What is Ozone

Ozone Molecule for Water Treatment
Discovered by Christian Friedrich Schonbein in 1840, Ozone is triatomic oxygen with the chemical formula O3. It derives its name from the Greek word ozein or ogeiv, “to smell or smell.”
Ozone gas is light blue at room temperature and has a characteristic pungent odor. Physical property data is provided in the table below:


Molecular Weight 48 g/mole
Density Relative to Air 1.66
Specific Weight at 0 degree C & 760 mm Hg 2.143 kg/m3
Heat of Formation 34.5 kcal/mole
Boiling Point -112 degrees C (dark blue liquid)
Melting Point -193 degrees C (dark red or blue solid)
At standard temperature and pressure ozone is a blue gas. Ozone forms a dark blue liquid below -112 °C and a dark blue solid below -193 °C. Ozone is a powerful oxidizing agent, and is unstable, decaying to ordinary oxygen through the reaction: 2O3 → 3O2.

Typical Ozone Lifetime as a Function of Temperature

Gaseous Dissolved in Water (pH 7)
Half Life Time Temperature Half Life Time Temperature
3 months -50 C 30 minutes 15 C
18 days -35 C 20 minutes 20 C
8 days -25 C 15 minutes 25 C
3 days 20 C 12 minutes 30 C
1.5 hours 120 C 8 minutes 35 C
1.5 seconds 250 C

Values based on thermal decomposition only, does not consider chemical reactions, wall and catalytic effects.

Approximate Solubility of Ozone in Water
As a Function of Temperature and Ozone Gas Concentration


Temperature (Degrees C) mg/l 100% Ozone in Gas mg/l 2.5 wt % Ozone in Gas mg/l 5.0 wt. % Ozone in Gas mg/l 10 wt. % Ozone in Gas
0 1090 27.5 54.5 109
10 780 19.5 39 78
20 570 14.25 28.5 57
30 400 10 20 40
40 270 6.75 13.5 27
50 190 4.75 9.5 19
60 140 3.5 7.0 14