Cobalt trihydroxide

Melting point / freezing point

Link to relevant study record(s)

Reference

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-07-29 to 2010-08-13

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

Deviations:

no

GLP compliance:

no

Type of method:

thermal analysis

Remarks:

differntial scanning calorimetry (DSC)

Atm. press.:

1 013 mBar

Decomposition:

ambiguous

Sublimation:

no

Remarks on result:

other: Decomposition to CoO(OH) at a temperature range (75-180°C) and further to Co2O3 (over 200°C), no melting point could be observed / no atmospheric pressure was stated, 1013mbar were assumed

Thermal stability:

The DSC-measurement up to 400 °C in a closed glass crucible with the test item showed undefined curve progression over the complete course of the measurement.

DSC:

The first measurement up to 200 °C in aluminium crucible (measured at 1011 hPa) with a hole showed an endothermic effect in the temperature range 75 -180°C.

An optical inspection of the test item showed that the test item was a powder after the measurement.

The second and third measurement up to 350°C and 600°C, respectively, in an aluminium crucible (measured at 1008 and 1012 hPa, respectively) with a hole showed two endothermic effects in the temperature range 80 -170°C and 250 -315°C.

An optical inspection of the test item showed that the test item was a powder after the measurement. It was assumed that the optical change of the test substance from pasty solid to a powder occurred due to loose of water and therefore it could be assumed that the test item transforms to CoO(OH) (temperature range 75 -180°C) and further to Co₂O₃ (over 200°C).

Conclusions:

The test item undergoes decomposition to CoO(OH) (temperature range 75-180°C) and further to Co2O3 (over 200°C). Hence, no melting point could be observed for cobalt trihydroxide.

Description of key information

Cobalt trihydroxide undergoes transformation to CoO(OH) (temperature range 75-180°C) and further to Co2O3 (over 200°C). Hence, no melting point could be observed for cobalt trihydroxide.

Additional information

The melting point of the test substance was determined according to OECD guideline 102 with the differential scanning calorimetry method (DSC). The test item was heated up from ambient to the final temperature (200 °C, 350 °C and 600 °C, respectively) at a constant heating rate (10 K/min) in a defined atmosphere (nitrogen). The quantity of heat absorbed or released was measured and recorded. Aluminium crucibles with a small hole were used as containers for the test item and as empty reference crucible.

A measurement in a capillary tube in a metal block was not possible due to the physical appearance of the test item (black paste).

The result of the optical inspection showed that cobalt trihydroxide decomposes to CoO(OH) (temperature range 75 -180°C) and further to Co2O3 (over 200°C).