Chemistry Teach Yourself Series - Topic 4 - Redox - Chemistry Teach Yourself Series Topic 4 Redox Author Pat OShea A Flinders Street Melbourne VIC 3000

Chemistry Teach Yourself Series - Topic 4 - Redox -...

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© TSSM 2010 Page 1 of 15 Chemistry Teach Yourself Series Topic 4: Redox Author: Pat O’Shea A: Level 14, 474 Flinders Street Melbourne VIC 3000 T: 1300 134 518 W: tssm.com.au E: [email protected]
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© TSSM 2010 Page 2 of 15 Contents What are they? ............................................................................................................................................... 3 Half equations ................................................................................................................................................ 4 Oxidation number .......................................................................................................................................... 5 Writing more complex half equations ........................................................................................................... 8 Will a reaction occur? .................................................................................................................................... 9 Half cells ...................................................................................................................................................... 10 Galvanic cells ............................................................................................................................................... 11 Solutions to questions .................................................................................................................................. 13
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© TSSM 2010 Page 3 of 15 Redox reactions What are they? Unit 2 Chemistry There are several categories of chemical reactions i.e. hydrochloric acid reacts vigorously with sodium hydroxide. HCl(aq) + NaOH(aq) Æ NaCl(aq) + H 2 O(l) H + This is referred to as an ACID-BASE reaction. Characteristic – proton (H + ) is transferred. Precipitation reaction – characteristic; a precipitate forms when two soluble ionic solutions are mixed. Redox reactions are another category of reaction. Characteristic – electrons transferred from one reactant to another. Example 1 Mg(s) + S(s) Æ MgS(s) 2e - Mg 2+ S 2- During this reaction, each magnesium atom donates 2 electrons to each sulfur atom. Redox : Involves electron transfer. One substance must donate electrons and one substance must accept electrons One substance donates electrons ; this is defined as oxidation One substance gains electrons ; this is defined as reduction . Oxidation loss of electrons ( electrons on right hand side of half equation) increase in oxidation number gain of oxygen loss of hydrogen Reduction gain of electrons ( electrons on left hand side of half equation) decrease in oxidation number loss of oxygen gain of hydrogen
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© TSSM 2010 Page 4 of 15 Ag(s)
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© TSSM 2010 Page 5 of 15 Ag(s)
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