A Method for Teaching How to Balance Redox Reactions by Building Up Molecules

Balakrishnan Viswanathan^1, and Mohamed Shajahan Gulam Razul¹

¹Department of Chemistry, St. Francis Xavier University, PO Box 5000, Antigonish, NS B2G 2W5, Canada

Cite this paper

Balakrishnan Viswanathan and Mohamed Shajahan Gulam Razul. A Method for Teaching How to Balance Redox Reactions by Building Up Molecules. World Journal of Chemical Education. 2020; 8(2):67-70. doi: 10.12691/WJCE-8-2-2

Abstract

The standard first-year program includes a section on the balancing of chemical reactions. Students find it difficult to understand this concept as it is increasingly presented as an algorithm or mathematical procedure. This submission outlines a method of teaching students how to balance redox reactions using known chemical principles: oxidation state (including the ionic approximation of molecules), conservation of number (conservation of mass and non-transmutability of chemical particles), and spectator ions. The method involves identification of the oxidation/reduction pairs and balancing the skeletal oxidation/reduction reactions (electron loss/gain) to enforce the link between change in oxidation state and transfer of electrons. The molecular species in the reaction are then built up by adding in other elements with their associated oxidation states, treating them as spectator ions. Equalising the number of electrons in the oxidation and reduction reactions leads to the balanced redox reaction. This method has been tested on a variety of reactions and examples of the three classes of redox reactions are presented. It is expected that students will be able to master the title concept due to the link to fundamental chemical concepts, further enhancing their understanding of the concepts involved.

Keywords

general chemistry, stoichiometry, oxidation state, balancing, redox reactions, algorithms

Copyright

This work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

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