Detecting Color Change with an Arduino-Based Sensor System: The Iodine Clock Experiment

Abstract In chemistry laboratories, microcontroller boards can be used to reduce observer-dependent variability in student measurements. This technical report describes a low-cost Arduino-based sensor design that automatically detects the moment of color change in the iodine clock experiment, digitally records the reaction time, and emits an audible alert. The activity was implemented with 19 preservice chemistry teachers organized into four groups; one five-member group used the Arduino-based system, and interviews were conducted with these five participants to collect their views on its possible benefits for chemistry laboratory applications. Compared with traditional stopwatch-based timing, the Arduino-based system generally produced a narrower range and lower observed variability across repeated measurements, particularly under conditions with longer reaction times. In addition, participants in the Arduino group suggested that the design may offer accessibility-related benefits, as its audible feedback and sensor-based end point detection could reduce reliance on visual color judgment in laboratory activities.