Explain the physical and chemical properties of dioxygen.

Explanation

Physical properties : Dioxygen is a colourless and odourless gas.
The water solubility is `3.08 cm^3` per 100 `cm_3` water at 293 K which is just sufficient for the vital support of marine and aquatic life.
It has three stable isotopes : 160, 170 180.
It liquefies at 90 K and freezes at 55 K.
Molecular oxygen, (`O_(2)`) is paramagnetic due to presence of unpaired electrons in `pi^(*)` orbitals.
(B) Chemical properties :
(i) Reaction with metals : Dioxygen directly reacts with nearly all metals and except Au and Pt to form oxides.
For example :
`2Ca + O_(2) to 2CaO`
`4Al + 3O_(2) to 2Al_(2)O_(3)`
`4Fe + 3O_(2) to 2Fe_(2)O_(3)`
(ii) Reaction with non-metals
`C + O_(2) to CO_(2)`
`P_(4) + 5O_(2) to P_(4)O_(10)`
(iii) Reaction with compounds:
`2ZnS + 3O_(2) to 2ZnO + 2SO_(2)`
`CH_(4) + 2O_(2) to CO_(2) + 2H_(2)O`
Catalytic oxidation - `2SO_(2) + O_(2) overset(V_(2)O_(5)) to 2SO_(3)`
`4HCl + O_(2) overset(CuCl_(2))to 2Cl_(2) + 2H_(2)O`