← Oxidation-reduction processes
“An OX and a RED CAT”. Oxidation happens at the anode; reduction at the cathode.
“The agent does the opposite”. The oxidant is itself reduced; the reductant is itself oxidised. (The agent gives its name away to the other guy.)
3 Oxidation numbers & the language
Oxidation number rules (apply in order)
- Uncombined element = 0 (e.g. O₂, Na, Cl₂).
- Monatomic ion = its charge (Na⁺ = +1, S²⁻ = −2).
- H = +1 (except −1 in metal hydrides); O = −2 (except −1 in peroxides, +2 in OF₂).
- Sum of oxidation numbers = 0 for a neutral compound, = charge for an ion.
Mnemonics: redox in three lines
“OIL RIG”, Oxidation Is Loss, Reduction Is Gain (of electrons).“An OX and a RED CAT”. Oxidation happens at the anode; reduction at the cathode.
“The agent does the opposite”. The oxidant is itself reduced; the reductant is itself oxidised. (The agent gives its name away to the other guy.)
OIL RIG & the agents
- Oxidation Is Loss of electrons (oxidation number increases).
- Reduction Is Gain of electrons (oxidation number decreases).
- The oxidant (oxidising agent) is reduced, it takes electrons.
- The reductant (reducing agent) is oxidised, it gives electrons.