Hydrogen Peroxide(H2O2) Properties (25 Facts You Should Know)

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Hydrogen peroxide is an unstable compound that decomposes in presence of light and heat. Let us explore the physical and chemical properties of hydrogen peroxide.

Hydrogen peroxide is a reactive oxygen species and becomes miscible in water. It is also soluble in ether. It is stored in a dark bottle (to get rid of light) with a stabilizer in a weakly acidic solution. The mixture of hydrogen peroxide and water behaves as a eutectic mixture showing a freezing point below 560 C.

Let us focus on the IUPAC name, reactions, polarity, magnetic behavior, melting, and boiling point of H2O2 briefly in this article.

Hydrogen Peroxide IUPAC Name

The IUPAC (International Union of Pure and Applied Chemistry) name of hydrogen peroxide is hydrogen peroxide itself.

Hydrogen Peroxide Chemical Formula

Hydrogen peroxide has the chemical formula H2O2.

Hydrogen Peroxide CAS Number

H2O2 has the CAS registry number 7722-84-1.

Hydrogen Peroxide Chem Spider ID

H2O2 has the ChemSpider (ChemSpider is a free chemical structure database) ID 763.

Hydrogen Peroxide Chemical Classification

  • H2O2 can be chemically classified as an inorganic liquid compound.
  • H2O2 can be chemically classified as a weakly acidic compound.
  • H2O2 can be chemically classified as a covalent compound.
  • H2O2 can be chemically classified as a reactive oxygen species and catalase.

Hydrogen Peroxide Molar Mass

The molar mass of H2O2 is 34.0147 g. This value of the molar mass is obtained from the summation of the molar mass of 2 oxygen atoms and 2 hydrogen atoms which are 15.999 g/mole (molar mass of one oxygen atom) and 1.00784 g/mole (molar mass of 1 H atom) respectively.

Hydrogen Peroxide Color

Pure H2O2 is pale blue. But it appears as a colorless liquid.

Hydrogen Peroxide Viscosity

H2O2 has a viscosity of 1.245 centipoises at 200 F and 1 atm. It has a slightly higher viscosity than water (the viscosity of water is 1 centipoise).

Hydrogen Peroxide Molar Density

The molar density of H2O2 is 0.0326 mol/cm3 because it has a density of 1.11 g/cm3 (200 C, 30% w/w solution) and a molar mass of 34.0147 g/mol.

Hydrogen Peroxide Melting Point

H2O2 has a melting point of -0.430 C or -31.230 F.

Hydrogen Peroxide Boiling Point

The boiling point of H2O2 is 150.20 C or 302.40 F.

Hydrogen Peroxide state at Room Temperature

At room temperature, H2O2 appears as a colorless liquid compound because there is a strong intermolecular hydrogen bonding present between the H2O2 molecules.

Hydrogen Peroxide Ionic/Covalent Bond

H2O2 is a covalent molecule. There are three covalent bonds present in the structure of H2O2. There is also one O-O bond and two O-H bonds having the length of 147.4 pm and 95.0 pm respectively present in H2O2 and the dihedral angle of this compound is 1110.

hydrogen peroxide properties
Covalent Bonds in H2O2

Hydrogen Peroxide Electron Configurations

Electron configuration defines the distribution of the electrons in different energy levels, known as electronic orbitals. Let us see the electron configuration of H2O2 in detail.

H2O2 has the electron configuration of [He] 2s2 2p4 for oxygen and 1s1 for hydrogen atom.

Hydrogen Peroxide Oxidation State

The oxidation state of H2O2 is 0 because it is a neutral compound. 2 oxygen atoms are in O22- and each of the 2 hydrogen atoms is in a +1 (H+) oxidation state.

Hydrogen Peroxide Acidity/Alkaline

H2O2 is an acidic liquid compound that forms hydroperoxide and peroxide salts. It is a weak acid with an acid dissociation constant (Ka) of 10-11.6 or pka = 11.6. H2O2 = 2H+ + O22-.

Is Hydrogen Peroxide odorless?

H2O2 is not an odorless compound and has a slightly sharp odor at low concentrations.

Is Hydrogen Peroxide paramagnetic?

Paramagnetism arises due to the presence of unpaired electrons which are attracted by the weak magnetic field. Let us check the magnetism of H2O2.

H2O2 is not a paramagnetic compound because there are no unpaired electrons present in H2O2. It is diamagnetic because each of the two oxygen atoms is sp3 hybridized and all the electrons of oxygen as well as the two hydrogen atoms are paired up in those four sp3 hybrid orbitals.

Hydrogen Peroxide Hydrates

H2O2 can form intermolecular hydrogen bonding with other H2O2 molecules. It acts as both the hydrogen bond donor and acceptor and appears as a liquid substance. It accepts hydrogen bonds through its two oxygen and donates through hydrogen atoms.

Hydrogen Peroxide Crystal Structure

The colorless crystal of H2O2 has a tetragonal structure with the space group of D44 -P4121. There are four molecules per unit cell. The lattice parameters a and c are 4.06 A0 and 8.00 A0.

Hydrogen peroxide Polarity and Conductivity

  • H2O2 is a polar molecule with a dipole moment of 2.26 D. This polarity arises due to the presence of the two polar O-H bonds. The bond moment of the two O-H bonds cannot be canceled by each other due to having a bent shape and a 1090-1110 dihedral angle.
  • H2O2 is a very weak electrolyte with low electrical conductivity power. It has a specific conductance value of 1.5×10-6. It also acts as a very good ionizing solvent.

Hydrogen Peroxide Reaction with Acid

H2O2 reacts with acetic acid (CH3COOH) and hydrochloric acid (HCl) to form peracetic acid and hypochlorous acid respectively.

  • CH3COOH + H2O2 = CH3COOOH + H2O
  • HCl + H2O2 = HOCl + H2O

Hydrogen Peroxide Reaction with Base

H2O2 reacts with the strong base, sodium hydroxide (NaOH) and forms sodium peroxide and water.

NaOH + H2O2 = Na2O2 + H2O

Hydrogen Peroxide Reaction with Metal

  • H2O2 undergoes a decomposition reaction in presence of finely divided metals to liberate gaseous oxygen.
  • 2H2O2 + Metal = 2H2O + O2.
  • Iron and H2O2 can oxidize a wide range of substrates. This reaction is known as the Fenton reaction.
  • Fe2+ + H2O2 + = Fe3+ + OH˙ (hydroxyl radical) + OH– (hydroxyl ion).

Hydrogen Peroxide Reaction with Oxide

H2O2 reacts with silver oxide and manganese dioxide and liberates oxygen.

  • H2O2 + Ag2O = 2Ag + O2 +H2O
  • H2O2 + MnO2 +2H+ = Mn2+ + O2 + 2H2O

Conclusion

Hydrogen peroxide is used as a good oxidizing agent, bleaching agent, and antiseptic (dilute solution of H2O2) also. It is a very unstable intermediate formed in the human body that can cause the oxidation of protein, lipid membrane, and DNA due to the formation of peroxide ions.