HYDROGEN PEROXIDE - (7722-84-1)

Introduction

Name: hydrogen peroxide
* IUPAC
CAS Number: 7722-84-1
Chemical Formula: H2O2
Molar Mass: 34.01468 g
Mass Percent: H 5.9264 %; O 94.073 % 

Classification

• inorganic

Uses/Function

• "The chief practical use of hydrogen peroxide is for bleaching delicate materials, such as silk, wood, feathers, and ivory, which would be injured by more intensely active agents. It is also used as an antiseptic, but its most interesting use today is as an oxidant (a source of oxygen - an oxidizer or oxidizing agent) for the combustion of fuels in rocket propulsion." 1

• "Its use for bleaching hair is well known, but it is also important as a bleaching agent for textiles and for wood pulp and waste paper in paper making." 2

• "When a 3% solution of H2O2 is poured on a skin wound to cleanse it, the solution fizzes violently. An enzyme, or biological catalyst (called catalase) present in tissue and blood, decomposes the hydrogen peroxide and produces bubbles of oxygen. The natural function of this enzyme is to prevent the accumulation of hydrogen peroxide in the body, since such a build-up of H2O2 could damage tissue. Hydrogen peroxide is formed naturally in the body during oxidation reactions involving oxygen, O2.

In most of its reactions, hydrogen peroxide acts as an oxidizing agent, giving water as the reduction product...The oxidizing ability of hydrogen peroxide accounts for its use in the restoration of old paintings. The lead paint used in these paintings darkens in time as a result of the formation of black lead sulfide from small amounts of H2S in air. Hydrogen peroxide converts PbS to PbSO4, which is white. The bombardier beetle has a fascinating defense mechanism based on the oxidation of an organic compound with hydrogen peroxide. Within the beetle is a sac containing a mixture of the compound (hydroquinone) and hydrogen peroxide. An enzyme initiates the reaction, which is so exothermic that it causes the liquid to boil. The boiling liquid is then expelled at the beetle's enemies.

Hydrogen peroxide can also behave as a reducing agent in the presence of strong oxidizing agents, yielding oxygen and water. Potassium permanganate, KMnO4, is one of these oxidizing agents.

Hydrogen peroxide...is used as an antiseptic and hair bleach. However, its most important use is as a commercial bleach of textiles and paper pulp. Hydrogen peroxide is also increasingly used in treating waste water before it is discharged to natural bodies of water. It oxidizes certain pollutants to relatively harmless substances (for example, hydrogen sulfide is oxidized to sulfate ion)." 3

Physical Properties

Melting Point:*
-0.43°C 4 = 272.72 K = 31.226°F
Boiling Point:*
150.2°C 4 = 423.35 K = 302.36°F

* - 1 atm pressure

Bonding

Bonding: polar covalent
Ionic Character: 37.58 %

Thermochemistry

ΔHf° (ℓ): -44.88 kcal/mol 5 = -187.78 kJ/mol
ΔHf° (g): -32.53 kcal/mol 5 = -136.11 kJ/mol
S° (ℓ): 26.2 cal/(mol•K) 6 = 109.62 J/(mol•K)
S° (g): 55.66 cal/(mol•K) 6 = 232.88 J/(mol•K)
ΔGf° (ℓ): -28.78 kcal/mol 7 = -120.42 kJ/mol
ΔGf° (g): -25.21 kcal/mol 7 = -105.48 kJ/mol

Reactions

For More Information

Sources

(1) - Brownlee, Raymond B., Fuller, Robert W., and Whitsit, Jesse E. Elements of Chemistry; Allyn and Bacon: Boston, Massachusetts, 1959; p 29.
(2) - Gillespie, Ronald J., Eaton, Donald R., Humphreys, David A., and Robinson, Edward A. Atoms, Molecules, and Reactions; Prentice-Hall: Englewood Cliffs, NJ, 1994; p 591.
(3) - Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; pp 535-537.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2003; p 4-61.
(5) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(6) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(7) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(8) - T < 830.884955752212