Oxidation and reduction reactions are the basis of understanding huge swathes of chemistry – from metal extraction (there’s a nice video of the microscale reduction of copper oxide here) to the chemistry of the halogens, from basic electrochemistry to fuel cells.
What is a redox reaction?
Reactions in which both oxidation and reduction occur are called redox reactions.
Discover the many definitions of oxidation and reduction, as well as figuring out the oxidising and reducing agent in a chemical reaction.
Rules for assigning oxidation states
We assign an oxidation state to each element in each reactant and product, and then we determine whether that element has been oxidised or reduced depending on how the oxidation state changes over the the course of the reaction.
Using oxidation states to write a half equation
Often writing a half equation to show reduction or oxidation is straight forward – all we need to do is work out whether electrons have been gained or lost by looking at the charges on the ions …
Writing balanced redox equations
Given two half equations, we need to be able to write a fully balanced redox equation both under acidic and alkaline conditions, using changes in oxidation state to guide us.
Redox titration exam question practice
Redox titration questions are very popular on exam papers. They are usually set in an unfamiliar context and may require you to work through a number of steps back through an experiment to get to the answer.
The key is, as always, to work logically from what you know. Annotate your working as you go so that you don’t lose your way.