Unformatted text preview: edox reactions can be separated into two halfreactions: oxidat ion and reduction.
· In an oxidation halfreact ion the electrons are lost, and therefore represented as product: 0
Cu (s) ® Cu + (aq) + 2 e- oxidation halfreaction · In a reduction halfreaction the electrons are gained, and therefore represented as reactant: +
Ag (aq) + e- ® Ag (s) reduction halfreaction · When two halfreact ions are added together, the number of electrons must be equalized in order to cancel oneanother. +
2 (Ag + e- ® Ag) reduction halfreaction +
2 Ag + 2 e- ® 2 Ag reduction halfreaction · The sum o f the two halfreact ions would then equal the overall react ion. 0
Cu ® Cu + + 2 e- oxidation halfreaction +
2 Ag + 2 e- ® 2 Ag reduction halfreaction 0
Cu + 2 Ag + 2 e- ® Cu + + 2 Ag + 2 e- 0
Cu + 2 Ag ® Cu + + 2 Ag 5 Overall reaction Chemistry 52 Chapter 17 Examples: 1. Write oxidat ion and reduction halfreact ions the following reaction: Mg (s) + Br2 (l) ® MgBr2 (s) Oxidat ion halfreact ion: Reduction halfreaction: 2. Write oxidat ion and reduction halfreact ions for the fo llowing react ion: Cl2 (g) + 2 NaBr (l) ® Br2 (l) + 2 NaCl (aq) Oxidat ion halfreact ion: Reduction halfreaction: 6 Chemistry 52 Chapter 17 ACTIVITY SERIES OF METALS
· Activity series is a list ing of metallic elements in descending order of reactivit y. Hydrogen is also included in the series since it behaves similar to metals.
· Act ivit y series tables are available in textbooks and other sources.
· Elements listed higher will displace any elements listed below them. For example Na will displace any elements listed below it from one of its compounds. 2 Na (s) + MgCl2 (aq) ® 2 NaCl (aq) + Mg (s) Na (s) + AgCl (aq) ® NaCl (aq) + Ag (s)
· Elements listed lower will no...
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