(a) How is `H_(2)O_(2)` prepared?
(b) Explain about the structure of `H_(2)O_(2)`.

Explanation

(a) Hydrogen peroxide can be made by adding a metal peroxide to dilute acid.
`BaO_(2(s))+H_(2)SO_(4(aq))toBaSO_(4(aq))+H_(2)O_(2(aq))`
(b) Structure of `H_(2)O_(2)`.

(i) `H_(2)O_(2)`has a non-polar structure. The molecular dimensions in the gas phase and solid phase differ as shown in the figure.
(ii) Both in gas phase and solid phase, the `H_(2)O_(2)`, molecule adopt a skew configuration due to repulsive interaction of the -OH bonds with lone pairs of electrons on each oxygen atom.
(iii) Indeed, it is the smallest molecule known to show hindrance rotation about a single bond. In solid phase, the dihedral angle is sensitive and hydrogen bonding decreasing from `115.5^(@)` in the gas phase to 90.2o, in the solid phase.
(iv) Structurally, `H_2O_2` is represented by the dihydroxyl formula in which the two O-H groups do not lie in the same plane. In the solid phase of molecule, the dihedral angle reduces to 90.2" due to hydrogen bonding and the `O - O - H` angle expands from `94.8^(@)` to `101.9^(@)`.
(v) One way of explaining the shape of hydrogen peroxide is that the hydrogen atoms would Tie on the pages of a partly opened book, and the oxygen atoms along the spin.