Oxidation And

1
Oxidation And Reduction
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Oxidation

• Process in which atoms or ions attain a more
  oxidation state
• Ex.
• Na ? Na e
• Cl- ? Cl e
• Ca ? Ca2 e

3
Reduction

• Atoms or ions of elements attain a more negative
  oxidation state
• Ex.
• Cl e ? Cl-
• Mnemonic OIL RIG
• Oxidation involves loss, reduction involves gain

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Oxidation Number

• Uncombined elements have oxidation of 0
• Monoatomic ions have oxidation equal to their
  ion charge
• F is always 1 in a compound
• O is almost always 2 in a compound
• H is 1 in all compounds except those with metals
  (then its 1)
• More electronegative element is assigned a number
  equal to its ion charge
• Algebraic sum of oxidation numbers in a compound
  is always zero

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Practice

• Determine the oxidation numbers for each element
  in the compounds below
• NaCl
• H2SO4
• AgNO3
• CO2
• SF6
• NO3-

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Redox Reactions

• Redox reactions are among the most common of all
  chemical processes
• Combustion, synthesis, decomposition, and single
  replacements are all redox reactions

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Definition

• Reaction in which a change in oxidation number
  occurs
• Oxidation becomes more positive
• Reduced becomes more negative
• Oxidation and reduction always come in pairs
• Oxidizing Agent substance reduced
• Reducing Agent substance oxidized

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Example

• In the reactions below, identify what is
  oxidized, what is reduced, the oxidizing agent
  and the reducing agent
• 2PH3 4O2 ? P2O5 3H2O
• 2H2O Al MnO4- ? Al(OH)4- MnO2

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More Examples

• For each, write the reaction, then identify what
  is oxidized, what is reduced, the oxidizing agent
  and the reducing agent
• E\A5_T1.mov
• E\A10_T1.mov