

Density:

2 450 kg/m³

Temp.:

21.6 °C

Remarks on result:

other: Temperature: 21.6 ± 0.5 °C

Type:

relative density

Density:

2.45

Temp.:

21.6

Remarks on result:

other: 21.6 ± 0.5 °C

Calibration

The pressure readings and the calculated volume for the reference and sample cells are shown in the following table:

 

Table 1.

 

Determination	P1	P2	P3	P4	Reference Cell Volume (cm^3)	Sample Cell Volume (cm^3)
1	17.075	6.453	17.019	8.413	90.768	149.409
2	17.018	6.440	17.021	8.424	90.929	149.356
3	17.028	6.444	17.025	8.427	90.907	149.310

 

Sample

The pressure readings, calculated volumes and density values obtained for the test item are shown in the following table:

 

Table 2.

 

Determination	Test	P1	P2	Volume (cm^3)	Density (kg/m^3)	Mean Density (kg/m^3)
1	A	17.032	6.650	7.495	2.54 x 10^3	2.47 x 10^3
	B	17.011	6.651	7.817	2.44 x 10^3
	C	17.014	6.653	7.846	2.43 x 10^3
2	A	17.014	6.649	7.706	2.46 x 10^3	2.43 x 10^3
	B	17.074	6.677	7.865	2.41 x 10^3
	C	17.028	6.660	7.899	2.40 x 10^3

 

Temperature: 21.6 ± 0.5 ºC

Mean density: 2.45 x 103 kg/m3

Relative density: 2.45

Although testing would be preferable at 20 °C, the absence of methods of temperature control for the relevant apparatus meant this was not possible. However, as the EC A3 method guideline requires that the determination of density of solids is to be performed “at room temperature” and with the negligible influence of temperature on the density of solids, this was considered not to affect the validity of the result.

The mass density of a material varies with temperature and pressure and this variance is typically negligible for solids. Increasing the temperature of a substance may decrease its density by increasing the volume of that substance. Typical thermal expansion coefficients of solids are in the order of 10−5 °C−1, and the volumetric expansion of stainless steel (used as calibration spheres) at 20 °C is approximately 5.2 x 10-5 °C−1. Thus, a change in temperature of several degrees will have no significant effect on the volume and hence the density of a solid substance.

Thus, although relative density is defined using the density at 20 °C it is considered that the effect of temperature within normal laboratory conditions will not have a significant impact on either the determined density or calculated relative density.

Conclusions:

The density of the test item has been determined to be 2.45 x 103 kg/m3 at 21.6 ± 0.5 °C, relative density 2.45.

Description of key information

One key study exists. This study (Tarran D, 2012) was conclusive, done to a valid guideline (OECD 109) and the study was conducted under GLP conditions. It is therefore scientifically justified for use as a key study under Regulation (EC) No. 1907/2006 (REACH).

Key value for chemical safety assessment

Relative density at 20C:

2.45

Additional information

The density of the test item has been determined to be 2.45 x 103 kg/m³ at 21.6 ± 0.5 °C, relative density 2.45.