Oxidation-Reduction Reactions Ch 19 p. 591 Name the five reaction types you already know. Synthesis, decomposition, combustion , single-replacement, double-replacement. Now investigate a special characteristic Transfer of electrons from one atom to another. Oxidation-Reduction Reactions Ch 19 p. 591

Oxidation-Reduction Reactions Ch 19 p. 591

Oxidation-Reduction Reactions Ch 19 p. 591 Rules for assigning oxidation# in a chemical reaction Atoms of pure substances have oxidations of zero. Ex. Au, Fe, Ag, O2 2. Florine in compounds always -1 3. Oxygen almost always has -2 in compounds except when it is in a peroxide H2O2, when the oxygen oxidation number is -1. 4. Hydrogen has an oxidation number of +1 in all compounds containing elements that are more-electronegative than it; it has an ox# of -1 in compounds with metals.

5. In polyatomics the sum of oxidation# is equal to charge of ion. Ex. Nitrate (NO3) -1 Nitrite (NO2) -1 Sulfate (SO4) -2 Phosphate (PO4) -3 In neutral compounds the sum of ox# equal zero Ex. NaCl K2S H2O Element on right stays normal Oxidation number …/esselman

1. UF6 8. HNO3 2. H2SO4 9. P4O10 3. ClO3- 10. HClO3 4. HCl 11. N2O5 5. CF4 12. GeCl2 6. PCl3 7. SO2

Identifying Oxidation & Reduction Reacton “Moving electrons from one to another” “The element changes oxidation number” A substance that loses an e- becomes more positive so it is oxidized ( rusting….batteries….combustion…..electroplating A substance that gains an e- becomes more negative so it is reduced OIL RIG

OIL Oxidized Is Lost electron RIG Reduced Is Gained electron “You cannot have one without the other” For short, sometimes Chemist refer to these reactions as a “ redox reaction “.

Identifying reduction/ oxidation equations 1. assign all Oxidation numbers 2. did any numbers change 3. IF YES then Redox will have both oil/rig Practice sheet 19.2 ….p595…#2, #3.

Identify Reduction/Oxidation Equations 1. H2 + Cl2 2HCl 2. NaOH + HCl NaCl + H20 3. 8HNO3 + H2S 8NO2 + 4H20 + H2SO4 4. KNO3 2KNO2 + O2

H2 + CuO Cu + H2O CH4 + 2O2 CO2 + 2H2O 2Al + 3CuCl2 2AlCl3 + 3Cu 8. 2HgO 2Hg + O2

SnCl4 + 2FeCl2 2FeCl3 + SnCl2 2NH4Cl +Ca(OH)2 2NH3 + 2H2O + CaCl2 11. 2HNO3 +3H2S 2NO + 4H2O + 3S

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