Save Baby Paul: Teacher's Notes

Activity: How Cotton Burns

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.

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Objectives

National Science Education Standards: Content Standards

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

Materials

Method

  1. Have the students place an untreated cotton ball on a noncombustible surface (in a hood if available).
  2. Have the students ignite the cotton ball. The students should monitor the amount of time that is required for the cotton ball to ignite (start burning).
  3. Have the students observe the combustion of the cotton ball after the ignition source (the lighter or Bunsen burner) is removed. Have the students describe their observations in writing, noting as many detailed changes as possible.
  4. Have the students prepare a treated cotton ball by dusting a cotton ball with baking soda. The experiment may be modified by having the students weigh the cotton ball before and after dusting with baking soda and then determining the amount of baking soda that has been applied.
  5. Have the students repeat the combustion test on the treated cotton ball.

Questions

  1. How is the ignition of the treated cotton ball different from the untreated cotton ball?
  2. How is the combustion of the treated cotton ball different from the untreated cotton ball?
  3. What property (or properties) of baking soda would explain these observations?
  4. Would you expect a cotton ball treated with flour to behave in the same manner as the cotton ball treated with baking soda?
  5. How might the surface area be important to ignition and combustion?

Extensions

  1. To examine the effect of surface area, the experiment can be repeated with cotton string and a piece of cotton fleece that have been dusted with baking soda.
  2. Are the changes observed due to the fact that the baking soda is a powder? Try treating a cotton ball by soaking it in a saturated solution of baking soda in water. Have the students weigh the cotton ball before and again after it's dry to determine how much baking soda was adsorbed. (Was the uptake of baking soda similar to that of the powder?)
  3. Do other powders behave the same way? Try treating a cotton ball with flour, baking powder, baby powder, powdered soap, etc.

CAUTION

DO NOT try any of the following: gasoline, fingernail polish remover, lighter fluid or any known flammable liquid or solid. These can produce a very flammable or even explosive cotton ball.


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