用全程监测pH方法探究酸碱指示剂颜色变化及其选择

The Exploration of the pH Indicator Color Change and Its Choice in the Methods of Entire Monitoring pH

本实验依据人类对事物的认识规律,采用"全程监测pH"的方法,引导学生边实验边观察边总结边归纳。实验以甲基橙、溴甲酚绿-甲基红、甲基红、酚酞4种指示剂为例,监测4种指示剂在不同pH下的变色过程,观察酸式变色点、混合中间色、碱式变色点的pH、颜色和消耗的滴定剂体积。通过实验学会了指示剂终点颜色的确定方法,能准确把握各指示剂的终点颜色,并理解了指示剂的选择方法原则。

The experiment according to the law of human understanding of things, with the method of ＂the whole monitoring pH＂, guide students to experiment and observation summary and conclusion. Experiment with methyl orange, bromocresol green, methyl red and methyl red, phenolphthalein four indicator as an example, the four indicator monitoring in the process of color change under different pH, observe acid type mixed color changing point, demitint, alkali type color, color, and consumption of the pH value of the point of titrant volume. Learned indicator through the experiment, and a method for determining the finish color can accurately grasp the finish color of each indicator and understand the principles of the choice of indicator method.