Hydrogen peroxide molecular formula and structure
Hydrogen peroxide is an important inorganic chemical having molecular formula H2O2. Thus hydrogen peroxide widely uses in textiles, paper, pump, lather, and oil industry in our everyday life.
Hydrogen peroxide forms a very interesting gauche structure. Therefore two O-H planes lie perpendicular to each other. But the structure of the solid slightly modified by hydrogen bonding.
The valence shell electron configuration of oxygen
Thus oxygen form O-O linkages by using the PZ orbitals of the two oxygen atom.
Preparation of hydrogen peroxide
H2O2 may be prepared in the laboratory by reacting dilute H2SO4 with crystalline barium peroxide.
BaO + H2SO4 → BaSO4 + H2O2
How to make hydrogen peroxide by electrolysis?
Hydrogen peroxide makes by anodic oxidation of 50% H2SO4 followed by careful vacuum distillation. In this process, H2S2O8 acid first formed which hydrolyzed to form H2SO5 and then to H2O2.
H2SO4 → H+ + HSO4–
2HSO4– → H2S2O8 + 2e
2H+ + 2e → H2
H2S2O8 + H2O → H2SO5 + H2SO4
H2SO5 + H2O → H2O2 + H2SO4
Physical properties of H2O2
Pure H2O2 is an extremely plate blue liquid, m.p -0.430C and b.p 1500C. The heat of formation of liquid H2O2 = -187 kJ mol-1 but it is thermodynamically unstable due to decomposition.
H2O2 (l) → H2O (l) + [O]
However, at the ordinary temperature, the decomposition is very slow but rapidly at a high temp. Thus it kept preferably in polythene containers which stabilize like urea or phosphoric acid.
Chemical properties of H2O2
The chemical solution of hydrogen peroxide can function as an acid, as an oxidant, and as a reductant.
Acid behavior of H2O2
It behaves like a weak dibasic acid but slightly stronger acid ten water.
H2O2 → H+ + HO2– pKa (200C) = 11.75
Oxidizing behavior of H2O2
Hydrogen peroxides behave as a strong oxidant in both acid and base solution. The potentials for the redox reaction
H2O2 + 2H+ + 2e → 2H2O E0 = 1.77 volt
HO2– +H2O + 2e → 3OH– E0 = 087 volt
The high potential shows that in an acid solution of hydrogen peroxide easily oxidizes iron (II) to iron(III), bromide to bromine, iodide to iodine.
2Fe+2 + H2O2 +2H+ → 2Fe+3 + 2H2O
2I– + H2O2 + 2H+ → I2 + 2H2O
Reducing the behavior of H2O2
In the presence of very strong oxidizing agents such as chlorine or permanganate or dichromate in acid solution, it oxidizes to form oxygen. In other words, it acts as a reducing agent.
Cl2 + H2O2 → 2HCl + O2
Hydrogen peroxide uses in everyday life
Hydrogen peroxide largely uses as a medicine or a bleaching agent in our everyday life.
- About 30% of peroxide used as a bleaching agent for textiles, paper, pump, later, oils, etc.
- A large quantity of about 33% uses in the manufacture of borax, epoxides, propylene oxide, and other chemicals.
- Hydrogen peroxide used in mild antiseptic to prevent the small cut, scapes, and buns on the skin. It may also use as a mouth rinse in medicine to the freshness of mouth.
- In environmental science, hydrogen peroxide uses in pollution control for the treatment of sewage cleanup and wastes.