Lightstick Kinetics

This experiment determines the energy of activation of the luminescent reaction in a lightstick by measuring the light intensity relative to temperature using Vernier light and temperature sensors, a Texas Instruments CBL interface, and a TI-82/83 graphing calculator. The light intensity and temperature are measured simultaneously with the light sensor in direct contact with the reaction test tube and the temperature sensor inserted directly in the reaction mixture. The test tube and sensors are supported in an easily manufactured wooden block. The data are stored in the calculator and the data analysis and graphing are completed on the calculator. The data can also be transferred to a computer for analysis and printing of the graphs. This procedure generates a high level of student interest and students develop an understanding of the relationship between temperature and the rate of reaction. The 10-min data collection time allows the experiment to fit high school class periods and several trials can be performed on the same sample. The experiment incorporates the use of technology, graphing, and data analysis. The graphical presentation of the relationship between light intensity and temperature may be sufficient for an introductory laboratory, while reserving the data analysis for an intermediate or advanced course. The directions can be easily modified to use computers and other graphing calculator probe systems.