34 . Ozone : Preparation :
i . It is prepared by passing silent electric discharge through pure and dry oxygen 10 – 15 % oxygen is converted to ozone .
3 O2 ( g ) → 2 O3 ( g ); H = + 142 kJ mol −1
Structure of Ozone : Ozone has angular structure . Both O = O bonds are of equal bond length due to resonance .
35 . Sulphur : Sulphur exhibits allotropy :
a . Yellow Rhombic ( α - sulphur ): b . Monoclinic ( β- sulphur ):
α − Sulphur YZZZZZZZZZX 369K β − Sulphur
At 369 K both forms are stable . It is called transition temperature .
Both of them have S8 molecules . The ring is puckered and has a crown shape .
Another allotrope of sulphur – cyclo S6 ring adopts a chair form .
S2 is formed at high temperature ( ∼ 1000 K ). It is paramagnetic because of 2 unpaired electrons present in anti bonding π * orbitals
like O2