The video below appeared as stimulation for both MYP4 and MYP5 tasks with the same name.  The exercise here, of course, include more questions/tasks.

In any case, the video demonstrates an explosive reaction between two gaseous elements. Mixtures of the two gases are contained in three different plastic bottles with a rubber bung at the mouth. The reaction is initiated by introducing a lit match next to a small hole on the side of the bottle covered with a small cello (scotch) tape.

Though all three contain mixtures of the same two gases, the reaction is a little different from one another in its vigor/explosiveness. Watch the video to see and hear the results.

Here are the questions:

  1. If you did not attempt the M4 version of this task, first identify gases in the plastic bottle. The gases are colorless and odorless.  (All you are being asked to do is use your knowledge of the periodic table and some basic properties about the elements on it.)
  2. List some observations about the canons which shows that the energy involved, the explosiveness of the reactions were different. (The final canon was shot outside as the loudness would have been a little too much in the laboratory. All three bottle were of the same capacity.)
  3. Explain why there was a difference in the loudness.
  4. Now that you know what the gases are and why their explosiveness varies, determine the theoretical ratio of the two gases in a 500-ml bottle that would produce the loudest bang.
  5. Look up the enthalpy of combustion of the relevant element (or the enthalpy of formation of the product) and determine the amount of energy the above mixture would generate.
  6. If you were to prepare a plastic bottle canon containing the volumetric ratio of the gases identified in 4 and set it off, would it generate the amount of energy calculated in 5? Why or why not?
  7. What would be a better composition to use in a 500-ml bottle to generate the loudest bang? Why?
  8. Design an investigation to investigate the relationship between the volumetric ratio of the gases and the loudness of the bang so as to identify the experimental ratio which produces the loudest bang. (As we don’t have readily available cylinders of the gases in the lab, you’ll have to describe how you will generate the gases and fill the bottles.)

Concept involved:

  • periodic table, reactive gases, physical properties, color, odor.
  • stoichiometry, stoichiometric ratio, mole ratio, volumetric ratio.
  • , theoretical ratio, experimental ratio, energetics, enthalpy of combustion, enthalpy of formation, energy change.

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