An improved apparatus for measuring freezing points has been developed. Compared to the traditional Beckmann freezing point instrument, the improved one overcame prior difficulties with solidification of liquid and made the solid-liquid equilibrium reversible with heat compensation from a heating tube. The reliability and accuracy were carefully examined by determining the freezing point of the solvent and solution, as well as calculating the molar mass of the solute. It was found that the molar mass was in good agreement with the literature data. Thus, this improved device can effectively and successfully be used in undergraduate physical chemistry laboratory courses.