ZIMSEC · Form 4
Chemistry
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- Electrolysis Electrolysis is the decomposition of an ionic compound, molten or in solution, by passing electricity through it.
- Energy changes and rates of reaction Particles must collide with enough energy (the activation energy). The rate increases with:
- Metals and their extraction K, Na, Ca, Mg, Al, (C), Zn, Fe, Pb, (H), Cu, Ag, Au. More reactive metals displace less reactive ones from solutions of their salts, e.g. Zn + CuSO₄ → ZnSO₄ + Cu.
- Non-metals, air and water About 78% nitrogen, 21% oxygen, 0.04% carbon dioxide, plus argon and water vapour. Pollutants: carbon monoxide (incomplete combustion, poisonous), sulfur dioxide (burning coal, acid rain), nitrogen oxides (car engines), particulates.
- Organic chemistry Organic compounds contain carbon. A homologous series has the same general formula, similar chemical properties and a gradual change in physical properties.