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Unformatted text preview: er of each underline d element in the compounds shown below: a) SO2 b) H3PO4 c) HC2H3O2 2 Chemistry 52 Chapter 17 REDOX REACTIONS
· Oxidationreduction (redox) is a chemical process in which the oxidation number of an element is changed.
· Oxidation occurs when the oxidat ion number of an element increases as a result of losing electrons. 0
o ss o f 1 +
Ag ¾l¾ ¾e¾ Ag ®
· Reduction occurs when the oxidat ion number of an element decreases as a result of gaining electrons. 2
Cu + ¾gain o¾ e¾ Cu ¾ f 2 ®
· In a redox reaction oxidation and reduction occur simultaneously, one cannot occur in the absence of the other. Examples: For each reaction below, determine the oxidized and reduced species, and the number of electrons transferred: 1. 2 Ca (s) + O2 (g) ¾¾ ® 2 CaO (s) 2. HF + KOH ¾¾ ® KF + H2O 3 Chemistry 52 Chapter 17 OXIDIZING AND REDUCING AGENTS
· Oxidizing agent: The substance that causes an increase in the oxidat ion state of another substance. The oxidizing agent is reduced in a redox reaction. 0
Cu + 2 Ag ¾¾ Cu + + 2 Ag ® · Reducing agent: The substance that causes a decrease in the oxidation state of another substance. The reducing agent is oxidized in a redox reaction. 0
Cu + 2 Ag ¾¾ Cu + + 2 Ag ® Examples: Ident ify the oxidizing and reducing agents in the reactions shown below: 1. Zn (s) + H2SO4 (aq) ¾¾ ZnSO4 (aq) + H2 (g) ®
React ion can be more clearly seen in the net ionic form: +
Zn (s) + 2 H (aq) ¾¾ Zn + (aq) + H2 (g) ® Oxidizing agent:_______________ Reducing agent:________________ 2. Ca (s) + H2O (l) ¾¾ Ca(OH)2 (aq) + H2 (g) ® Oxidizing agent:_______________ Reducing agent:________________ 4 Chemistry 52 Chapter 17 HALFREACTIONS
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