1. Extraction of Pure Elements from Nature Which elements are easy?

2. Easy elements are gases that exist in the elemental form N 2, O 2, noble gases Obtained by distillation of cooled, liquified air.

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4. Extraction of Metals All metals exist as cations in chemical compounds in the crust. Key: reducing the cations to the neutral metal. Example: Fe 2 O 3 has Fe 3+ ions. To obtain Fe metal, need to add 3 electrons to each Fe 3+ ion.

5. What we’ll find.

6. Review of Thermodynamic Control of Reactions Enthalpy:  H depends on bond strength reactions favored by negative  H (which is forming stronger bonds) Entropy:  S depends on randomness (disorder) reactions favored by positive  S (increasing disorder, particularly formation of gases)

7. Consider the decomposition of Fe 2 O 3 Decomposition Reaction: 2 Fe 2 O 3 (s)  4 Fe(s) + 3 O 2 (g)  H o =  S o =  G o = Temperature where  G o is negative?

8. Consider the reaction of Fe 2 O 3 with C Reaction with C: 2 Fe 2 O 3 (s) + 3 C(s)  4 Fe(s) + 3 CO 2 (g) C(s) 0 5.6 CO2(g) -393.5 213 -394.4  H o =  S o =  G o = Temperature where  G o is negative?

9. Consider the decomposition of HgO 2 HgO(s)  2 Hg(l) + O 2 (g)

12. Aluminum Production 2 Al 2 O 3 (dissolved) + C(s)  4 Al(l) + 3 CO 2 (g)

13. Aluminum Production 2 Al 2 O 3 (dissolved) + C(s)  4 Al(l) + 3 CO 2 (g) Why use carbon instead of just a metal electrode?  G o 2 Al 2 O 3 (s)  4 Al(s) + 3 O 2 (g) = + 3164 kJ/mol E o =  G o 2 Al 2 O 3 (s) + 3 C(s)  4 Al(s) + 3 CO 2 (g) = + 1981 kJ/mol E o =

17. Gold! 4 Au(s) + 8 NaCN(aq) + O 2 (g) + 2 H 2 O(l)  4 NaAu(CN) 2 (aq) + 4 NaOH(aq)

18. Photography Chemistry Exposure: AgX  Ag(s) + X(s)

19. Photography Chemistry Developing: AgX(s) + e -  Ag(s) + X - (s) HQ  Q + 2 H + + 2e -

20. Photography Chemistry Fixing: AgX(s) + 2 Na 2 S 2 O 3 (aq)  Na 3 [Ag(S 2 O 3 ) 2 ](aq) + X - (aq)

23. Photography Chemistry