write 3 examples of Reduction reactions
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Explanation:
The Definition of Reduction in Chemistry
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Oxidation and reduction occur in batteries. Erik Dreyer / Getty Images
by
Anne Marie Helmenstine, Ph.D.
Updated July 04, 2018
Reduction involves a half-reaction in which a chemical species decreases its oxidation number, usually by gaining electrons. The other half of the reaction involves oxidation, in which electrons are lost. Together, reduction and oxidation form redox reactions (reduction-oxidation = redox). Reduction may be considered the opposite process of oxidation.
In some reactions, oxidation and reduction may be viewed in terms of oxygen transfer. Here, oxidation is the gain of oxygen, while reduction is the loss of oxygen.
An old, less-common definition of oxidation and reduction examines the reaction in terms of protons or hydrogen. Here, oxidation is the loss of hydrogen, while reduction is the gain of hydrogen.
The most accurate reduction definition involves electrons and oxidation number.
Examples of Reduction
The H+ ions, with an oxidation number of +1, are reduced to H2, with an oxidation number of 0, in the reaction:
Zn(s) + 2H+(aq) → Zn2+(aq) + H2(g)
Another simple example is the reaction between copper oxide and magnesium to yield copper and magnesium oxide:
CuO + Mg → Cu + MgO
Rusting of iron is a process that involves oxidation and reduction. Oxygen is reduced, while iron is oxidized. While it's easy to identify which species are oxidized and reduced using the "oxygen" definition of oxidation and reduction, it's harder to visualize electrons. One way to do this is to rewrite the reaction as an ionic equation. Copper(II) oxide and magnesium oxide are ionic compounds, while the metals are not:
Cu2+ + Mg → Cu + Mg2+