Chemical Properties of Ozone – O3

Ozone is a pale blue gas occurring naturally in small amounts in the stratosphere of Earth. The ozone layer is responsible for absorbing ultraviolet radiation, thereby protecting the surface of Earth and its living organisms from severe damage. The light blue ozone gas is explosive and toxic even at low concentrations. It is possible for many people to sense ozone at concentrations as low as 0.1 ppm in the air, which is similar to the odour of chlorine.

Photochemical reactions between hydrocarbons and nitrogen oxides in the lower atmosphere sometimes produce strong ozone concentrations. This can cause a burning sensation in the eyes and mucous membranes.

More about Ozone

In the aftermath of a thunderstorm or while near electrical equipment, the air takes on an unmistakable odour due to ozone, a triatomic oxygen allotrope. It was in 1785 that the odour of ozone near electrical equipment was first noticed, and it wasn’t until 1872 that the exact chemical composition of ozone was discovered.

In 1865, ozone’s structure was figured out. Later, it was found that the molecule has a bent structure and is somewhat paramagnetic.

As it cools to cryogenic temperatures, ozone solidifies, turning into a dark blue liquid and then a violet-black solid. High temperatures, physical stress or rapid warming to the boiling point will cause concentrated gas and liquid ozone to spontaneously decompose because ozone is incompatible with more common di-oxygen. Thus, it is used only in small quantities for commercial purposes.

Ozone is a powerful oxidant (much more potent than dioxygen), so it has various industrial and consumer uses. Because of its strong oxidizing potential, ozone can damage animal mucous and respiratory tissues as well as plant tissues when present in concentrations greater than 0.1 ppm. 

Physical Properties of Ozone

1.  An inert non-polar solvent such as carbon tetrachloride or fluorocarbons can be used to make a blue solution of ozone, which is a colourless pale blue gas. 

2. A dark blue liquid is formed at a temperature of 161K.

3.  Allowing this liquid to reach its boiling point could be risky as the concentrated form of gaseous or liquid ozone has the potential to explode.

4. It forms a violet-black liquid at temperatures below 80 degrees Celsius.

5. The smell of ozone is similar to that of chlorine bleach and thus makes it easily detectable in the atmosphere.

6. Exposure to ozone may cause chest pain, burning of eyes, headaches and throat irritation.

7. Even low concentrations of ozone in the atmosphere may have severe damaging effects on plants and animals.

8. The paramagnetic property of ozone is weak.

Chemical Properties of Ozone

Atomic Structure of Ozone

Microwave spectroscopy tests show that ozone is a bent water-symmetry molecule. O-O-O makes an angle of 116.78°. The central atom sp2 hybridize with only one pair. Ozone has a polar structure. The ozone molecule is a resonance hybrid of two structures, one of which has a single bond and the other has a double bond. Isoelectronic characteristics of ozone are identical to those of nitrite anions.

Structure of Ozone

The Process of Making Ozone

Electric discharges are used to make ozone in a laboratory by flowing through dry oxygen. There are some oxygen molecules that dissociate when an electric current is put through them, resulting in the formation of O3 and O2 from the mixture of these two elements.

Ozone Reactions

When it comes to oxidizing power, only O2 can compete with ozone. It is also unstable at high concentrations and degrades to ordinary oxygen. Weather conditions such as temperature, humidity, and airflow influence the half-life of a substance. The pace of this reaction increases as the temperature rises. At ozone concentrations of 10% or more, a spark can induce ozone deflagration. Oxygen can be converted to ozone in an electrochemical cell’s anode. Small volumes of ozone can be generated for scientific purposes by using this method.

Metals, with the exception of gold, platinum and iridium, are oxidized to their greatest oxidation state by ozone. At room temperature, ozone can still form carbon dioxide by reacting with carbon.

Decomposition of Ozone

The catalytic decomposition of ozone, a polluting gas commonly found or produced in human environments (such as aeroplane cabins, businesses with photocopiers, laser printers, and sterilizers), is essential for reducing pollution. When using solid catalysts, this is the most frequent breakdown type and offers several benefits, including better conversion at lower temperatures. Aside from these advantages, separating the product from the catalyst can be done without the requirement of any sort of separation procedure. Catalytic breakdown of ozone in the gas phase most typically involves noble metals as well as transition metals.

There are two ways to decompose ozone in the gas phase: 

Ozone can be decomposed in two ways

1. Thermal breakdown

2. Chemical degradation

The problem is that this type of breakdown is incredibly slow at temperatures below 250°C. Working at higher temperatures, on the other hand, can boost the breakdown rate, but at a significant energy cost. After ultraviolet radiation (UV) breaks down the ozone molecules into oxygen and radical peroxide, a photochemical breakdown ensues.

Conclusion

The ozone layer protects Earth’s surface from ultraviolet rays. Even low concentrations of gaseous or liquid ozone is toxic and can cause damage to living organisms. Because of its high oxidizing property, ozone has commercial as well as industrial uses. Industrial and consumer products releasing chemicals such as chlorofluorocarbons (CFCs) and halons into the environment have high potential for ozone depletion.

Ozone is a simple chemical compound consisting of only oxygen atoms. Ozone dissolves in water resulting in the formation of hydrogen peroxide.