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Melting point / freezing point

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Reference
Endpoint:
melting point/freezing point
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:
other: GB/T 510-1983 Petroleum products. Determination of solidification point.
Principles of method if other than guideline:
Step 1. Pour the sample into the test tube to the level mark,and install a thermometer into the test tube. Heat the tube vertically in a water bath to 50±1 ℃. Step 2. Take the tube out of the water bath, and fix it into a jacket with cork and clamp the jacket vertically in the air. Cool the sample at room temperature to 35±5 ℃. Immerse the test jar in a container filled with coolant and the immersing deepth should be no less than 70 mm.The initial temperature of collant should be about 7~8 ℃ lower than the expected solidification point, accurate to ±1 ℃. When the sample temperature equals the expected solidification point, lean the jacket to 45 ℃ and hold for 1 minute. Make sure the sample is below the coolant surface during the process. Take the jacket out of the coolant and wipe the outside surface with ethanol. Fix the jacket vertically and observe whether the sample surface will move or not. Step 3. If the sample surface moves, take the tube out of jacket and heat to 50±1 ℃ in the water bath again. Then repeat step 2 at a temperature 4 ℃ lower. Repeat again at a lower temperature until the sample surface stops moving. Step 4. If the sample surface stops moving, take the tube out of jacket and heat to 50±1 ℃ in the water bath again. Then repeat step 2 at a temperature 4 ℃higher or other higher temperature, until the sample surface moves again at given temperature. Step 5. After finding the solidification temperature range, repeat the test procedure at a temperature 2 ℃ lower than the moving temperature or 2 ℃ higher than the non-moving temperature. Until the sample surface stops moving at given temperature (T) and moves again at 2 ℃ higher, take T as the solidification point of the sample. Step 6. The test should be repeated. The initial test temperature this time should be 2 ℃higher than the achieved solidification point last time.
GLP compliance:
no
Other quality assurance:
ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
Type of method:
method to determine freezing temperature
Key result
Melting / freezing pt.:
ca. -6 °C
Atm. press.:
ca. 1 kPa
Conclusions:
The freezing point is -6 °C

Description of key information

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:
-6 °C

Additional information