Extraction of Pure Elements from Nature

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Extraction of Pure Elements from Nature

• Which elements are easy?

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Easy elements are gases that exist in the
elemental form

• N2, O2, noble gases
• Obtained by distillation of cooled, liquified
  air.

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Preview
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Extraction of Metals
All metals exist as cations in chemical compounds
in the crust. Key reducing the cations to the
neutral metal. Example Fe2O3 has Fe3 ions. To
obtain Fe metal, need to add 3 electrons to each
Fe3 ion.
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What well find.
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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)
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Consider the decomposition of Fe2O3
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Consider the decomposition of Fe2O3
C(s)
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5.6 CO2(g)
-393.5 213
-394.4
Reaction with C
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Consider the decomposition of HgO
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Aluminum Production