Abstract:

The classical basic chemistry experiment "determination of micro-quantitative fluorine in water with ion-selective electrode method" was improved to "determination of fluorine content in tea and tea water with ion-selective electrode method". The experimental contents for the "determination of fluorine in tap water" were extended to the "determination of fluorine in tea and tea water, fluorine leaching rate of tea leaves." The effects of tea : water ratio, temperature, brewing time, and tea powder size on the fluorine leaching rate of tea leaves were also investigated. The fluoride content in five kinds of representative tea samples showed that drinking dark tea caused the risk of excessive fluoride intake. In addition, the experiment was further expanded and extended to the ion selective electrode method and other detection methods of trace fluoride. The introduction of research content and grouping experiments was more beneficial to cultivate students' scientific research thinking and spirit of unity and cooperation. Exploratory and challenging experimental contents improved students' ability to innovate and solve practical problems. The infiltration of tea and general health knowledge in students' lives, enhanced their health consciousness. This experiment was rich in content, interesting, easy to operate and promote, and thus suitable for junior undergraduates.

Key words: Improvement of classical experiment, Ion-selective electrode method, Tea, Fluorine content, Innovative talent cultivation