C401Ch18LN1 - Chapter 18: Electrochemistry Part 1...

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Chapter 18: Electrochemistry Part 1 Oxidation-Reduction Reactions Oxidation-Reduction rxns (called redox) are electron-transfer rxns. In redox rxns, the oxidation states of one or more substances changes. Many common reactions are examples of redox rxns: iron rusting in the presence of oxygen zinc (or many other metals) reacting with acid • combustion rxns batteries and electrolysis rxns Oxidation States Remember how to determine oxidation numbers for atoms? What are the oxidation states of all the elements in the following rxn? Zn(s) + HCl(aq) ± ZnCl 2 (aq) + H 2 (g) What elements are changing oxidation states in the above? If an element loses electrons (oxidation state increases), then it is being oxidized . What element is being oxidized in the above? If an element gains electrons (oxidation state decreases), then it is being reduced . What element is being reduced in the above? In any redox rxn, one substance is reduced while another is oxidized. Just to annoy and confuse you, the substance which is being reduced is called the oxidizing agent or oxidant , as it takes 1 or more electrons to the other substance. Likewise, the substance which is being oxidized is called the
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This note was uploaded on 06/25/2008 for the course CHEM 400-401 taught by Professor Dr.samples during the Fall '06 term at American River.

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C401Ch18LN1 - Chapter 18: Electrochemistry Part 1...

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