AP Chemistry / Unit 4: Chemical Reactions
4.9 Oxidation-Reduction (Redox) Reactions
Notes
- Oxidation: loss of electrons (oxidation number rises). Reduction: gain (it falls).
- The reducing agent is oxidized; the oxidizing agent is reduced.
- Oxidation numbers: elements are 0; O is usually −2; H is usually +1.
Practice
In $Zn+Cu^{2+}\to Zn^{2+}+Cu$, what is oxidized?
Zn loses electrons.
Oxidation number of S in $\mathrm{SO_4^{2-}}$:
$S+4(-2)=-2$.
The oxidizing agent:
It takes electrons.
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