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.




2 ring stands

3 burette clamps

1 Bunsen burner

3 test tubes


1 duel glass-bend setup

1 rubber tube

1 600 mL beaker

1 500 mL Erlenmeyer flask


1 bucket

wood splints

1 glass-bend-tube setup



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:




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):




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:




 Part 4: examine the wood splints in the test tube

          light one on fire

?observation notes:



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?