Abstract:

The physicochemical method is a classic experimental method in basic chemistry and also an important component of experimental training in undergraduate chemistry courses. However, existing measurement methods exhibit some drawbacks in terms of a lack of environmental protection of the experimental system, introduction of experimental errors, difficulty with controlling the operation steps, and a long experimental time. Based on green chemistry experiments and advanced, innovative, and challenging teaching requirements, the existing boiling point elevation method for measuring the molecular weight of compounds was explored. In the experiment, isopropanol instead of cyclohexane (acetone) was used as the solvent, benzoic acid instead of naphthalene was used as the solute, a water bath and electric heating rod were used for double heating, and a digital micrometer thermometer was affixed to the apparatus to improve the measurement accuracy. With these experimental improvements, the reagent was green, equipment was easy to operate, anti-interference ability of the device was strong, experimental reproducibility was good, and measurement error was reduced. Based on the foundation, the implementation of high-level, attach importance to challenges, the students' understanding of the number dependence of dilute solution is strengthened, and their practical and innovative thinking is cultivated.

Key words: Boiling point elevation method, Determination of molecular weight, Experimental improvement, Isopropanol, Benzoic acid