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Ozone is toxic


  • tesla coil clamped to ringstand
  • 4 Liter erlenmeyer flask
  • orange peel
  • watch glass or rubber stopper


  1. Place a small amount of water in the bottom of the flask.
  2. Secure the tesla coil to a ring stand and lower the tip of the tesla coil into the flask. The tesla coil should be placed so that any ozone that is generated is trapped inside the flask.
  3. Turn on the tesla coil for a couple of minutes.
  4. Remove the tesla coil and drop a fresh piece of orange peel in.
  5. Cover the flask. The ozone formed will attack the orange peel and a cloud of smog will be seen.


In this demonstration the ozone is prepared by subjecting molecular oxygen to an electrical discharge.

\( \ce{ 3O2 -> 2O3 ~~~~ \Delta G^{{o}} = 326.8 kJ } \)

Ozone attacks C=C bonds. C=C bonds are present in rubber and in limonene, (CH₁₆) a naturally ocurring monoterpene found in orange peel. Terpenes can be viewed as being built from two or more five carbon units known as isoprene units. Isoprene is 2-methyl-1,3-butadiene. In limonene, the isoprene units are arranged to form a 6 membered ring with branching off the ring. When ozone attacks the C=C bond ozone is inserted into the molecule forming an ozonide. The ozonide decomposes to form aldehydes and ketones.