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Stories About Chemistry


14. The Odour of Freshness,
or the Transition of Quantity into Quality Exemplified

Your breath comes easier after a thunderstorm. The air is clear and charged with freshness. This is not just a poetical image. Thunderclaps result in the formation of ozone gas in the atmosphere, and it is this gas that makes the air seem cleaner.

Ozone is essentially oxygen. The difference is that the oxygen molecule contains two atoms of the element, while the ozone molecule contains three. O2 and O3, one atom more or one atom less of oxygen, should that make a big difference? It does make a very big difference: Ozone and oxygen are entirely different substances.

Cartoon of woman in swim suit, seated under an umbrella marked O3

Without oxygen there is no life. On the other hand, ozone in large concentrations kills all living things. It is a most powerful oxidizing agent, second only to fluorine. On combining with organic substances ozone immediately destroys them. When attacked by ozone all the metals, except for gold and platinum, change rapidly into their oxides.

It is two-faced! A murderer of all living things, ozone also promotes life on the Earth in many ways. This paradox is easy to explain. Solar radiations are not uniform. They contain what are known as ultraviolet rays. If all these reached the Earth’s surface, life on Earth would be impossible because these rays carry an immense amount of energy and are fatal to living organisms.

Fortunately, only a very small fraction of the Sun’s ultraviolet rays reach the Earth’s surface. Most of them lose their force in the atmosphere at an altitude of 20-30 kilometres. At this level of the air blanket enveloping our planet, there is a great deal of ozone, and it absorbs the ultra­violet rays.

By the way, one of the present-day theories of the origin of life on Earth relates the appearance of the first organisms to the time of formation of the ozone layer in the atmosphere. But people need ozone on the Earth too, and in large quantities. They, and primarily chemists, need thousands and thousands of tons of ozone very badly.

The chemical industry would gladly make use of the astounding oxidizing power of ozone. Oil industry workers would also be pleased to bow down to ozone. The petroleum of many oil fields contains sulphur. Sour oils, as they are called, cause a great deal of trouble, for one thing, by rapidly corroding equipment, for instance, boiler stokers at power stations. With ozone such oils could easily be freed from sulphur, and the sulphur removed could be utilized to double or even treble the present production of sulphuric acid.

We drink chlorinated water. It is harmless, but its taste is inferior to that of spring water. Drinking water treated with ozone is absolutely free from pathogenic bacteria and has no unpleasant taste.

Ozone can renew old automobile tyres and bleach fabrics, cellulose, and yarn. There are many other things it can do. And that is why scientists and engineers are working on the design of high-capacity industrial ozonizers.

That is what ozone is! O3 is no less important than O2. Philosophy has long ago formulated the dialectical principle of the transition of quantity into quality. The example of oxygen and ozone is one of the most vivid manifestations of dialectics in chemistry.

There is another molecule known to scientists, consisting of four oxygen atoms, O4. However, this “quartet” is very unstable and hardly anything is known so far about its properties.

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