How is ozone prepared ? How does it react with the following ?
KI

Explanation

Preparation of Ozone :
When a show dry steam of oxgen is passed through a silent electrical discharge, oxygen is converted to ozone . This product is called ozonised oxygen
` 3O_(2) to 2O_(3), Delta H^(@) (298K) = + 142 ` kJ / mol
If high concentration of ozone `( gt 10%)` is required , a battery of ozonisers can used. Pure ozone can be condensed in a vessel surrounded by liquid oxygen
Properties
a) Pbs is oxidised to `PbSO_(4)`
`PbS(s) + 4O_(3) ( g) to PbSO_(4) + 4O_(2)`
b) ` I_(2)` is liberated. `I^(-)` is oxidised to `I_(2)`
` 2KI_((aq)) + H_(2) O (l) + O_(3) (g) to 2 KOH(aq) I_(2) (s) + O_(2) (g)`
c) `H_(2)` O formed sticks to the glass surface and mercury loses its meniscus due to dissolution of `Hg_(2)` O in Hg. this is called tailing of /Mercury
d) Silver metal is blackened . This is due to oxidation of the metal first to its oxide and subsequent reduction of the metal
` 2 Ag + O_(3) to Ag_(2) O + O_(2)` (oxidation)
` Ag_(2) O + O_(3) to 2 Ag + 2O_(2)` (reduction )