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Physical & Chemical properties

Melting point / freezing point

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Description of key information

The melting point of cesium hydroxide monohydrate was determined to be 204 °C at 1013.25 hPa.

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:
204 °C

Additional information

The determination of the melting point was performed according to EU Method A.1 and OECD Guideline 102 by applying the differential scanning calorimetry (DSC). Since the results from the DSC method could not be unambiguously interpreted as melting, supplemental measurements were performed with the capillary tube method with photocell detection. After a preliminary test for the determination of the starting temperature, 3 capillaries were prepared and measured with a heating rate of 0.2 K/min. The following results were obtained: 202.5 °C / 206.0 °C / 204.7 °C Since the reproducibility of the first test was not very good, the test was repeated with a higher heating rate of 1.0 K/min, yielding following results: 205.3 °C / 204.3 °C / 203.1 °C. The mean of all six measurements was calculated to 204°C, which is in agreement with the peak maximum temperature of the DSC measurement. Therefore, the melting point of cesium hydroxide monohydrate was determined to be 204 °C at 1013.25 hPa.