Melting point / Boiling point
The melting point is defined as the temperature at which the phase transition from the solid to the liquid state at atmospheric pressure takes place.
The boiling point of a liquid is defined as the temperature (in K) at which the vapour pressure equals the standard atmospheric pressure 101.325 kPa.
Both the two properties are measured by Differential Scanning Calorimetry (DSC).
In both cases samples of the test substance and of a reference material are subjected to the same controlled temperature programme. The difference in energy input necessary to maintain identical temperatures between the substance and the reference material is recorded. When the sample undergoes a phase transition, the corresponding change of enthalpy gives a departure from the base line of the heat flow record.