Oxidising and reducing agents
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The teaching part (1 min) is free to watch. A free account opens the whole lecture: 4 worked examples, 7 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- Who does the work?
- Oxidising agents
- Reducing agents
- The memory trick
Read the transcript of the teaching part
Last time
Before we start: last time, in Redox, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
Who does the work?
In every redox reaction one substance is oxidised and another is reduced. But there is a trick: the substance that causes the oxidation is called the oxidising agent. And the one that causes reduction is the reducing agent. Each agent does a job, and in doing it, changes itself.
Oxidising agents
An oxidising agent oxidises another substance, by taking electrons from it. So the oxidising agent itself gains electrons. It is reduced. Its oxidation number goes down.
Reducing agents
A reducing agent reduces another substance, by giving electrons to it. So the reducing agent itself loses electrons. It is oxidised. Its oxidation number goes up.
The memory trick
The agent always does the opposite to itself. The oxidising agent gets reduced. The reducing agent gets oxidised. So to find the agent, first find what is reduced, and then name the other reactant.
How often it comes up
How often Cambridge has asked each part, counted by ExamYard from every past paper in its question bank: Oxidising and reducing agents · Oxidising and reducing agents.
The whole chapter: Chemical Reactions, Chemical Reactions.
Chapter 6: Chemical reactions
- Collision theory and rate graphs 6 min
- Dynamic equilibrium, position of equilibrium and industry 6 min
- Oxidation numbers and redox 6 min
- Oxidising and reducing agents 6 min
Also for IGCSE Chemistry 0620
Which topics come up most in IGCSE Chemistry 0620 past papers, counted from every paper since 2004.