If I Could I Wood … A
Destructive Distillation
How’s about a little distillation?
Distillation, process used to separate the substances composing a
mixture. It involves changes of phase only. There is no chemical change here!
The process was probably first used in the production of intoxicating
beverages. Today, refined methods of distillation are used in many industries,
including the alcohol and petroleum industries.
A simple
distillation apparatus consists essentially of three parts: a flask
equipped with a thermometer and with an outlet tube from which the vapor is
emitted; a condenser that consists of two tubes of different diameters placed
one within the other and so arranged that the smaller (in which the vapor is
condensed) is held in a stream of coolant in the larger; and a vessel in which
the condensed vapor is collected. The mixture of substances is placed in the
flask and heated. Ideally, the substance with the lowest boiling point
vaporizes first, the temperature remaining constant until that substance has
completely distilled. The vapor is led into the condenser where, on being
cooled, it reverts to the liquid (condenses) and runs off into a receiving
vessel. The product so obtained is known as the distillate. Those substances
having a higher boiling point remain in the flask and constitute the residue.
When
the substance with the lowest boiling point has been removed, the temperature
can be raised and the distillation process repeated with the substance having
the next lowest boiling point. The process of obtaining portions (or
fractions) in this way is one type of fractional
distillation. Fractional distillation is commonly used in refining
petroleum, some of the fractions thus obtained being gasoline, benzene,
kerosene, fuel oils, lubricating oils, and paraffin.
Another
form of distillation involves heating (out of free contact with air) such
substances as coal, oil and shale and collecting separately the portions
driven off; this is known as destructive
distillation. Coal, for example, yields coal gas, coal tar, ammonia, and
coke. Ammonia is also obtained by the destructive distillation of oil shale.
The Question! What wood happen
if we were to do a destructive
fractional distillation of wood???
?Gimme!! some hypotheses:
?Draw!! a picture of the distillation apparatus that you would use for
this lab. Be sure to label all parts.
Materials:
2
ring stands 3
burette clamps 1
Bunsen burner 3 test tubes
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1
duel glass-bend setup 1
rubber tube 1
600 mL beaker 1 500 mL Erlenmeyer flask
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1
bucket wood
splints 1
glass-bend-tube setup matches
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The Procedure!!
part 1:
pack a test tube with wood splints (broken in ˝)
set up distillation apparatus as demonstrated
heat splints strongly
light the gas from the exhaust port w/ a match ?observation notes:
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part 2: attach rubber tubing to exhaust port (as demonstrated)
collect gas using displacement method until flask is full
bring full flask to hood upside down *keep from flame*
disconnect rubber tubing from exhaust port
relight the gas at the exhaust port (keep burning 2-5 min) ?observation notes (esp. the distillate):
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part 3:
set up 2nd distillation apparatus as demonstrated
heat distillate liquid until approximately ˝ has boiled off
compare the liquid in the two test tubes
mix both liquids together ?observation notes:
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light one on fire ?observation notes:
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The Results!!! Answer the following in complete sentences on separate
paper.
1.
What happened when the test tube was heated initially?
2.
Did the gas burn? Why do you suppose that this happened?
3.
How much gas did you collect?
4.
Was this an effective means for gas collection? Why or why
not…
5.
How many liquids were collect in the initial distillation?
6.
What happened when you mixed the liquids together?
7.
Describe the wood splints after the distillation.
8.
Did they burn?
9.
Why do you suppose this happened?
10.
What is
wood anyway?
11.
What is
it made out of?
12.
Does
wood (any wood) burn?
13.
What is
the “combustion of wood” process? (you mat need to consult an outside source
here…)
14.
Can you
get the wood back by recombining all of the materials collected?
15.
Why or
why not?
16.
Were all
of the distillates that were collected there all of the time, or were they
formed by heating?
17.
What is
your evidence for your response?
18.
Is wood
a mixture? If so, what kind? Why would you say so?
19. Remember the candle trick from the first day of school??? What does this lab have to do with it?