Combustion of Cellulose: Teacher's Notes

Activity 1: Flammability of Cellulose and its Derivatives

Safety: First and Foremost

If you choose to do any of the testing as a demonstration or as hands-on activities, it's essential to follow all safety precautions to the utmost. Students may need to be reminded that burns are painful and can be disfiguring, and trying any of these experiments (especially the cellulose nitrate, even as commercial flash paper sold in magic stores) on a larger scale can be fatal. It is our hope that in providing video footage of the more dangerous demonstrations, the need for individuals to do these in person will be nil, and thus students will be able to see the chemistry and learn from it without any risk whatsoever.

DISCLAIMER:
We offer this site as an educational tool. WE ARE NOT RESPONSIBLE FOR ANY INJURY OR DAMAGE CAUSED TO ANY PERSON, DIRECTLY OR INDIRECTLY, RELATING TO ANY OF THE DEMOS OR EXPERIMENTS LISTED AT THIS SITE. YOU ARE WHOLLY RESPONSIBLE FOR YOUR SAFETY.

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Objectives

National Science Education Standards

This activity fulfills the following within the Content Standards: 9-12

Materials

Method

  1. Have the students place the cellulose sample on a nonflammable surface (in a hood if available).
  2. Have the students ignite the sample. After the sample has begun to burn, have the students remove the ignition source.
  3. Have the students place the cellulose acetate sample on a nonflammable surface (in a hood if available).
  4. Have the students ignite the sample. After the sample has begun to burn, have the students remove the ignition source.
  5. Have the students place the cellulose nitrate sample (smaller than the size of a small cotton ball) on a nonflammable surface (in a hood if available).
  6. Have the students ignite the sample. Use Extreme Caution! The sample will almost instantaneously ignite and burn completely within a second or two.

Questions

  1. Which sample burns the fastest? Why do you think this is the case?
  2. Which sample do you think releases the most heat? Why?
  3. Other than the speed of combustion, what differences did you observe?

Notes on The Igniter

Additional Safety Considerations

Never ignite anything in a sealed or closed container. You've probably noticed that some of the video demos were done underneath a 1-liter beaker. The only advantage to using a beaker is to be able to videotape, frame-by-frame, a flame in an atmosphere that is more quickly depleted of oxygen and more readily shows the combustion products. Please use our videos to show these effects, as the safety hazards far outweigh any observations that might take place outside the video. Specific hazards that we observed with the nitrocellulose were: 1) flames shot out from under the lip of the beaker, resulting in a singed experimenter, and 2) a few samples unpredictably did not ignite, but filled the beaker with copious amounts of toxic, flammable gases (including the red-brown NO2). Please do not put yourself and your students at risk, and conduct all experiments in open, still air, and NOT in an enclosed container.

Demonstration References

Synthesis of Cellulose Nitrate
Chemical Demonstrations: A Handbook for Teachers of Chemistry, Vol. 1; Shakhashiri, B.Z., Ed.; The University of Wisconsin Press; Madison, 1983; p. 43.


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