How will you concentrate `H_(2)O_(2)` ? Show difference between structures of `H_(2)O_(2)` and `H_(2)O` by drawing their spatial structures . Also mention three important uses of `H_(2)O_(2)`.

Explanation

(i) Idustrially,`H_(2)O_(2)` is prepare by the auto-oxidation of 2-alklanthraquninols
2-ethylanthraquinol `underset(H_(2)//Pd)overset(O_(2)//("air"))hArr H_(2)O_(2)+` Oxidised product
In this case 1% `H_(2)O_(2)` is formed . It is extracated with water and concetrated to `~ 30%` (by mass) by distillation under reduced pressure.
It can be further concentrated to `~ 85%` by careful distillation under low pressure. The remaining water can be frozen out to obtain pure `H_(2)O_(2)`.
(ii) `H_(2)O_(2)` has a non-planer structure.
The molecular dimension in the gas phase and solid phase are shown below

(a) `H_(2)O_(2)` structure in gas phase, dihedral angle is `111.5^(@)`.
(b) `H_(2)O_(2)` structure in gas phase at 110 K, dihedral angle is `90.2^(@)`
In the gas phase, `H_(2)O` is a bent molecule with a bond angle of `104.5^(@)` and O-H bond length of 97.5 pm as shown below

(a) The bent structure of water, (b) The water molecule as a dipole and (c) The orbital overlop picture in water molecule.
(iii) Following are three important uses of `H_(2)O_(2)`
(a) In dialy life, it is used as a hair bleach and as a mild disinfectant . As an antisptic it is sold in the market as perhydrol.
(b) It is used in the synthesis of hydroqunce, tartaric acid and certain food products and pharmacetuicals (cephaloporin) etc.
(c) It is employed in the industries as a bleaching agent for textiles, paper pulp, leather, olis, fats etc.