Question

(a) How is H₂O prepared? 

(b) Explain about the structure of H₂O₂ .

Answer 1

(a) Hydrogen peroxide can be made by adding a metal peroxide to dilute acid.

BaO_2(s) + H_(s)SO₄ → BaSO_4(s) + H₂O_2(aq)

(b) Structure of H₂O₂

(i). H₂O₂ 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 H₂O₂ 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 111.50 in the gas phase to 90.2°, in the solid phase.

(iv). Structurally, H₂O₂ 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 lie on the pages of a partly opened book, and the oxygen atoms along the spin.