Understand the principles and applications of electrochemistry

Skill 11.1 Interpreting the behavior of common substances in terms of oxidation-reduction reactions 

Redox is shorthand for reduction and oxidation. Reduction is the gain of an electron by a molecule, atom, or ion. Oxidation is the loss of an electron. These two processes always occur together. Electrons lost by one substance are gained by another. In a redox process, the oxidation numbers of atoms are altered. Reduction decreases the oxidation number of an atom. Oxidation increases the oxidation number. 

The easiest redox processes to identify are those involving monatomic ions with altered charges. For example, the reaction 

However, many redox reactions involve the transfer of electrons from one molecular compound to another. For example, the reaction 

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