Cambridge IGCSE Chemistry · Syllabus 0620 · Chemical Reactions
Oxidising Agent
What is Oxidising Agent?
A substance that oxidises another substance and is itself reduced in the process. It takes electrons from the other species, or supplies oxygen to it, and its own oxidation number therefore decreases.
This definition is part of the Chemical Reactions chapter in Cambridge IGCSE Chemistry.
Common mistakes with Oxidising Agent
- 19. “The species oxidised is the oxidising agent.” Supplement 6.4.13 Why temptingThe two phrases share a word and differ by three letters. RepairThe species oxidised gave electrons away, causing reduction elsewhere, so it is the reducing agent. An oxidising agent is itself reduced. TransferIn \(\mathrm{2Mg + O_2 \rightarrow 2MgO}\), name both agents. Magnesium reducing; oxygen oxidising.
Examiner tips on Oxidising Agent
- Evidence first, name second. “Identify the oxidising agent” is asking for two things: which species it is, and how you know. Write the oxidation number change, or the electron transfer, and then name the agent. A bare name is an assertion; the evidence is what makes it an answer — and, since the inversion is so easy to get backwards, writing the evidence first is also the best way to catch your own error.