How is ozone prepared from oxygen ? Explain its reaction with
KI

Explanation

Preparation of Ozone : When a slow dry stream of oxygen is passed through a silent electrical discharge, oxygen is converted to ozone. This product is called ozonised oxygen.
`3O_(2) rightarrow 2O_(3), triangle H^(@) (298K) = + 142 KJ "/" mol`
If high concentration of ozone `(gt 10%)` is required, a battery of ozonisers can be used. Pure ozone can be condensed in a vessel surrounded by liquid oxygen.
Iodide is oxidised to Iodine.
`2KI + H_(2) O + O_(3) rightarrow 2KOH + I_(2) + O_(2)`