Titration End Point in Determination Experiment of Edible Alkali
LIU Xiao-Geng1, LIU Qin1, REN Sai-Jia1, LIU Wen1, LU Jia-Jun1, ZHANG Xiao-Yun1, CUI Ying1, QIN Fu-Yi1, GAO Ran2
1. College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing 210023, China; 2. High School Affiliated To Nanjing Normal University, Nanjing 210003, China
Abstract Composition analysis and content determination of edible alkali is an important experiment which has the developing potential in the chemical experiment, but after designing the comprehensive design of open experiment we met a lot of interesting issues. How to make sure of the end point of phenolphthalein in the double indicator titration is one of the typical problems. Through asking question, making a thorough analysis and discussing the experimental study and theoretical analysis on phenolphthalein end point problem, we finally draw the conclusion that:at room temperature, NaHCO3 solution is completely spontaneously decomposed into Na2CO3, CO2, H2O and CO2 will automatically escape,and if we store it for a long time, the red end point will gradually increase. It shows that the choice of such experiments as the comprehensive and the opening experiments is very suitable for top undergraduates in analytical chemistry.
LIU Xiao-Geng, LIU Qin, REN Sai-Jia, LIU Wen, LU Jia-Jun, ZHANG Xiao-Yun, CUI Ying, QIN Fu-Yi, GAO Ran. Titration End Point in Determination Experiment of Edible Alkali[J]. , 2018, 39(6): 78-81.