Good Morning :

1
Good Morning! ) Please hand in the lecture
problem on the desk in front BEFORE lecture
begins! You will not be allowed to hand in the
lecture problem once the answer has been given.
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Distillation Boiling Point
Next Week in Lab Chapter 5 Experiment

• Note Fill in the Common Shelf Chemical Data
  Table. Once complete,
• photocopy, and hand in with Ch 5 PreLab.
  Chemicals that appear on
• this table are not included on the regular
  chemical data tables.
• When using Aldrich, pick the chemical entry that
  does NOT have
• isotopic labeling, e.g, d, 15N, 13C. These are
  more expensive and will
• have different FWs. Aldrich will also tell you
  if a chemical is
• flammable, toxic or an irritant.
• This Week In Lab
• Ch 4 Recrystallization/Melting Point,
  Procedures 1, 2, and 4
• (Procedures 3 and 5 can be done next week)
• Hand in Ch 4 PreLab
• Quiz 1

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Distillation Boiling Point

• Distillation
• Purification technique
• Used to separate components of a liquid mixture
  or to purify an
• impure liquid
• Several basic types/variations
• Simple distillation
• Fractional distillation
• Simple, high vacuum distillation
• Steam distillation

• Boiling Point
• Physical property of a compound
• Used to identify an unknown

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The Distillation Experiment Ch 5

• A two-day lab
• Day One
• Based on your desk location, you will be doing
  one of the four following distillations
• Macroscale simple distillation (Procedure 1)
• Either a cyclohexane/toluene mixture OR an
  ethanol/water mixture (Fig. 5.3)
• Macroscale fractional distillation (Procedure 2)
• Either a cyclohexane/toluene mixture OR an
  ethanol/water mixture (Fig. 5.4)

You will share your data with some of your bench
mates then graph each set of data. You will then
assess and compare the effectiveness of simple
and fractional distillations.
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Simple vs. Fractional
Prediction Fractional distillation is a more
effective purification technique than simple
distillation. An example Excel graph with two
data sets superimposed
bp of pure B
A two- component mixture A B
Simple distillation
Temperature (C)
Fractional distillation
bp of pure A
Drops of Distillate
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Simple vs. Fractional

• Simple Distillation
• Used to separate mixture into pure components
• Works best if components boiling points differ
  by at least 75C
• Fractional Distillation
• To be used when components boiling points are
  closer together
• Unlike simple, uses a fractioning column this
  column may be packed with material so as to
  increase the surface area for heat exchange, thus
  increasing the number of theoretical plates.
• The more theoretical plates, the better the
  purification/separation.

Theoretical Plate one cycle of vaporization and
condensation Refer to Fig. 5.1
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The Distillation Experiment Ch 5
Day Two Procedure 3 A microscale
distillation of a 5050 unknown, two- component
mixture. Based on the observed boiling point
data, determine the identities of the two
components in your unknown mixture. Graph data
in Excel. Also, do solubility tests on each of
the purified liquids to confirm identities. Possi
ble unknowns acetone, methanol, hexane,
t-butanol, water, toluene, 1-butanol Refer to
Fig. 5.5 - Insulate your set-up with glass wool
and be sure to use the correct column (distilling
column) from your microscale kit!!!
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Distillation Natural Product Isolation
Steam distillation of citral from lemon grass
oil Citral (oil) comprised of

• Uses of citral
• Defense pheromone for ants
• In perfumes for lemon-like scent
• Precursor to vitamin A

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Next Week in Lab

• Chapter 5, Procedure 1 or 2
• Quiz 5 PreLab is due. Dont forget to include
  the Common Shelf
• Chemical Data Table!
• Quiz 2 on Chapter 5