Oxidation and reduction as the gain and loss of oxygen, hydrogen and electrons. The rules for oxidation numbers, oxidising and reducing agents, and the kinds of redox reaction, including disproportionation.
3 lessons, about 1 h 15 min3 simulations10 problems3 practice questionsPython in every lesson
Created by StemPy LabOxidation and reduction began as the gain and loss of oxygen and hydrogen. A better idea is electron transfer: oxidation is the loss of electrons and reduction is the gain, and the two always happen together. A reducing agent gives electrons and an oxidising agent takes them. Zinc in copper(II) sulfate shows one metal winning the competition for electrons.
The oxidation number is the charge an atom would have if the bonding electrons went to the more electronegative atom. A short list of rules gives it, and the numbers for a compound or an ion add up to its charge. A rise in oxidation number is oxidation and a fall is reduction. An element in its highest state can only oxidise, and in its lowest state can only reduce.
Redox reactions come in five kinds. In combination and decomposition, elements are joined or set free. In displacement, a more active element takes the place of a less active one. In disproportionation one element goes both up and down, and in comproportionation two states of an element meet in one. Oxidation numbers are a useful tool, but they have limits.
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