Water and Wastewater Terms Beginning R

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redox reaction (REE-docks)

A two-part reaction between two ions involving a transfer of electrons from one ion to the other. Oxidation is the loss of electrons by one ion, and reduction is the acceptance of electrons by the other ion. Reduction refers to the lowering of the oxidation state/oxidation number of the ion accepting the electrons. In a redox reaction, the ion that gives up the electrons (that is oxidized) is called the reductant because it causes a reduction in the oxidation state or number of the ion that accepts the transferred electrons. The ion that receives the electrons (that is reduced) is called the oxidant because it causes oxidation of the other ion. Oxidation and reduction always occur simultaneously.