Ozone - O3

What is Ozone?

Ozone is an allotropic molecular form of oxygen containing three atoms of oxygen (O3). Ozone O3 is generated through the passage of oxygen O2 through a high voltage potential resulting in the attachment and formation of a third oxygen atom. The molecular formula for ozone (O3) was established by Soret (1863) by taking the ratio of the change in volumes when O3/O2 mixtures were either heated or exposed to turpentine and cinnamon oil. The word ‘ozone’ comes from the Greek word ‘ozein’ which means ‘to smell’. This meaning comes from ozone at the ground level, which gives off a pungent, acrid odour.

Other names – Triatomic oxygen




2.14 kg/m³

Molecular Weight/ Molar Mass

48 g/mol

Boiling Point

-112 °C

Melting Point

-192.2 °C

Chemical Formula


Ozone Structure – O3

Ozone Structure

Physical Properties of Ozone – O3


Similar to chlorine


Pale blue gas

Covalently-Bonded Unit


Hydrogen Bond Acceptor





Soluble in water, CCl4, Sulfuric acid

Chemical Properties of Ozone – O3

  • Ozone dissolves in water resulting in the formation of hydrogen peroxide. The chemical equation is given below.
  • O3 + 3H2O → 3H2O2

  • Ozone reacts with lead sulfide resulting in the formation of lead sulfate. The chemical equation is given below.
  • 3PbS + 4O3 → 3PbSO4

Uses of Ozone – O3

  • Ozone used at water treatment plants without filtration systems.
  • Ozone may also be formed by commonly used equipment such as photocopiers, laser printers, and other electrical devices.
  • In medicine, by limiting the effects of bacteria, viruses, fungi, yeast, and protozoa, ozone therapy is used to disinfect and treat diseases.
  • Several ozone-depleting compounds possess properties that make them good refrigerants that is, they can efficiently transfer heat from one location to another.

Practise This Question

What would happen, if all the oxygen present in the environment is converted to ozone?