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Redox!

Redox!. My favorite reaction. 2Na (s) + Cl 2(g) ->2NaCl (s) electron is transferred This is called oxidation-reduction or redox. Redox. Involves most rxns for energy production photosynthesis, combustion, breakdown of sugars, fats, proteins. Oxidation States.

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Redox!

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  1. Redox!

  2. My favorite reaction... • 2Na(s) + Cl2(g)->2NaCl(s) • electron is transferred • This is called oxidation-reduction or redox

  3. Redox • Involves most rxns for energy production • photosynthesis, combustion, breakdown of sugars, fats, proteins

  4. Oxidation States • A way to keep track of electrons in redox rxns • Oxidation states of covalent cmpds- arbitrarily assigned to certain atoms

  5. Rules- Oxidation States • Oxidation state of an atom in an element is zero.

  6. Element Examples... • Na(s), O2(g), O3(g), Fe(s), Hg(l) all have an oxidation state of 0

  7. Monatomic Ions • Oxidation state of monatomic ion is the same as its charge

  8. Monatomic Ion Ex • Oxidation state of: • Na+ = +1 • Cl- = -1 • Ca2+ = +2

  9. Fluorine • In its compounds, fluorine always has an oxidation state of -1.

  10. Oxygen • Assigned oxidation state of -2 in its covalent compounds. • CO, CO2, SO2, SO3

  11. Hydrogen Rules • In covalent compounds with nonmetals, H is assigned an oxidation state of +1.

  12. Hydrogen examples • HCl, NH3, H2O, CH4 • all have hydrogen at +1 oxidation state

  13. Sum of the states • Sum of the oxidation states must be 0 for neutral compounds or the charge of the ion for an ion

  14. Examples • Sum of states in CO32- • -2 • Sum of states in NH4+ • +1

  15. Let’s Try It! • CO2 • SF6 • NO3- • K2CrO4

  16. Redox Rxns • Some rxns are characterized by literal e- transfer • 2Na(s) + Cl2(s)->2NaCl(s)

  17. Less obvious redox • CH4(g) + 2O2(g) -->CO2(g) +H2O(g) • Assign oxidation states

  18. A closer look • Oxidation is an increase in oxidation state (a loss of electrons)

  19. A closer look • Reduction is a decrease in oxidation state (a gain of electrons)

  20. In the reaction... • 2Na(s) + Cl2(s)->2NaCl(s) • sodium is oxidized • chlorine is reduced

  21. However... • Chlorine is the oxidizing agent (e- acceptor) • sodium is the reducing agent (e- donor)

  22. In the other rxn... • C is oxidized (lost e-) • O is reduced (gained e- • CH4 is reducing agent • O2 is oxidizing agent

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