Utilizing Unexpected Results in Water Electrolysis to Engage Students in Scientific Inquiry

Water electrolysis, a well-known and simple experiment, confirms that a water molecule comprises hydrogen and oxygen atoms. In this experiment, hydroxide or hydrogen ions generated from each electrode were identified using an indicator based on the assumption that electrodes, electrolytes, and indicators do not participate in the water electrolysis reaction. However, KNO 3, which is considered as an electrolyte that is nonreactive during water electrolysis when considering the standard reduction potential, can affect electrolysis. Pencil graphite electrodes, which are commonly used in student experiments because of their low cost and easy availability, and indicators used to identify the products of water electrolysis can also influence this reaction. Therefore, students can observe various anomalies during the water electrolysis experiments. We have developed an experimental activity that allows students to observe anomalous phenomena in water electrolysis experiments. By performing this water electrolysis activity, students can participate in the process of scientific inquiry, create models, design their own research processes, conduct experiments, analyze and interpret data, and formulate evidence-based arguments based on the results of the proposed activity. By engaging in this activity, students can realize that water electrolysis is a complex process that is affected by a range of conditions.