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The Pop Bottle Experiment

Keywords

hydrogen, oxygen, water, energy

Summary

A pop bottle is filled with a 1:2 mixture of oxygen and hydrogen. The Bunsen burner provides the initiation of the combustion reaction, and a loud pop is observed.

Hazards

  • It is important to use a thick walled vessel for this procedure. Use only the green "pop bottle" from the demonstration laboratory.
  • Hydrogen gas is very flammable.
  • Oxygen is an oxidizer.

Chemicals and Solutions

  • Hydrogen tank
  • Oxygen tank

Materials

  • Rubber hose
  • Trough
  • Coke bottle (Old glass, thick walled)
  • #2 solid rubber stopper
  • Bunsen burner
  • Matches
  • Heavy gloves and goggles
  • (2L beaker)

Procedure

  1. Before class, fill the coke bottle and trough with water. Displace 2/3 of the water with H and the remaining 1/3 of the bottle with O.
  2. In the classroom, set-up burner and matches in lecture room.
  3. To set off the pop bottle, wear goggles and gloves, uncork the bottle and bring the bottle opening horizontally to the burner. BOOM!!!

Hints: If preparing the demo in advance, cork bottle tightly with rubber stopper and invert the bottle in a beaker of water until classtime.

Discussion

\( \ce{ 2H2_{(g)} + O2_{(g)} -> 2H2O_{(g)} ~~~~ \Delta G^{{o}}_{Rxn} = -457.2KJ/Mol } \)

Water is very stable! Once heat provides the necessary activation energy, Ea , the reaction proceeds rapidly. The initial heat and the energy released by the reaction expand the gases greatly, creating an explosive force within the confined space of the bottle.

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