substance what happens role X loses electrons, oxidation number rises ? Y gains electrons, oxidation number falls ? The table lists two substances taking pa...
Question 1 Report
| substance | what happens | role |
|---|---|---|
| X | loses electrons, oxidation number rises | ? |
| Y | gains electrons, oxidation number falls | ? |
The table lists two substances taking part in the same redox reaction. Complete the table by choosing the correct roles for X and Y.
Answer Details
Read the two definitions in the table against OIL RIG. The substance X loses electrons and its oxidation number rises, so X is oxidised. The substance Y gains electrons and its oxidation number falls, so Y is reduced.
Now name the roles by what each does to its partner. X supplies the electrons that reduce Y, so X is the reducing agent. Y takes the electrons that oxidise X, so Y is the oxidising agent. The correct completion is therefore X as the reducing agent and Y as the oxidising agent.
Swapping them is the classic error, caused by naming the agent after what happens to it rather than what it does to the other substance. The two remaining choices break the reaction altogether: a redox reaction always needs one of each, since electrons lost by one species must be gained by another.
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