Intensive General Chemistry

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Intensive General Chemistry

• Chemical separations I

Isabelle Vu Trieu ilv2_at_columbia.edu http//ull
.chemistry.uakron.edu
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What is a distillation?

• This a separation technique for purifying a
  liquid.
• In this process, the liquid is heated to the
  boiling point and vaporized.
• That vapor is then cooled and recondensed in the
  liquid form

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Origin of distillation
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Partition
Partition constant K aA(phase 2)/ aA(phase 1)
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Ideal solutions

• Solutions are ideal when the intermolecular
  interactions among species are identical
• An ideal solution obeys Raoults law
• PA XA PAo

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Raoults Law applied to mixtures
Relative volatility ? or RV
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Relative Volatility ? or RV
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Phase diagram
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In the distillation process, the vapors get
enriched in the more volatile component
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In the distillation process, the vapors get
enriched in the more volatile component
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Fractional distillation numerous
evaporation-distillation stages
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Distillation columns
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Distillation set-up
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Introduction to chromatography

• Chromatography is a separation technique based on
  partition between a mobile phase and a stationary
  phase.
• Invented by a botanist (M.Tswett) at the
  beginning of the 20th century
• From greek chromacolor and grapheinwrite

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Introduction to chromatography
Mobile phase
Stationary phase
Partition constant K aA(stationary)/
aA(mobile)
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Column Elution
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Column Elution
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Thin Layer Chromatography (TLC)
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Pre-lab questions

• Find out the flash point and the auto-ignition
  temperature of cyclohexane and toluene.
• What is the meaning of these temperatures?
• In the distillation part, what is the role of the
  stainless steel sponge?