United States Pharmacopoeia freezing point
The freezing point is the temperature at which the liquid and solid solvents are in equilibrium, so that their vapor pressures are equal. When a nonvolatile solute is added to a volatile liquid solvent, the vapor pressure of the solution will be lower than that of the pure solvent. As a result, the solid will reach equilibrium with the solution at a lower temperature than the pure solvent. The explanation of the vapor pressure is equivalent to the argument based on the chemical potential, because the chemical potential of the vapor is pairwise related to the pressure. All colligative properties and this is due to the decrease in the chemical potential of the solvent in the presence of the solute. This reduction is an entropy effect. The greater randomness of the solution (as compared to pure solvents) is the opposite of freezing, so that a wider range of lower temperatures must be reached before an equilibrium between the liquid and solid phases can be achieved. To help identify the substance and determine its purity. Can be based on ST203B automatic freezing point tester and ST203C automatic drug freezing point tester in accordance with USP40 (United States Pharmacopoeia version 40) USP40 41 42 43 651 freezing point determination.
For example, the freezing point of pegylated acetic acid phenol, o-chlorophenol, chlorophenol, stearic acid, magnesium stearate, dibutyl hydroxytoluene, bisphenol A, etc.