Reactivity of Household Oxygen Bleaches: A Stepwise Laboratory Exercise in High School Chemistry Course

Abstract

This paper reports on a learning program designed for high school chemistry classes that involves laboratory exercises using household oxygen bleaches. In this program, students are taught the chemistry of oxygen bleaches through a stepwise inquiry using laboratory exercises organized with different pedagogical intents. Through comparative investigations of chemical properties of liquid and solid oxygen bleaches, students are introduced to sophisticated chemical concepts behind household oxygen bleaches and the dependence of their oxidizing activities on certain reaction conditions. This learning program also provides suitable opportunities at each investigative step for the introduction of mechanisms of reactions that involves H2O2. The students effectively use the attained chemical knowledge and concepts for the reasoning of observed phenomena in each investigative step and construct the basis toward subsequent inquiry steps. This learning program is concluded with a discussion by the students on the effective use of the chemistry of oxygen bleaches and a demonstration of Fenton's reaction using liquid oxygen bleach as a possible solution for current environmental issues regarding contaminated water. An outline of the learning program is described based on practice trials within high schools and an undergraduate introductory chemistry class taught at our university.