Redox chemistry

One of the Royal Society of Chemistry’s Developing Expertise in Teaching Chemistry courses covers the subject of redox chemistry and how teachers can understand the difficulties their students have with the topic. This article gives you a flavour of that course and introduces some of the strategies you can use to deal with students’ difficulties and misconceptions.

Most teachers introduce the concept of redox reactions when teaching the reactions of various elements with oxygen. This naturally leads to establishing a reactivity series of metals, which is extended by introducing the metals’ reaction with water and acid and adding transformations that are not easily demonstrated. Hydrogen and carbon find their place in this reactivity series as components of displacement reactions and teachers can use this opportunity to explain the extraction of metals from their ores. Students easily understand these concepts but start having problems when electron transfer is introduced.

Historically, the two types of static electricity were assigned the symbols + and –. When scientists discovered current electricity, they agreed on the convention of current flowing from + to –. Students have difficulty equating this with a flow of electrons in a wire in the opposite direction, or the flow of positive ions in a melt or solution in the same direction as the conventional current while negative ions flow in the opposite direction.

By demonstrating the ion movement under the influence of an applied current, teachers can address pupils’ problems.